IE43845B1 - 4-thia-1-azabicyclo/4.2.0/oct-2-ene derivatives - Google Patents

Abstract

Compounds of the formula I in which R and E have the meaning stated in Claim 1 are antibiotics which are effective against Gram-positive and Gram-negative bacteria. They are prepared by N-acylation of compounds of the formula II in which R<2> is hydrogen or a carboxyl protective group with compounds of the formula RX' in which X' has the meaning stated in Claim 1, and elimination of any carboxyl protective group present. During the reaction, intermediate protection of the sensitive substituents present in the radical R is also possible. The carboxylic acids of the formula II in which E is bromomethyl are prepared by bromination of compounds of the formula IV-b in which the substituents have the meaning stated in Claim 25 with a compound which provides bromine free radicals in the presence of an initiator which provides free radicals, with subsequent elimination of the amino protective group, or if E in the formula IV-b is a lower alkanoyloxymethyl group, by reaction of a compound of the formula VIII in which the substituents have the meaning stated in Claim 29 with a salt of a lower alkanecarboxylic acid and subsequent elimination of the amino protective group.

Description

This invention relates to cephalosporin-like thia-azabicyclooctene derivatives which have antibacterial activity,to chemical intermediates for them and to processes for preparing such compounds.

Cephalosporins obtained by fermentation processes or ring expansion of penicillins all contain the 8-oxo5-thia-l-azabicyclo/4.2.q7oet-2-ene nucleus having the structure 5 Compounds with this ring system have been the object of intense research and numerous scientific articles and patents, and are the basis of a considerable number of commercial products available as antibacterial agents.

Analogous ring systems in which the sulfur atom is in another position in the six-membered ring cannot be obtained by the same methods as those which have been described’ for the above nucleus and a totally synthetic approach must be employed. One system which has been attempted with varied success is the 8-oxo-4-thia-lazabicyclo/4.2.07octane to which the trivial name isocephalosporin can be given, that is The synthesis of 7/3-phenylacetamido-7 Compounds have now been prepared having the 6,7ixh-8oxo-4-thia-l-azabicyclo/4.2.07oct-2-ene ring system; in particular, 7/?-acylamino-6« The thia-azabicyclooctene compounds of this invention are those of the structural formula: H H COOH where R is a carboxylic acyl group other than phenylacetyl, and E is hydrogen, methyl, bromomethyl, or lower alkanoyloxymethyl.

Preferably R is a group XCHWCO-, YCHgCO- or ZS(O) CHgCO-, where X is thienyl, cyclohexyl, cyclohexenyl, cyclohexadienyl, phenyl, or phenyl substituted by one or two substituents selected from lower alkyl, lower alkoxy, hydroxy, hydroxymethyl, halo, nitro, amino, aminomethyl, mercapto, lower alkylthio, trifluoromethyl, ureido, formamido, and carboxymethylamino; W is hydroxy, amino, formyloxy, carboxyl, or sulfonic acid -SOgH; Y is cyano, azido, phenoxy, or a 5- or 6- membered heterocyclic group containing from 1 to 4 hetero atoms selected from nitrogen, oxygen and sulfur, such heterocyclic group being unsubstituted or substituted with one or two substituents selected from lower alkyl, lower alkoxy, hydroxy, halo, nitro, afflino, aryl, and lower aralkyl; Z is phenyl, pyridyl, lower alkyl, trifluoromethyl, trifluoroethyl, or cyanomethyl, and n is 0, 1 or 2. The 5- or 6- membered heterocyclic groups include thienyl, furyl, thiazolyl, isothiazolyl, oxadiazolyl, thiadiazolyl, triazolyl, tetrazolyl, sydnonyl, pyridyl -343845 and pyrimidyl. Preferably E is hydrogen, methyl or acetoxymethyl.

By lower alkyl, is meant an alkyl group containing from 1 to 6 carbon atoms, and by lower alkoxy, lower aralkyl and lower alkanoyl are meant radicals whose alkyl portion is a lower alkyl group. The term halogen (or halo) means fluorine, chlorine or bromine.

More preferably X is thienyl, phenyl, £-hydroxyphenyl, j^0 4-hydroxy-3-fluorophenyl, or 4-earboxymethylaminophenyl; W is hydroxy or amino; Y is cyano, azido, phenoxy, thienyl, tetrazolyl, or sydnonyl; and Z is phenyl, pyridyl when n is 0, methyl, .trifluoromethyl, trifluoroethyl, or cyanomethyl .

L5 Thia-azabicyclooctene compounds which are also a part of this invention and which are useful as intermediates in the preparation of compounds of Formula X are those of the structural formula: H W Formula II !5 C0OR?where E is hydrogen, methyl, bromomethyl or lower alkanoyloxymethyl; each R3 is hydrogen or a monovalent removable amino-protecting group, or both R3 groups taken together form a divalent removable amino-protecting π group; and R is hydrogen or a removable carboxylprotecting group? Preferably E is hydrogen, methyl or acetoxymethyl.

The term removable carboxyl-protecting group 5 has acquired a definite meaning within the cephalosporin and other organic chemical arts. Many groups, particularly many ester-forming groups, are known which are used to protect the carboxyl groups during subsequent chemical reactions and are later removed by standard methods to give the free carboxylic acid group. Known carboxyl-protecting groups include 2,2,2-trichloroethyl, C^-Cg-tert-alkyl, such as t^-butyl, -4Cg-C?-tert-alkenyl, Cg-C^-tert-alkynyl, Cj-Cg-alkanoylmethyl, phthalimidomethyl, benzoylmethyl, naphthoylmethyl, furoylmethyl, thienoylmethyl, nltrobenzoylmethyl, halobenzoylmethyl, methylbenzoylmethyl, methane5 sulfonylbenzoylmethyl, phenylbenzoylmethyl, benzyloxymethyl, p-nitrophenyl, p-methoxyphenyl, benzyl, pnitrobenzyl, p-methoxybenzyl, benzhydryl, trityl, tritnethyleilyl, and triethylsilyl. The choice of which ester-forming group to use is well within the ability of one skilled in the art. Factors which are considered include what subsequent reaction conditions the group must withstand and what conditions for removing the protecting ester-forming group is desirable. Groups which are removed by treatment with trifluoroacetic acid, hydrogenation or zinc dust and acetic acid have been preferred in the art when a /3-lactam is fused to a six-membered ring. The choice of the protecting group is not critical since the essence of the invention lies in the new blcyclic nucleus and not in the ester-forming n SO substituents. Preferably, however, R is hydrogen, 2,2,2trichloroethyl, t-butyl, benzyl, benzhydryl, benzyloxymethyl, p-nitrophenyl, p-methoxyphenyl, p-nitrobenzyl, or p-methoxybenzyl.

The term removable amino-protecting group is well known in the art. A protected amino group is an amino group which has been masked by another group so as to protect it during subsequent chemical reactions, following which the masking group can be removed to regenerate the amino group. Many groups are known and used for this purpose within the penicillin, cephalosporin, and peptide synthetic arts. Examples of these are tbutoxycarbony1, trichloroethoxycarbonyl, benzyloxycarbonyl, ρ-methoxybenzylcarbonyl, isobornyloxycarbonyl, trityl and l-methoxycarbonyl-2-propenyl, which are monovalent protecting groups. Examples of divalent protecting groups are phthaloyl and that which, with the nitrogen of the amino group to be protected,forms a 4,5-diphenyl4-oxazolin-2-one ring. Treatment of a phthalimido group with hydrazine by published procedures cleaves the phthaloyl group to regenerate the amino group. Formation -543845 of the 4-oxazolin-2-one ring and regeneration of an amino group from it is taught in J. Org, Chem., 38, 3034 (1973). The choice of the protecting group depends on various factors including the subsequent chemical reaction conditions and the desired conditions for removal of the protecting group. However, this choice is within the ordinary ability of one skilled in the art. Again the choice of the amino-protecting group is not critical to this invention for the same reasons given above for the carboxyl-protecting group.

A compound of Formula XI is, however, preferably one where each R1 is hydrogen; or one where either one R1 is hydrogen and the other is t-butoxycarbonyl, trichloroethoxycarbonyl, benzyloxycarbonyl, methoxybenzylcarbonyl, isobornyloxycarbonyl, trityl, or 1methoxycarbonyl-2-propenyl; or RgN is phthalimido or 4,5-diphenyl-2-oxo-4-oxazolin-3-yl.

Examples of acyl groups R are those known in the semisynthetic penicillin and cephalosporin fields, including the following: -6α-hydroxyphenylacetyl a-formyloxyphenylace tyl α-aminophenylace tyl a-amino-4-hydroxyphenylacetyl a-amino-4-hydroxy-3-fluorophenylacetyl a-amino-4-carboxymethylaminophenylacetyl trifluoromethylmercaptoacetyl methylmercaptoacetvl methylsulfonylacetyl 2,2,2-trifluoroethylsulfinylacetyl cyanoaeetyl cyanomethylmercaptoacetyl cyanomethylsulfinylacetyl cyanomethylsulfonylacetyl a-carboxy-2-thienylacetyl a-carboxy-3-thienylacetyl α-carboxyphenylacetyl α-sulphophenylacetyl 3 -sydnony lacetyl 2- thienylacetyl 3- th ienylace tyl 1-tetrazolylacetyl.

The compounds of this invention contain a nucleus which is related to naturally occuring cephalosporins but which cannot he prepared by fermentation methods. Therefore the compounds are prepared by a totally synthetic route as outlined in DMB means a 2,4-dimethox.ybenzyl group, and Scheme 1. In Scheme I,/R is any acyl group as set out above or a derivative thereof in which any chemically sensitive group such as carboxy, hydroxy or amino is - 7 438 4 5 A xO tux X X H LU Σ Lu X u ω X cj o o CJ uT CJ rt, ro CJ Xllf XIII Ψ X / -z o α o U=Z~C 3 X ft -8protected with a standard removable protecting greup» Wnv of which have been described above, until the final step of the reaction sequence. Many protecting groups are set forth in the book Protective Groups in Organic Chemistry, ed. J.F.W. McOmie, Plenum Press, New York, 1973 and in text ι other review articles and/books. R is an amino protecting group which is removed after the 4-thia-l-azabieyclo[4.2.0] oct-2-ene nucleus is formed to give the 7-amino derivative.

This derivative can then be acylated by the same standard methods used within the cephalosporin art with the desired containing the group tir λ acyl group to give the compounds of this invention/. Rz is an ester-forming group used to protect the carboxyl group and is also removable at the end of the reaction sequence to give a free carboxyl group or a salt thereof.

The important intermediate which gives the new nucleus its 6.7-cls configuration is methyl cis-1(2,4-dimethoxybenzyl)-3-azido-4-oxoazetidine-2-carboxylate (3). This compound is prepared by a cyclo addition reaction between the imine/obtained from the condensation of 2,4-dimethoxybenzylamine with methyl glyoxyl ate and the or an mixed anhydride (2)/aeid halide of azidoacetic acid. The (3) azido group of this intermediate/is reduced by catalytic with hydrogenation or by chemical reduction such as kinc and acetic acid to give a 3-aminoazetidine derivative, which is then protected by a removable amino proto give the protected derivative (4) tecting group such as t-butoxycarbonyl/. A protected 3- aminoazetidine derivative can also be prepared directly by substitution of a glycine derivative in which the amino group has been protected. For example, 4,5-diphenyl-2-oxo4- oxazolin-3-ylacetyl chloride or phthalimidoacetyl chloride can - 9 . ' -jj ¢3848 be used, in the cyclization reaction in the same manner as azidoacetyl compound (2) to give the corresponding protected 3-amino-azetidine derivative. The derivative (4) is converted by oxidation with potassium persulphate to the secondary amine (5), and this is reduced with podium borohydride to the alcohol (6), which is converted in a series of steps to the mercaptomethyl derivative (7).

The intermediate (3) or the protected 3-aminoazetidine (4) can be converted by a series of reactions into the 2-tosyloxymethyl derivative as illustrated by compound (11) in Scheme II, where Ts is a tosyl (toluene2.- sulfonyl) group. Various reaction sequences can be used in.’.the preparation of compounds such as (11), Scheme II sets forth two alternate pathways which can be used to convert compound (3) to compound (11). It is apparent to persons skilled in the art that conversion of the azido group to the protected amino group is not limited to the two illustrated places along the reaction sequence but can also be effected at other places. Reduction of the azido moiety is advantageously effected on compound (3) in Scheme II or on the 3-azido-2-tosyloxymethyl derivative (12). The tosyl derivative (11) is then }5 converted stepwise to the mercaptomethyl derivative (7a), equivalent to (7) in‘Scheme I. Using sodium iodide the tosyl group is displaced by iodo, which is in turn displaced with a mercaptan R SH such as g-methoxybenzyl mercaptan or triphenylmethyl mercaptan. Cleavage of these derivatives by standard synthetic methods gives the mercaptomethyl compound (7a). The 2-methoxybenzyl group is cleaved by treatment with mercuric salts. The triphenylmethyl group Is cleaved by treatment with silver salts including silver nitrate and silver tetrafluoroborate and therefore is advantageous where other groups within the compound are sensitive to mercuric ion? -104 38 ι SCHEME -li438 45 Returning to Scheme I, / the mercaptomethyl compound 7 is reacted with a 0-bromo-a-keto ester to give the bicyclic compound 8. When a bromopyruvate ester is used, compound 8 where E Is hydrogen is obtained. When a 3bromo-2-. oxabutyrate ester is used, compound 8 where E is methyl is obtained. These compounds are dehydrated to give the 8-oxo-4-thia-l-azabicyclo[4.2.0]oct-2-ene compound 9. Standard dehydration reagents such as thionyl chloride, trifluoroacetic anhydride, and methanesulfonic anhydride can be. used.

Compounds of structure 9 where E is bromomethyl are prepared by radical bromination of the 3-methyl compounds using the procedures known in the cephalosporin used art. Bromination reagents include N-bromosuccinimide/in the presence of radical initiators such as benzoyl peroxide or azobisisobutyronitrile.

The bromomethyl derivatives can be reacted with various acetate salts to give compounds of structure 9 where E is acetoxymethyl. Examples of salts useful for this purpose include sodium, potassium, or silver acetate.

Compounds of structure 10, the antibacterial agents of this invention, are prepared from compounds of structure 9 by removal of the amino protecting group followed by acylation with the desired acyl group using standard acylation methods. Following the acylation any additional protecting groups are removed. During the acylation reaction any sensitive groups such as amino or hydroxy are protected as has been previously described.

Standard acylation methods include activation of the group carboxyl/by use of mixed anhydrides, activated esters, and acid halides or by use of coupling reagents such as 12. dicyclohexylcarbodiimide.

Some compounds of Formula I can alternatively be prepared by acylation with the desired acyl group earlier in the reaction sequence. For example, -- - from the azide (13) the 3-aminoa2etidinoee derivative can be prepared/and acylaand conversion effected ted/ at the same places as those disclosed in Scheme II. When this acylated monocyclic β-lactam is carried along the reaction sequence herein disclosed the desired final products are obtained. Examples of acyl groups for which this alternative method can be used include phenoxyacetyl, α-amlnophenylacetyl, a-amino-p-hydroxyphenylacetyl, 2-thienylacetyl.

More specifically, when 2,4-dimethoxybenzylamine [Chem, Ber.. 101, 3623 (1968)] is condensed with methyl 15 the glyoxylate [Synthesis, 544 (1972)],/imine 1 is obtained. Reaction of this imine with the mixed anhydride/ of trifluoroaeetic acid and azidoacetic acid [Tetrahedron Lett.. 2319 (1973)] gives methyl cis-l-(2,4-dimethoxybenzyl)-3azido-4-oxo»2-azetidinecarboxylate (3). This reaction can be run as a two-step process by first generating the mixed anhydride and then adding this to a solution of the imine. Alternatively, a one step procedure can be used in which the azidoacetic acid is added to a solution of the imine followed by the addition of the trifluoroacetic anhydride. In addition, other glyoxylate esters such as the ethyl or propyl/can be used in the same manner.

The 2,4-dimethoxybenzyl group is removed by oxidative methods. For example, treatment of the N-(2,4dimethoxybenzyl)- A-lactam with potassium persulfate effects the deblocking reaction to generate the free β-lactam.

This reaction is carried out In the presence of sodium . 13 _ monohydrogen phosphate. With some derivatives» pH control during the reaction within a range of 5-6 may be advantageous to the reaction yield. Under these conditions we have found that the benzyl group is not removed like the dimethoxybenzyl group. However, one skilled in the art could try other substituted benzyl moieties and determine if they are removable and therefore are also able to perform the same function as the dimethoxybenzyl group.

Reduction of the 2-alkoxycarbonyl group with suitable reducing agents such as sodium borohydride give s the 2-hydrwmethyl derivative. In particular, the methoxycarbonyl group is readily reduced with sodium borohydride to give the alcohol derivative.

The alcohol derivative can also be prepared by reduction of the 2-carboxylic acid by standard reduction methods known in the art. The acid is prepared from the ester derivative by base hydrolysis. For example, the methyl ester hydrolyzes to the carboxylic acid by treatment with sodium carbonate, potassium carbonate or similar base. The carboxylic acid can be converted to its acid chloride and reduced with sodium borohydride to give the desired alcohol. The l-(2,4-dimethoxybenzyl)-2-carboxylic acid derivative can be reduced to the 2-'hydi®xsnnethyT . derivative which can be converted to the corresponding tosylate. The dimethoxybenzyl group can be removed at this point to give the β-lactam methyl tosylate precursor which can be carried further as has been described.

The alcohol is treated with toluene _£sulf«iyl «feliorida, heazaaesulfEayl chloride, mesyl chloride or similar reagent's whidh convert - U . 4384» the hydroxy group into a group which is readily displaced by iodide ion by nucleophilic displacement. Standard nucleophilic displacement of the sulfonate moiety with iodide followed by another nucleophilic displacement with sulfur derivatives gives the mercaptomethyl group or a group which can be converted to the desired mercaptomethyl group. Triphenylmethylmercapto and p-methoxybenzylmercapto are typical groups which are readily cleaved to the free mercapto group as set out above.

The new cephalosporin-like nucleus is generated by a cyclization reaction of the mercaptomethyl compound and a bromopyruvate derivative. The product formed contains a hydroxy group alpha to the carboxyl group. Dehydration of this hydroxy group places the double bond in the nucleus at the 2,3-position analogous to the cephalosporin series. Dehydration is best carried out with thionyl chloride and pyridine or trifluoroacetic anhydride.

Intermediates useful for the preparation of the compounds of Formulae I and II are those of the structural formula: Formula III where A is azido Ng, amino, acylamino, or protected amino; B is COOH, lower alkoxycarbony 1, iodomethyl, p-methoxybenzylthiomethyl, trlphenylmethylthiomethyl, mercaptomethyl; or CHgOM, where M is hydrogen, lower alkanesulfonyl or phenylsulfonyl, such phenyl being unsubstituted, or substituted with methyl or halogen; and G is hydrogen or 2,4-dimethoxybenzyl. These intermediates are described and claimed in Patent Application 43846.

The preparation of such intermediates is described below. Starting materials for these intermediates are commercially available, or are prepared by known methods or described below. -15^3845 The compounds of Formula I can be in the form Of the free carboxylic acid or its salts, particularly their pharmaceutically-acceptable salts. These include the salts of the carboxylic acid at position 4 or within the acyl side chain and the acid addition salts of any basic substituent present in the compound. Carboxylic acid salts include those where the cation is an alkali metal such as sodium or potassium, an alkaline earth metal such as calcium, or an optionally substituted ammonium cation such as ammonium and cyclohexylammonium. -1643845 be The acid addition salts can /prepared from those acids known and used in pharmaceutical preparations including both inorganic and organic acids. The salts are prepared by the standard methods well known in the art.

The compounds of this invention oi- Formulae I and II exist in the cis configuration at positions 6 and 7. The compounds also exist as optical isomers. Included within the scope of this invention are the separate optical isomers as well as any mixtures thereof.

The compounds of Formula I of this invention have antibacterial activity against both Gram-positive and Gram-negative bacteria. For example, 7-phenoxyacetamido-8-oxo-4-thia-l-azabicyclo[4.2.0]oct-2-ene-2carboxylic acid has antibacterial activity against Staphylococcus aureus and Shigella paradysenterlae. The compound 7-(a-aminophenylacetamido)-8-oxo-4-thia-lazabicyclo[4.2.0]oct-2-ene-4-carboxylic acid has additional activity against Escherichia coli. Klebsiella pneumoniae, Serratla marcescens. Salmonella paratyphi. Shigella paradysenterlae. and Enterobacter species. The compounds are useful for the treatment and prevention of bacterial infections as well as for sterilization of glassware and other equipment.

The compounds of Formula II are useful as chemical intermediates in the preparation of novel cephalosporin-like compounds of Formula I as has been . each R described herein. Compounds of Formula II where / is hydrogen can be acylated as described above with any of the acyl groups known in the cephalosporin or penicillin arts to-give compounds which, after removal of any ester protecting group, have antibacterial activity. Compounds °f Formula II where R^ is an amino protecting group . 17 _ 4384s are useful for preparing the compounds where R1 is hydrogen.

The following Examples illustrate the invention 5 and are accompanied by Preparations of intermediates.

All temperatures are in °C. -1843845 PREPARATION 1 Methyl N- (2,4-dirnethoxybenzyl·) Iminoacetate To a mixture containing 16.82 g (0.101 mole) of 2.4- dimethoxybenzylamine and anhydrous magnesium sulfate in 150 ml of methylene chloride at 25° is added a solution of 10.05 g (0.114 mole) of methyl glyoxylate in ml of methylene chloride. The reaction mixture is stirred at room temperature overnight (15 hours) and then is filtered and the solvents are removed in vacuo to afford the imine as a dark orange gum.

PREPARATION 2 4.5- Dlphenyl-2-oxo-4-oxazolin-3-ylacetlc acid chloride A mixture of 4,5-diphenyl-2-oxo-4-oxazolin-3ylacetic acid (2.1 g, 7.1 mmol)[J. Org. Chem,, 38, 3034 (1973)], thionyl chloride (5 ml) and methylene chloride (20 ml) is refluxed for 2.5 hours. After cooling to room temperature the solvent is removed in vacuo and resulting oil crystallizes on standing. The product is triturated with ether-hexane to give the title compound; 2.0 g mp 104-112°.

PREPARATION 3 Bromopyruvate Esters To a solution of 3.3 g (37.5 mmole) of pyruvic 2,2,2acid and 7.9 g (37.5 mmole) of/trichloroethyl chloroformate in 20 ml of dry tetrahydrofuran at 0° is added dropwise 0.6 ml of pyridine. After stirring for 2 hrs. at room temperature, the mixture is concentrated in vacuo, diluted with water and extracted with ethyl acetate. The extract is washed with 57. HC1, dried over MgSO^, evaporated and distilled in vacuo to give 4.0 g (50%) triohloroethyl pyruvate, bp 75-82° (17 nm). 38 46 2,2,2-Trichloroethyl pyruvate (3,7 g, 17 mmole) is heated to 65° and 1.1 ml (17 mmole) of bromine is added dropwise over 1 hr. A stream of carbon dioxide is passed through the reaction mixture during the addition to remove the HBr formed in the reaction. The mixture is cooled to room temperature, diluted with water and extracted with ethyl acetate. The extract is dried over MgSO^, evaporated 2,2,2and distilled in vacuo to give 1.8 g of/trichloroethyl bromopyruvate, bp 74-77° (0.01 mm).

, Bromopyruvic acid is treated with diphenyldiazomethane by standard methods to give benzhydryl bromopyruvate.

The t-butyl ester is also prepared by standard methods by reacting 0-t-butyl-N,N'-dIisopropylpseudourea [Ann. Chem., 597, 235 (1955)]and bromopyruvic acid.

PREPARATION 4 3-Bromo-2-; oxobptyrate esters At room temperature under argon 1.85 g (9.6 mmol) of diphenyldiazomethane in 15 ml of dry benzene is added dropwise to a solution of 1.30 g (7.35 mmol) of 3-bromo2-’· oxobutyric acid in 15 ml of dry benzene with vigorous stirring. Addition of the diazo compound is continued until a faint red color persisted (0.5 hr). The solvent is removed in vacuo and the yellow oil is dissolved in ether, filtered and concentrated to give 3.12 g crude benzhydryl ester. Chromatography on silica gel,eluting with benzene affords 2.43 g (95%) pure benzhydryl 3-bromo-2oxobutyrate as a yellow oil.

A solution of 1.6 g (8.85 mmol) of 3-bromo-2obutyric acid and 7 g (4 equivalents) of O-tpbutylΝ,Ν'-diisopropylpseudourea in 14 ml methylene chloride . 4384B is stirred overnight at room temperature. After filtration, the solution is washed with NaHCO^ and brine, dried and evaporated to an oil which is chromatographed on silica gel with benzene as eluant to give 1 g (45%) of jt-butvl 3-bromo-2- oxobutyrate. f / PREPARATIOM 5. .

Methyl cis-l-(2,4-dimathaxybenzyl)-3-azido-4-oxoazetidine2-carboxyiate ' ' Method A: To a solution of 15.1 g (0.149 mole) of azidoacetic acid in 130 ml of anhydrous methylene chloride at 0° (ice bath) is added dropwise 21.0 ml (0.15 mole) of trifluoroacetic anhydride. This mixture is stirred at 0° for 15 min and then 20.8 ml (0.15 mole) df triethylamine is added dropwise. Stirring is continued for an additional 45 min and then the entire reaction mixture is transferred under argon into an addition funnel which is cooled externally by dry ice. The addition funnel is attached to a flask containing the imine from Preparation 1,200 ml of anhydrous methylene chloride, and 20.8 ml (0.15 mole) of triethylamine. The solution of the mixed anhydride is added dropwise from the addition funnel to the solution of imine at .0°. Stirring is continued at 0° for 1 hr and then the dark reaction mixture is transferred to a separatory funnel and washed with E^O, aqueous NaHGOg and brine and then dried over anhydrous magnesium sulfate. The solvents are removed in vacuo and the residue is chromatographed on 300 g of silica gel (70-230' mesh), affording an off-white solid which is further purified by trituration with ether to give 14.45 g (45%) of the title product as a white solid; tic: benzene: ethyl acetate (1:1), silica gel GF., Rf « 0.64. Recrystallization from ethyl acetate-hexane affords an analytical sample, mp 82-84°. - 22 43845 Method Β: 2,4A solution of 1.6 g (9.55 mmol)/dimethoxybenzylamine In 5 ml of CH2CI2 Is rapidly added at 0° to a solution of 1.06 g (10 mmol) freshly distilled methyl glyoxylate in 15 ml CI^C^· A slight exotherm occurred and water droplets appeared. Magnesium sulfate (5 g) is added and the mixture stirred at 0° for 2 hr. Fresh magnesium sulfate (1.0 g) is added, the magnesium sulfate removed by filtration under argon and washed with a minimum of 0¾¾.

To a solution of 3.8 g (36 mmol) of azidoacetic over acid (pumped in high vacuum/3 hr) in 125 ml of CH2CI2 is added 10.6 ml (76 mmol) of triethylamine with cooling. Magnesium sulfate (3 gm) is added, the mixture stirred 10 min at room temperature, filtered under argon and washed with a 25 ml CH2CI2· The azidoacetic acid solution is added at 0° to the imine, sufficient methylene chloride is added to bring the total volume to 200 ml, the solution cooled to 0° under argon and 5.3 ml (38mmol) trifluoroacetic anhydride added slowly over 1/2 hr with vigorous stirring and cooling. The mixture is stirred for 1 hr at 0°, allowed to warm to room temperature, transferred to a separatory funnel, washed with water, 5% NaHCOg, 27. phosphoric acid and 57. NaHCOg, dried over magnesium sulfate-charcoal; filtered and the filtrate is retreated twice with charcoal and evaporated to dryness. The residue is dissolved in a minimum of ether and stored at -20° to allow crystallization. The crystalline mass was isolated and washed with cold ether to give 1.9 gm (647.) product, mp 79 -80.5°.

PREPARATION 6.

Methyl cls-1-(2,4-dimethoxybenzyl)-3-amino-4-oxoazetldine2- carboxyl'ate A mixture containing 10.0 g (0.0312 mole) of methyl cis-1- (2,4-dimethoxybenzyl)-3-azido-4-oxoazetidine-2carboxylate, 1.0 g of 10% palladium on carbon, and 200 ml of ethanol Is hydrogenated for 2 hrs at 40-45° and 60 psi of hydrogen. The reaction mixture is allowed to cool to a ° and is filtered through/filter-aid. After removing the solvents in vacuo a clear, yellow gum of the title product is obtained.

REPARATION 7.

Methyl cis-3-fr43uioxycarbonylatnino -1-(2,4-dimethoxybenzyl) -4oxoazetidine-2-'carboxylate A solution of 5.5 g (18.8 mmole) of methyl cis3- amino-l-(2,4-dimethoxybenzyl)-4-oxoazetidine-2-carboxylate in 100 ml of dry toluene is cooled to -78°; 2.5 ml (18.8 mmole) of triethylamine is added followed by rapid addition of 35 ml (42 mmole) of a 12% solution of phosgene ln for and benzene. The mixture is stirred /15 min at -78°/ 3 hr at -45°(acetonitrile-dry ice), then warmed to room temperature and concentrated to half volume in vacuum. To the resulting solution is added 50 ml of t-butanol and the mixture is stirred-at room temperature overnight. The solvents are removed in vacuo the residue is diluted with ethyl acetate and filtered. The filtrate is transferred to a separatory funnel and washed with 5% NaHCOg, 5% HC1 and brine; dried over magnesium sulfate and evaporated to dryness; Recrystallization of the crude, crystalline product affords 3.8 g (52%)of the title compound.

Recrystallization from ether gives an analytical sample. . 24 .

PREPARATION 8.

Methyl cis-1-(2,4-dimethoxybenzyl)-3-phthalimido-4-oxo'azetldine“2-carboxvlate 2,4-Dimethoxybenzylamine (5.01 g, 0.03 mol) and methyl glyoxylate (3.17 g, 0.036 mol) are condensed as in Preparation 1 but at 0-5° for 2 hours. The resulting imine is dissolved in methylene chloride (800 ml) and cooled in an ice bath. Triethylamine (5.4 ml) is added followed by the dropwise addition of a solution of phthalimido acetyl ' chloride (7.54 g, 0.0338 mol) [J. Amer. Chem. Soc. 71, 1856 (1949)] in methylene chloride mixture for (80 ml). After the reaction/is stirred/2 hours, the solution is concentrated and then is washed with water, dilute HC1, and dilute NaHCOg. The dried organic phase is evaporated to give the title product which is triturated with ether; 6.4 g (50%). / <»3845 PREPARATION 9.

Methyl cis-1-(2,4-dimethoxybenzyl)-3-(4,5-diphenyl-2-oxo-4oxazolin-3-yl)-4-oxoazetidine-2-carboxylate The imine from Preparation 1 (1.43 g) is dissolved in dry methylene chloride (13 ml) and triethylamine (1 ml) and cooled in an ice bath. The acid chloride from Preparation 2 (2.0 g, 6.4 nmol) in methylene chloride (10 ml) is added over a 10-minute period. After one hour, the mixture is washed with water and 5% NaHCOj, the dried solution is evaporated to a red oil which is chromatographed on 60 g of silica gel with 5% ethyl acetate in chloroform as eluant to give the title product, 2.37 g.

PREPARATION, )0.

Methyl cis-1-(2,4- dimethoxybenzyl)-3-phenoxyacetamido-415 oxo-_. _azet idine-Z-carboxyl ate ' ' The crude amine prepared in Preparation/ from 10 g of the azido precursor is taken up in 100 ml of anhydrous methylene dichloride and is cooled to 0° in an ice bath.

To this solution is added 4.32 ml (0.0312 mol) of triethyl20 amines, followed by the slow addition of a solution of .32 g (0.0312 mol) of phenoxyacetyl chloride In 40 ml of methylene dichloride. The mixture is stirred at 0° for 1 hr, then poured into a separatory funnel and extracted successively with water, aqueous HC1, aqueous and NaHCOg/ brine and is dried over anhydrous magnesium suiate. After filtration the solvent is removed in vacuo to give a yellow solid. This material is partially dissolved in ether, cooled to -25°, and filtered to afford 11.2 g (84%) of the title product as a white solid (0 which is one spot on tic: benzene-ethyl acetate (1:1), silica gel, Rf 0.38. An analytical sample, mp 115.5-11^, - 26 . 4384ε is obtained by recrystallization from ethyl acetate-hexane. PREPARATION Π .

When p-methoxybenzyl alcohol, isobomeol, benzyl alcohol, or 2,2,2-trichloroethanol is substituted for 7, t-butanol in Preparation/., methyl 3-(p-methoxybenzyloxycarbonylamino)-1-(2,4-dimethoxybenzyl)-4-oxoazetidine-2carboxvlate, methyl 3-(isobomy loxycarbony lamino)-1-(2,4dimethoxybenzyl)-4-oxoazetidine-2-carboxylate, methyl 3-(benzyloxycarbonylamino)-1-(2,4-dimethoxybenzyl)-4oxoazetidine-2-carboxylate, or methyl 3-(2,2,2-trichloroethoxycarbonylamino)-1-(2,4-dimethoxybenzyl)-4-oxoazetidine-2-carboxylate is obtained.

Methyl 3- (isobomy loxycarbony lamino) -1- (2,4dimethoxybenzyl)-4-oxoazetidine-2-carboxylate can also be prepared by treating the 3-amino compound with isobornyloxycarbonyl chloride in the presence of base according to standard procedures; Chem. Pharm. Bull,, 20, 1017 (1972).

PREPARATION 12.

Methyl cls-3-t-tutoxycarbonylamino-4-oxoazetidine-2carboxylate cisA solution of 10.5 g (26.7 mmole) of methyl73-tbutoxycarbonylamino-1-(2,4-dimethoxybenzyl)-4-oxoazetidine2-carboxylate in 500 ml of acetonitrile is degassed with argon and warmed to 80°. A degassed solution of 15 g (55.5 mmole) of potassium persulfate and 7.5 g (28 mmole) of sodium monohydrogen phosphate in 150 ml of water is mixture added in five portions over 1 hr. The reaction/is stirred at 80-85° under argon for 2-3 hrs until all starting material is consumed (tic). The reaction mixture is and cooled, concentrated in vacu< / shaken with ethyl acetatewater, The organic phase is washed with dilute HC1, - 27 43845 NaHCOg solution and brine; dried over magnesium sulfate and evaporated to dryness. The residue is chromatographed over silica gel with 1:1 benzene-ethyl acetate to afford is pure product which/crystallized from ethyl acetate-hexane to yield 2.0 g (31%) of the title compound. A less pure fraction from the column, is crystallized from ethyl acetate-hexane to give an additional 0.5 g of product, overall yield, 38%.

PREBA8ATI0N 13.

When the products of Preparations 5, 8, 9, 10 and 11 are treated with potassium persulfate and sodium monohydrogen phosphate according to the procedure of Preparation 12 tin following products are obtained: methyl cis-3-azido-4-oxoazetidine-2-carboxylate; 72% yield mp 77-78° methyl cis-3-phthalimido-4-oxoazetidine-2carboxylate; 40%, yield methyl cis-3- (4.5-diphenvl-2-oxo-4-oxazolin-3yl)-4-oxoazet£dine-2-carboxylate, 32% yield methyl cis-3-phenoxyacatamldo-4-oxoazetldine-2carboxylate; 69% yield, mp 140-41° methyl cis-3-isobomy loxy carbonyl ami no-4-oxoazetidine-2-carboxylate methyl cis-3-(p-methoxybenzyloxycarbonylamino)-4oxoazetidine-2-carboxylate methyl cis-3-(benzyloxycarbonylamino)-4oxoazetidine-2-carboxylate methyl cis-3-(2,2,2-trichloroethoxycarbonylamino)4-oxoazetidine-2-carboxylate 3 8 4 8 PREPARATION 14.

Methyl cls-3-amino-4-oxoazetidine-2-carboxvlate A solution of methyl cls-3-azldo-4-oxoazetidlne5 2-earboxylate (8.5 g, 50 mmol) and an equivalent of toluene-p-tulfonic acid in 200 ml of ethanol is hydrogenated — « for 3 hours over 1 g of 107« Pd on carbon at 40 psi. The give the solution is filtered and the filtrate is evaporated to/title product or the tosylate salt which can be converted to IQ the free base by standard methods.

PREPARATION 15.

A solution of anhydrous l^COg (249 mg, 1.8 mmol) in tetrahydrofuran (8 ml) and water (12 ml) is degassed with argon and then methyl cls-3-phenoxyacetamldo-l15 (2,4-dimethoxybenzyl)-4-oxoazetidine-2-carboxylate mixture (150 mg, 0.35 mmol) is added. The reaction/is stirred for 1.5 hours at room temperature, the organic solvent is evaporated and the aqueous layer is acidified and extracted with methylene chloride. The dried extracts are evaporated 2Q to give a solid which is recrystallized from ethyl acetate-hexane to give pure cis-3-phenoxyacetamido-l(2,4-dimethoxybenzyl)-4-oxoazetidine-2-carboxylic acid, mp 169-170° (dec).

Methyl cis-3-phenoxvacetamldo-4-oxoazatldine-225 carboxylate is treated with K^COg in methanol-water as above to give cis-3-phenoxyacetamido-4-oxoazetidine-2carboxylic acid, mp 150-51° from ethyl acetate.

TO 29^3845 PREPARATION 16. ds-3-^»Butoxycarbonylamino-2-hydroxymethyI-4-oxoazetidine —A solution of 2.0 g (8.2 mmole) of methyr73-t- butoxycarbonylamino-4-oxoazetidine-2-carboxylate in 20 ml of tetrahydrofuran is cooled in ice and a solution of 0.75 g (20 mmole) of sodium borohydride in 10 ml of water for is added. The mixture is stirred/20 min at 0° and then 1.5 hr at room temperature. Acetic acid is added dropwise to decompose the excess borohydride and the mixture is concentrated in vacuo. The residue is diluted with brine and extracted with ethyl acetate. The organic phase is washed with brine and 57. NaHCOg; dried over magnesium sulfate and evaporated to dryness to give 0.9 g (507.) of the title product as white crystals, mp 128-131°.

PREPARATION 17.

When the 3-azido, 3-oxazolinyl, 3-phenoxyacetamido, 3-isobornyloxycarbonylamino, 3-(p-methoxybenzyloxycarbonylamino, and 3-benzyloxycarbonylamino 13 compounds from Preparation/are reduced with sodium boro16 hydride by the procedure of Preparation / the following products are obtained: cis-3-azido-2-hydroxvmethvl-4-oxoazetidine; 56%. yield cis-2-hydroxvmethvl-3-(4,5-diphenyl-2-oxo-4oxazolin-3-yl)-4-oxoazetidine; ca. 1007. yield cis-2-hydroxymethyl-3-phenoxyacetamido-4-oxoazetidine; 68% yield, mp 153-4° (from ethyl acetate) cis-2-hydroxymethyl-3- isobornyloxycarbony lami no-4oxoazetidine 8 Ί δ cis-2-hydroxymethyl-3-(£-me thoxybenzyloxycarbonylamino)-4-oxoazetidine cjLs-3-benzy loxycarbony lamino-2-hydroxymeth.y 1-4oxoazetidine PREPARATION 18. cis-3-t-Butoxycarbonylamino-4-oxo-2-azetldinylmethyl tosylate ——— To a solution of 0.9 g (4.3 mmole) of 98% £toluenesulfonyl chloride in 10 ml of dry pyridine at 0° cisis added 0.9 g (4.15 mmole) of 73-t-butoxycarbonylamino2-hydroxymethyl-4-oxoazetldine. The mixture is stirred for 2 hr at 0° and then stored at 5° overnight. After addition of 0.5 ml of 85% lactic acid, the mixture is stirred for 1 hr, poured into ethyl acetate and washed with dilute HC1, 5% NaHCOg, and brine. The extract is dried over magnesium sulfate and evaporated to dryness to give 1.1 g (70%) of crystalline title product. Recrystallization from hexane-ethyl acetate gives an analytical sample, mp 160-162° (dec).

PREPARATION 19.

Treatment of the products obtained in Preparation 17 with tolnene-p-sulfonyl chloride according to the procedure “ 18 of Preparation/ gives the corresponding tosylates: cis-3-azldo-4-oxo-2-azetldinvlmethyl tosylate; 80% yield,mp 87-89° cis-3-(4,5-diphenyl-2-oxo-4-oxazolin-3-yl)-4“ oxo-2-azetidinylmethyl tosylate cis-3-phenoxyacetamido-4-oxo-2-azetidinylmethyl tosylate; 71% yield, mp 136° (dec) cis-3-isobornyloxycarbonylamino-4-oxo-2azetidinylmethyl tosylate 13 8 4 β cis-3- (p-methoxybenzyloxycarbonylami.no) -4-oxo2-azetidinylmethyl tosylate cis-3- carbonylamino-4-oxo-2-azetidinyl methyl tosylate When c is-2-hydroxyme thyl3-(4,5-diphenyl-2-oxo-4-oxazolin-3-yl)-4-axoazetidine is 18 reacted according to Preparation/ except that mesyl chloride is substituted for toluene-^sulfonyl chloride, cis-3(4,5-diphenyl-2-oxo-4-oxazolin-3-yl)-4-oxo-?.-azetidinylmethyl mesylate is obtained; 73% yield, mp 185-8° from ethyl acetate-hexane. 3 8 4 8 PREPARATION . 20. cis-3-Amino-4-oxo-2-azetidinyImethyl tosylate A solution of cls-3-azido-4-oxo-2-azetldinylmethyl tosylate (5.0 g) in 50% aqueous acetic acid (50 ml) is cooled and then treated with zinc dust (2.0 g). The mixture reaction/is stirred for 30 minutes, filtered, aid the solid washed with (50 ml). The filtrate is saturated with H2S over 1/2 hour, the zinc sulfide is removed by filtration and the filtrate evaporated to near dryness.

The residue is dissolved in ethyl, acetate-water and adjusted to pH 10. Phases are separated and the aqueous layer is extracted with ethyl acetate. The dried organic phases are evaporated to give the amino compound; 3.0 g (66%).

PREPARATION 21.

A mixture of the 3-amino tosylate compound from 20 Preparation/ (0.14 g), N-t-butoxycarbonylphenylglycine (0.16 g) and dicyclohexylcarbodiimide (0.12 g) in methylene for chloride (5 ml) is stirred/one hour at 0 . The solid is removed by filtration and the filtrate is evaporated to dryness. The residue is chromatographed on silica gel with 80:20 ethyl acetate-benzene as eluant to give c is-3-(a-t-butoxycarbonylamino phenylacetamido)-4-oxo-2azetidinylmethyl tosylate; 0.19 g (70%). 2-Thienylacetic acid, the 3-amino derivative from Preparation/ and dicyclohexylcarbodiimide (3.7 mmol of each)are reacted in methylene chloride as above. The mixture is diluted with ethyl acetate (150 ml) and filtered; the filtrate is washed with 5% NaHCO^, dilute HC1, and brine, dried, evaporated and crystallized from acetoneether to give cls-3-(2-thlenylacetamido)-4-oxo-2-azetidlnvlrnethyl tosylate; 0.9 g (69%) mp 121-124 °.

The 3-amino derivative is acylated with 0-formylmandelic acid chloride in the presence of triethylamine to . 33 . 4384E give cis-3-0-formylHiandetotdo-4-oxo-2-axet1dinylmethyl tosylate, 98% mp 111-113 (dec).

PREPARATION 22. cj^.-3-Phenoxyacetamido-4-oxo-2-azetidind<1®ethyl iodide A mixture containing 13.68 g (33.9 mmol) of cis3-phenoxyacetamido-4-oxo-2-azetidiney3aafchyl tosylate, 39.8 g (0.265 mol) of sodium iodide and 550 ml of acetone is heated at reflux for a period of 6 hr and then is allowed to cool to ambient temperature. The acetone is removed in vacuo 3X1,1 the residue is suspended in ethyl acetate and extracted with water, sodium thiosulfate and brine. The dried ethyl acetate solution was evaporated in vacuo to give a yellow semicrystalline residue. Recrystallization from ethyl acetate resulted in 10.3 g (84%) of crystalline product; mp 150° (dec).

FREKARATION--23.

When the appropriate tosylates- or mesylates which are disclosed in Preparations 18, 19 and 23 are treated with sodium iodide by the procedure disclosed in Preparation 22 the following products are obtained: cis-3-t-butoxycarbonylamino-4-oxo-2-azetidiny1methyl iodide cis-3-azido-4-oxo-2-azetidinylmethyl iodide cis-3-(4,5-diphenyl-2-oxo-4-oxazolin-3-y1)-4oxo-2-azetidinylmethyl iodide cis-3-(α-t-butoxycarbonylaminophenylacetamido)-4oxo-2-azetidinylmethyl iodide, 78%, yield cis-3/thienylacetamido)-4-oxo-2-azetidinylmethyl iodide, 98% yield cis-3-Q.-formylmandelamido-4-oxo-2-azetidinylmethyl iodide cls-3-isobomyloxycarbonylamino-4-oxo-2azetidinylmethyl Iodide cls-3- (p-methoxybenzyloxyca3fbonylami.no) -4-oxo-2azetidinylmethyl iodide cis-3-benzyloxycarbonylamino-4-oxo-2-azetidinylmethyl iodide PREPARATION 24. 3-t-Butoxyoarbonylamino-4-oxo-2- (£_-methoxybenzylthiomethyl) agetidine To a solution of 1.1 g (2.97 mmole) of 3-1 butoxycarbonylamino-4-oxo-2-azetidinylmethyl tosylate in 15 ml of dry dimethylformamide under argon was added 4.0 g (26 nmole) of sodium iodide. The mixture was heated to 65° for 4 hours, then stirred at room temperature overnight. The resulting suspension was diluted with 50 ml of ethyl acetate, filtered, concentrated in vacuo,. flushed with argon and 3.0 ml Of' g-methoxybenzyl mercaptan and 2.0 ml of triethylamine were added. The mixture was stirred at room temperature for 18 hours and then poured into ice water-ethyl acetate. The organic phase was separated and washed with water, 5% NaHCOg and brine; dried over magnesium sulfate and evaporated to dryness. The residue was chromatographed over silica gel with 1:1 benzene-ethyl acetate to afford, after evaporation and crystallization from ethyl acetate-hexane, 335 mg (32%) of pure product, mp 120-123°. 8 45 PREPARATIOM 25.

When an appropriate iodide derivative is reacted with p-methoxybenzyl mercaptan (2 equivalents) in the presence of triethylamine (2 equivalents) according to the 24 procedure set forth in Preparation/^ the following compounds are obtained cis-3-phenoxyacetamido-4-oxo-2-(p-methoxybenzylthiomethyl)azetidine; mp 139-41° cis-3-Οτ f ormylmandelamido-4-oxo-2- (p-methoxybenzylthiomathyl)azetidine cis-3-(a-t^butoxycarbonylaminophenylacetamido)-4oxo-2-(^-methoxybenzy1thiomethyl)azet idine cis-3-i sobornyl oxycarbonylamlno-4-oxo-2- (jj-methoxybenzyIthiomethyl)azetidine cis-3-(p-methoxybenzyloxycarbonylamino)-4-oxo-2(p-methoxybenzylthiomethyl)azetidine cis-3-benzyloxycarbonylamino-4-oxo-2-(p-methoxybettzylthlomethyl)azetidine - 36 PREPARATION 26. cis-3-(2-Thienvlacetamido)-4-oxo-2-(triphenvlmethvlthiomethyl)azetidine To a solution of 0.8 g (2.3 mmole) of cis-3(2-thienylacetamido)-4-oxo-2-azetidinemethyl iodide and 0.9 g (9 mmole) of triethylamine in 10 ml of dry dimethylformamide is added 1.27 g (4.6 mmole) of triphenylmethanethiol. The mixture is stirred under argon overnight, diluted with 100 ml of ethyl acetate and washed with dilute HC1 and water. After drying with magnesium sulfate, the extract is evaporated to dryness and the residue triturated with ether. The crystalline product is filtered and dried to give the title compound.

PREPARATION 27.

When the methyl iodide derivatives of Preparations 22 and 23 are reacted with triphen/ylmethanethiol according to the procedure of Preparation/ the following compounds are obtained. cis-3-phenoxyacetamido-4-oxo-2-(triphenylmethylthiomethyl)azetidine cls-3-t-butoxvcarbonvlamino-4-oxo-2-(triphenylmethyl thiomethyl)azetidine cis-3-(4,5-diphenyl-2-oxo-4-oxazolin-3-yl)-4oxo-2-(triphenylmethylthiomethyl)azetidine cis-3-(a-tfbutoxycarbonylaminophenylacetamido)-4oxo-2-(triphenylmethylthiomethyl)azetidine c^se3_0.formylmandelamido-4-oxo-2-(triphenylmethylthiomethyl)azetidine cis-3-isobomvloxvcarbonvlamino-4-oxo-2- (triphenylmethylthiomethyl)azetidine - 37 43845 cis-3-(p-methoxybenzyloxycarbonylamino)-4-oxo-2(triphenylmethylthiomethyl)azetidine cis-3-benzyloxvcarbonvlamino-4-oxo-2-(triphenylmethy1thiomethyl)azetidine PREPARATION 25. c i s -3-t-b.utoxvcarbonvlamino-4-oxo-2-mercaptomethylazetidlne To a solution of 335 mg (0.95 mmole) of 3-t> butoxycarbonylamino-4-oxo-2-(p-methoxybenzylthiomethyl)azetidine in 5 ml of methanol and 20 ml of methylene chloride Is added 1.7 g (5.3 mmole) of mercuric acetate, for The mixture is stirred/24 hours under argon, diluted with excess ether and the precipitated mercury adduct filtered and washed well with ether. The. mercury complex is suspended in water, layered with ethyl acetate and hydrogen sulfide gas is passed through the mixture for 1 hour. The mercuric sulfide is removed by filtration, the ethyl acetate layer is separated and washed with brine, dried over magnesium sulfate and evaporated to dryness. Trituration of the residue with 1:1 ethyl acetate-hexane gives 122 mg (55%) of the crystalline title product. _ 38 . 438 PREPARATION 29. cis-3-(2»Thienylacetamido)-4-oxo-2-mercaptomethylazetidine To a solution of 0.1 g (0.2 mmole) of cls-3(2-thienylacetamido)-4-oxo-2-(trlphenylmethylthiomethyl)azetidine in 3 ml of methanol is added a solution containing 34 mg (0.2 mmole) of silver nitrate and 16 mg (0.2 nmole) of pyridine. A precipitate of the silver mercaptide is formed immediately. Hydrogen sulfide gas is passed through the mixture for 5 minutes, the silver sulfide removed by filtration and the filtrate diluted with ethyl acetate and washed with dilute HC1 and brine.

The extract is dried and evaporated to dryness; trituration with ether gives the title compound as white crystals.

PREPARATION 30.

When the p-methoxybenzylthiomethyl derivatives 25 prepared in Preparation/ are deblocked according to the 28 procedure of Preparation//the following compounds are obtained. cis-3-phenoxyacetamido-4-oxo-2-mercaptomethylazetidine ci$-3-0-formylmandelamido-4-oxo-2-mereaptomethylazetidine cis-3-(q-t-butoxvcarbonvlamlnophenvlacetamldo)-4oxo-2-mercaptomethylazetidine cis-3-isobornyloxycarbonylamino-4-oxo-2-mercaptomethylazetidine cls-3-(p-methoxybenzyloxycarbonylamino)-4-oxo-2mercaptomethylazetidine cls-3-benzyloxycarbonylamino-4-oxo-2-mercaptomethylazetidine _ 39 _ 8 45 Similarly when the triphen^lmethylthiomethyl derivatives prepared in Preparation/ are deblocked by the 31 procedure set forth in Preparation /the corresponding mercaptomethyl compounds are obtained.

PREPARATION 31. of A solution/methyl cis-3-(4.5-diphenyl-2-oxo-4-oxazolin-3~yl)-4-oxoazetidine-2-carboxylate(2.0 g, 3.9 mmol) in 50 ml ethanol is added to 10% Pd on carbon (0.5 g) which is premoistened with 2 ml 2N HC1. The mixture is hydrogenated for 12 hours at 50 psi and 40°G. After filtration, the solvent is removed and the oil is dissolved in methylene chloride which is then washed with NaHCOj and brine and dried. The solution is evaporated to give methyl cis-3 -amino- 4-oxoazeti di ne-2 -carboxyl ate. 438 45 PREPARATION 32.

Trichloroethyl 7g-L.-butoxycarbonvlamino-6aH-2-hydroxy-8ΟΧΟ-4-ίΙΐΐΗ-1-3Ζ3ί>1σγθ1.θί4.2.ΰ]θ£ΕΑη6-2-ΟΑΓί>ΟΧν]-3ϋ6 To a suspension of 122 mg (0.52 mmole) of cis-35 £-butoxycarbonylamino-4-oxo-2-mercaptomethylazetidine in ml of methylene chloride is added 156 mg (0.52 mmole) 2,2,2of/trichloroethyl bromopyruvate followed at 0 by 50 μΐ of triethylamine. Methanol (5 ml) is added to effect dissolution and the mixture is stirred at room temperature for 1 hour. The solvents are removed in vacuo, the residue is dissolved in ethyl acetate which Is washed with dilute HCI, 5% NaHCOg and brine; dried over magnesium sulfate and evaporated to dryness. The residue is chromatographed over silica gel with 1:2 ethyl acetate15 benzene to afford 80 mg (35%) of the title product as a mixture of diastereomers.

EXAMPLE T, 2,2,2-Trlchloroethyl 73-amino-6aH-8-oxo-4-thia-l-azabicyclo14'. 2.0] oct-2-ene-2-carboxylate Method A: To a solution of 70 mg (0.156 mmole) of the 32 product from Preparation/ £n 3 ml of dry ethyl acetate is added 0.2 ml pyridine and 150 mg of methanesulfonic. anhydride. The mixture is stirred overnight at room temperature and then diluted with water. The aqueous solution is extracted with ethyl acetate and the extracts are washed with dilute HCI and 5% NaHCQj and then dried. Evaporation gives a residue which is chromatographed on silica gel with 80:20 benzene-ethyl acetate as eluant.

The product (50 mg) is a mixture of . 2,2,2-trichloro30 ethyl cis-7-t-butoxycarbonvlamino-8-oxo-4-thla-l-azablcyclo“ corresponding [4.2.0]oct-2-ene-2-carboxylate and the/7-methylsulfonylamino - 41 4 3 8 4 5 compounds but separation before the following deblocking reaction Is not necessary.

The above mixture is dissolved in 2 ml of methylene chloride, cooled to 0° and treated with 0,5 ml trifluoroacetic acid for 0.5 hr at 0°. The solution is washed with 5% NaHCOg and then extracted with dilute HCl. Tile aqueous phase is neutralized and extracted with ethyl acetate. The extracts are dried and then acidified with ethereal HCl. The hydrochloride salt of the title product is collected.

Method B: To a solution of the product from Preparation 32 (150 mg) in ethyl acetate (4 ml) is added pyridine (150 /il) o for The solution is cooled to -10 C, stirred/1 hour with thionyl^ chloride (50jql), diluted with water, acidified and extracted with ethyl acetate. The extracts are washed with 5% NaHCOg, and brine, dried and evaporated. The product is purified and deblocked as in Method A. 3 8'».* EXAMPLE 2 When cis-3-t-butoxycarbonylamino-4-oxo-2-mercaptomethylazetIdine is condensed with benzhydryl bromopyruvate 32 by the procedure of Preparation/ benzhydryl 7β-t-butoxycarbony lamino-6ccH-2-hydroxy-8-oxo-4- thia-l-azab ieyclo[4.2.0]octane-2-carboxylate is obtained. Dehydration by either of the methods set forth In Example 1 gives benzhydryl 7B-ti-butoxycarbonylamino-6aH-8-oxo-4-thia-lazabicyclo[4.2.0]oct-2-ene-2-carboxylate.

Similarly as described above, use of t-butyl bromopyruvate gives the two compounds described above as their t-butyl esters.

EXAMPLE 3 7£-Amlno-6aH-8-oxo-4-thla-l-azabicyclo[4.2.0loct-2-ene-2ca'rbo'xyllc acid Method A - 2,2,2To a solution of 43 mg (0.1 mmole) of/trichloroethyl cls-7-t-butoxycarbonylamino-8-oxo-4-thla-1-azabicvclo[4.2.0]oct-2-ene-2-carboxylate in 6 ml of dimethylformamide and 6 ml of acetic acid is added over a 1.5 hr period 250 mg (3.8 mmole) zinc dust. The mixture is stirred vigorously for 3 hrs and then diluted with 50 ml of water. The mixture is acidified with dilute HC1, filtered and extracted with ethyl acetate. The organic phase is extracted with 5% NaHCOg which is acidified and reextracted into ethyl acetate. The final extracts are washed with brine, dried, and evaporated to give cis-7-t-butoxycarbonylamino8-oxo-4-thia-l-azabicyclo[4.2.0]oct-2-ene-2-carboxylic acid.

The above product is dissolved in methylene chloride and treated with trifluoroacetic acid as - 43 43 8 45 mixture outlined in Example 1. The reaction/is evaporated in vacuo and the residue is triturated with ether to give the trifluoroacetate salt of the title product. The salt is dissolved in water and treated with basic ion-exchange 5 : Amberlite is a Registered Trade Mark resin (Amberlite IR-45/) until constant pH is obtained. After filtration, the aqueous solution is lyophilized to give the title product.

Method B 2,2,2The ethyl acetate solution of /trichloroethyl cLs“7/3-amino-6aH-8-0xo-4-thia-l-azabicyclo[4.2.0]oct-2ene-2-carboxylate from Example 1, is treated with acetic acid and zinc dust as described above in Method A. After for stirringβ hrs, the reaction solution is acidified to pH 2 with dilute HCl, filtered, and evaporated to dryness.

The residue is treated with basic ion-exchange as in Method A to give the title product.

Method C A solution of benzhydryl 73-t-butoxycarbonylamino-6aH-8-oxo-4-thia-1-azabicyclo[4.2.0]oct-2-ene-2) carboxylate (1 mmol) in methylene chloride is treated with trifluoroacetic acid at 0° as in Example 1, to cleave the - 44 4 3 8 4 5 PREPARATION 33, Benzhydryl 7ff-phenoxyacetamido-6ctH-2-hydroxy-3-methyl-8-oxo-4To a stirred solution of 0.234 g (0.88 mmol) of cls-3-phenoxvacetanndo -4-oxo-2-mercaptomethylazetidIne aid 0.304 g (0.88 mmol) benzhydryl 3-bromo-2- oxobutyrate in 26 ml of dry methylene chloride is added 122^1 (0.88 mmol) of triethylamine at room temperature under argon. The solution is stirred for 1 hr, then the methylene chloride is removed in vacuo and the residue dissolved in ethyl acetate. The ethyl acetate solution is washed with 3N HC1 solution, 57. NaHCOg solution and saturated NaCl solution.

After drying, the solution is evaporated in vacuo to give 0.531 g of crude product. Chromatography of 0.466 g of crude product on silica gel, eluting with ethyl acetatehexane , affords 320 mg of benzhydryl 7£-phenoxyacetamido6aH-2-hydroxy-3-methyl-8-oxo-4-thia-l-azabicyclo[4.2.0]octane2-carboxylate as a foam. (78%) PREPARATION 34.

Benzhydryl 7j3-phenoxyacetamldo-6aH-3-methyl-8-oxo-4-thla-lazablcyclol4.2.0]oct-2-ene-2-carboxylate To a stirred solution of 0.200 g (0,39 mmol) of benzhydryl 7 0-phenoxyacetamido-6aa-2-hydrcKy-3-ffietiyl-8-oxo-4thia-l-azabicyclo[4.2.0]octane-2-carboxylate and 282 /,1 trifluoroacetic athydride in 4 ml of dry ethyl acetate is added dropwise 161 μ! (2.0 mmol) pyridine at 0° under argon. The solution is allowed to come to room temperature and stirred for 20 hours. The reaction mixture is diluted with ethyl acetate and washed twice with 5% NaHCOg, 3N HC1, and brine. The ethyl acetate layer is dried over MgSO^ and concentrated in vacuo to afford 300 mg crude product. Chromatography on silica geL eluting with 50:50 - 45 _ 438 45 ethyl acetate/benzene gives 2L8 mg (11 %) of white, crystalline benzhydryl 70-phenoxyacetsmido-6aH“3-methyl -8-oxo-4-thia-lazabicyclo[4.2.0]oct-2-ene-2-carboxylate and 42.1 mg (21%) of recovered starting material, mp 155-156°.

EXAMPLE 4 7g-Phenoxvacetamido-6aH-3-methyl-8-oxo-4-thia- 1-azabicycloTA.^.Ojoct-Z'-ene'^-carb'oxylic acid A solution of 0.062 g (θ·12 mmol) of benzhydryl 7p-phenoxyacetamido-6aH-3-methyl-8-oxo-4-thia-lazabieyclo[4.2,0]oct-2-ene-2-carboxylate, 125 yul anisole, and 0.7 ml of trifluoroacetic acid In 2 ml of methylene o chloride is stirred at 0 under argon for 1.3 hours. The trifluoroacetic acid and methylene chloride are removed in vacuo and the residue is treated with ethyl acetate and dilute HCI. The ethyl acetate is extracted with 5% MaHCOg, and the aqueous combined extracts acidified to a pH of 1.5 and reextracted into ethyl acetate. The combined organic extracts are dried over MgSO^, filtered and concentrated. After pumping under high vacuum, 25.2 mg of a yellow solid is isolated. Precipitation from methylene chloride-hexane solution afforded 18.7 mg (44%) of analytically pure title compound, mp 205-15‘’(dec).

PREPARATION ~35. χ-Butyl 7g-phenoxyacetamido-6c(H-2-hydroxy-3-methvl*-8-oxo-4-t3iial-azabicycIol,4.2.0Joctane-2'-carboxylate To a stirred solution of 0.083 g (0.31 mmol) of cis-3-phenoxyacetamido-4-oxo-2-mercaptomethylazetidine and 0.084 g (0.31 mmol) t-butyl 3-bromo-2- oxobutyrate in 10 ml of dry methylene chloride is added 44 jul (0.31 mmol) of triethylamine at room temperature under argon. The solution is stirred for 1.25 hours, the methylene chloride removed in vacuo, and the residue dissolved in ethyl - 46 _ 4384» solution acetate. The ethyl acetate/Is washed with 3N HC1, 57.

NaHCOg and brine. After drying, the solution is evaporated in vacuo to give 0.120 g of crude product. Chromatography on silica gel eluting with 50:50 ethyl acetate-hexane $ gives 93.8 mg (70%) of a colorless oil. After standing at room temperature, the oil solidified to give the crystalline title compound, mp 138-150°.

PREPARATION -36. i-Butyl 7/3-phenoxyacetamldo-6aH-3-methyl-8-oxo-4-thia-l10 azabicyclo(4.2.0]oct-2-ene-2-carboxylate To a stirred solution of 0.302 g (0.72 mmol) of 34 the 2-hydroxy compound from Preparation/ and 200 /jl (1.43 mmol) of trifluoroacetic anhydride in 6 ml dry ethyl acetate is added dropwise 290yql (3.58 mmol) of pyridine at 0° under argon. The solution is allowed to come to room and temperature /stirred overnight (20 hrs). The reaction mixture is diluted with ethyl acetate and washed with 5% NaHCOg, 3N HC1 and brine. The ethyl acetate solution is dried over MgSO^ and concentrated. Chromatography on silica gel,eluting with ethyl acetate-hexane mixture· affords 49.5 mg (17 %) of the title compound as a yellow solid, mp 147-149°. - 47 _ EXAMPLE S Substitution of ci3-3°t-butoxvcarbonvlamlno-4oxo-2-mercaptomethylazetidine for the phenoxyacetamido of derivative in the procedures/ Preparations 33 and 35 gives the benzhydryl and j>butyl esters of 70-_t-butoxvcarbonylamino-0aH-2-hydroxy-3-methyl-8-oxo-4-thia-l-azahicyclo[4.2.0]octane-2-carboxylfc acid.

The above esters are each treated with trifluoroin acetic anhydride by the procedure/ Preparations 34 and 36 or with the other dehydrating agents set forth in Example 1 to give benzhydryl and tfbutyl 70-Jfc-butoxycarbonylamino6aH-3-methyl-8-oxo-4-thia-l-azabicyclo[4.2.0]oct-2-ene-2carboxylate.

Treatment of either of the above esters with trifluoroacetic acid by the procedure in Example 4 gives 70-amino-6aH-3-methyl“8-oxo-4-thia-l-azabicyclo[4.2.O]oct- i t 2-ene-2-carboxylic acid. .

PREPARATION 37.

£,-Butyl 70-phenoxyacetamido-6aH-3-bromomethyl-8-oxo-4-thia1-azabic'yclo L'4.2'. 0) oct-2-ene-2-carboxylate A suspension of 30.0 mg (0.075 mmol) of t^-butyl 70-phenoxyacetaraido-6dH-3-methyl-8-oxo-4-thia-l-azabicyclo[4.2.0]oct-2-ene-2-carboxylate and 28 mg (0.15 mmol) of N-bromosuccinimide in 5 ml of carbon tetrachloride is degassed, a trace of azobisisobutyronitrile is added and the mixture refluxed for 2 hrs. After cooling, the mixture is filtered, evaporated to dryness, redissolved in ethyl acetate, washed with 5% sodium bisulfite, dried over magnesium sulfate and evaporated to dryness. The residue was chromatographed on silica gel with 5% ethyl acetate in chloroform to give, on trituration with methylene chloride-hexane, 10.8 mg of the title compound as a pale yellow amorphous solid.

EXAMPLE 6 7g-Fhenoxyacetamldo-6aH-3-acetoxymethyl-8-oxo-4-thla-lazablcycl0L4.2.0]oct-2-ene-2-carpoxyric acid A mixture of 48 mg (0.1 mmol ) of the b»mo37 methyl derivative from Preparation/ and 200 mg of silver acetate in 10 ml of acetone is stirred at room temperature for 1 day. The mixture is filtered, the fLltrate is evaporated to dryness and chromatographed over silica gel with 5% ethyl acetate in chloroform to afford the .t-butyl ester of the title compound.

The above material is dissolved in ice cold trifluoroacetic acid containing 107. anisole. The solution is stirred at 0° for 1/2 hr, the solvent is removed in vacua, the residue Is dissolved tn ethyl acetate and extracted with 57» sodium bicarbonate solution. The aqueous extract is carefully acidified and extracted with ethyl acetate, the extract is dried over magnesium sulfa.te and evaporated to dryness. Trituration with hexane 43848 EXAMPLE 7.

When . t-butyl 7£-t_“butoxycarbonylamIno-6aH-3methyl-8-oxo-4-thia-1-azabicyclo[4.2.0]oct-2-ene-2carboxylate is treated with N-bromosucciniraide by the pro5 37, cedure-of Preparation/ . tobutyl 73-t-butoxycarbonylamino6dH-3-bromomethyl-8-oxo-4-thla-l-azabicyclo[4.2.0]oct-2ene-2-carboxylate is obtained.

Treatment of the above bromomethyl derivative with sodium acetate or silver acetate according to the procedure of Example 6 gives tobutyl 73-t.-butoxycarbonylamino-6aH-3-acetoxymethyl-8-oxo-4-thia-1-azabicyclo [4.2.0]oct-2-ene-2-carboxylate When the above compound is treated with trifluoro acetic acid by the procedure of Example 6, 7j3-amino-6ctH3-acetoxymethyl-8-oxo-4-thia-l-azabicyclo[4.2.0]oct-2-ene2-carboxylic acid is obtained.

PREPARATION 38. 2,2,2-Trichloroethyl 7p-Pheno:ryacetamido-6_aH-2-hydroxv-8-oxo-420 To a solution of 273 mg (1.02 mmol) of cls-3phenoxyacetamido-4-oxo-2-mercaptomethylazetidine and 305 mg 2.2.2— (1.02 mmol) of/trichloroethyl bromopyrwate in 30 ml of methylene chloride is added slowly at 0°, 0.110 ml triethyl amine. After stirring for too hours at room temperature, the mixture Is evaporated to dryness, the residue is dissolved in ethyl acetate, washed with 5% HCI, 5% NaHCOg, and saturated NaCl, evaporated to dryness and chromatographed over silica gel with 1:1 ethyl acetatehexane as eluant to give the title product, 256 mg (52%).

TV -50 43 Sd G EXAMPLE 8 73-Phenoxvacetamido-6aH-8-oxo-4-thla-l-azablcyclo[4.2.0]oct; Z-ene-A-carboxyl'lc acid To a cooled solution (0° ) of 0.477 g (1 mmol) 2,2,25 of/trichloroethyl 7)3-phenoxyacetamido-6aH-2-hydroxy-8-oxo4-thia-l-azabicyclo[4.2.0]octane-2-carboxylate in 10 ml ethyl acetate is added 65 μΐ of trifluoroacetic anhydride mixture and then 362 ^1 of pyridine. The reaction/is stirred overnight at room temperature and then diluted with ethyl acetate. The solution is washed with NaHCOg solution, 3NHCland saturated saline solution. The dried solution is evaporated to give the ester of the title product which is reerystallized from benzene; 157 mg (34%).

In 24 ml solution of dimethylformamide-glacial acetic acid (1:1) is dissolved 70 mg of the above ester.

To this solution is added over a 1.5 hour ’period 500 mg of zinc dust which has been treated with 5% HG1 for 3 minutes, washed with water, ethanol, and ether and then for dried. The reaction mixture is stirred/3 hours at room temperature, diluted with water, acidified with 3N HC1 and extracted with ethyl acetate. The extracts are washed with a large volume of 5% NaHCOg. The aqueous solution Is acidified to pH 2 with HC1 and extracted with ethyl acetate. The dried extracts are concentrated in vacuo and then high vacuum is used to remove residual acetic acid. The residue is triturated with ether-hexane, dissolved in methylene chloride and precipitated with hexane to give the title product, mp 194-5°(dec).

EXAMPLE 9 7j3-(g-Aminophenylacetamido)-6aH-8-oxo”4-thia-l-asablcycloL4.2.0joct-2-ene-2-caAoxyjLic acid Benzhydryl bromopyruvate (500 mg) was dissolved in benzene (8 ml) and tetrahydrofuran (1 ml), cooled to ° and treated with a solution of diphenyldiazomethane (286 mg) in benzene (10 ml). The solution is Stirred until colorless and then evaporated to dryness. The residue is dissolved in methylene chloride (5 ml) and cooled to 0° and then cis-3-(q-fc-butoxvcarbonvlaminophenvlacetamido)-4-oxo-2-mercaptomethylazetidine (465 mg) is mixture added. The reaction/is stirred for one hour and evaporated to dryness to give a residue which dissolved in ethyl acetate-water. The ethyl acetate phase is washed with 1% HCl, WaHCOg solution and NaCl solution. The dried organic phase is evaporated to give benzhydryl 7-(a-t>butoxycarbonylaminophenylacetamido)-2-hydroxy-8-oxo-4-thia-lasabicyclo[4.2.0]octane-2-carboxylate.

To a solution of the above product (200 mg) in ethyl acetate (4 ml) is added pyridine (150 ^1). The for solution is cooled to -10° , stirred/one hour with thionyl chloride (50 /4,1), diluted with water, acidified and extracted with ethyl acetate. The extracts are washed with 5% NaHCOj and NaCl solution, dried and evaporated.

The residue is chromatographed over silica gel with 5:1 benzene-ethyl acetate as eluant to give the blocked derivative of the title product (50 mg).

The blocking groups are removed by stirring a solution of the above product (118 mg) in methylene chloride (10 ml), anisole (0.2 ml) and trifluoroacetic acid (2.0 ml) for 45 minutes at 0° under argon. The . 52 mixture reaction/is allowed to warm to room temperature and then is evaporated to dryness under high vacuum. The trifluoroacetate salt of the title compound is triturated with ether and reprecipitated from methanol-ether.

EXAMPLE TO 7g-(q-Aminq-ja-hydroxyphenylacetamido)-6dH-8-oxo-4-thia-lazaDtcvclo[4.2.0Joct-2-ene-2-carboxylic acid To a solution of 265 mg (1 mmol) of N-t-butoxycarbonyl-p-hydroxyphenylglycine in dry tetrahydrofuran (10 ml) is added triethylamine (0.14 ml). After cooling to -10°, isobutyl chloroformate (1 mmol) in 2 ml of mixture tetrahydrofuran is added dropwise and the reaction/is for stirred/20 minutes. A mixture of 270 mg (1 mmol) of cis3-amino-4-oxo-2-azetidinemethyl tosylate and 0.14 ml of triethylamine in 50% aqueous tetrahydrofuran (5 ml) is cooled to -10° and added to the reaction solution. The for resulting solution is stirred/one hour at low temperature and then allowed to warm to room temperature. The organic solvent is removed and the aqueous residue is diluted with water and extracted with ethyl acetate. The aqueous solution is layered with ethyl acetate, cooled and acidified. Phases are separated and the aqueous layer is extracted with ethyl acetate. The dried organic layers are evaporated to give the cis-3-(a-t-butoxvcarbonylaminop-hydroxyphenylacetamido)-4-oxo-2-azetidinylmethyl tosylate.

The above tosylate is reacted with Nal followed by p-methoxybenzyl mercaptan according to the procedure 24 of Preparation/ to give the ρ-methoxybenzylthto derivative “* 28 which IS cleaved by the procedure of Preparation/ to give cis-3-(α-t-butoxycarbonylamino-p-hydroxyphenylacetamido)- 53 _ 8 & 8 4-oxo-2-mercaptomethylazetidine.

The above product is reacted with benzhydryl bromopyruvate according to the procedure of Example 9 and the subsequent reaction sequence disclosed therein is continued to give the title product.

EXAMPLE Π 7j3-(2-Thienylacetamido)-6aH-8-oxo-4-thia-l-azabicyclo1*4.2.0j'oct-2-ene-2-carbo'xyIic acid : The dry ethyl acetate solution(from Example 1) 2,2of/trichloroathyl 7£-amino-6aH-8-oxo-4-thia-l-azabicyclo[4.2.0]oct-2-ene-2-carhoxylate>which is obtained from 120 mg of the t-hutoxycarbonyl derivative is treated with 0.2 ml 2-thienylacetyl chloride and 0.2 ml of triethylmixture for amine. The reaction/is stirred/2 hours at room temperature and then diluted with NaHCOg solution. The organic layer is separated, washed with 3N HC1, dried, and evaporated 7to give the/(2-thienylacetamido derivative.

The above ester is treated with zinc dust and acetic acid according to the procedure in Example 8 to give the title product.

EXAMPLE 12 7j3-Phenoxyacetamido°6aH-8-oxo-4-thia-l-azabicvclo[4.2,0]oct-2“ene°2°carboxylic acid 2,2,2The dry ethyl acetate solution of/trichloroethyl 70-amino-6aH-8-oxo-4-thia-l-azahicyclo[4.2.0]oct-2ene-2-carboxylate from Example 29 is cooled to 0° and treated with one equivalent each of phenoxyacetyl chloride and triethylamine. After stirring one hour, the mixture is washed with dilute HC1 and brine. The organic phase is 2,2,2dried and evaporated to give /trichloroethyl ester of the title product. _ 54 438 45 2,2,2The/trichloroethyl ester was treated with zinc dust and acetic acid by the procedure given in Example 11 to give the title product.

EXAMPLE 13 7£-Methvlsul£onvlacetamido-6aH-8-qxo-4-thia-l-azabicvclol4.2.0Joct-2-ene-2-carboxylic acid 2,2,2A solution of 200 mg (1 mmol) of/trichloroethyl 73-amino-6dH«8-oxo-4-thia-l-azabicyclo[4.2.0]oct-2-ene-2carboxylate and 0.14 ml triethylamine in 10 ml of dimethylformamide is stirred with 236 mg (1 mmol) of the N-hydroxysuccinimide ester of methylsulfonylacetic acid for two hours at room temperature. The reaction is poured into ice water and the resultant solution is extracted with ethyl acetate. The aqueous phase is acidified to pH 2 and extracted with ethyl acetate. The dried extracts are evaporated to give the ester which is deblocked as in Example 8 to give the title product.

EXAMPLE 14 2,2,2When/trichloroethyl 7B-amino-6dH-8-oxo-4-thia-l20 azabieyelo[4.2.0]oct-2-ene-2-carboxylic acid is acylated with one of the following carboxylic acids: α-formyloxyphanylacetic acid trifluoromethylmercaptoacetic acid methylmercaptoacetic acid 2,2,2-trifluoroethylsulfinylacetic acid cyanoacetic acid cyanomethylmercaptoacetic acid cyanomethylsulfinylacetic acid cyanomethylsulfonylacetlc acid a-carboxy-2-thienylacetic acid a-carboxy-3-thienylacetic acid -.55 43845 α-sulphophenylacetic acid 3-thienylacetic acid 1-tetrazolylacetic acid using the acid or an activated derivative thereof, all of which are known in the art, and which have any sensitive or interfering group suitably protected, according to known acylation procedures such as those set forth in Examples 10 to 13, followed by removal of all protecting groups by standard methods, gives the corresponding 70-acylamino-6ctH-8-oxo-4-thla-l-azabicyclo[4.2.O]oct-2-ene-2-carboxylic acid.

EXAMPLE 15 When a-(N-jt-butoxycarbonylamino)-4-hydroxy-3fluorophenylacetic acid or a-(N-t_-butoxycarbonylamino)-4(tybutoxycarbonylmethylamino)phenylacetic acid is substituted for N-t-butoxycarbonyl-p-hydroxyphenylglycine in Example 10, the following compounds are obtained: 70»(a-amino-4-hydroxy-3-fluorophenylacetamido)-6oH-8-oxo-4-thia-l-azabicycloi4.2.0]oct-2-ene-2-carboxylic acid 70-(α-amino-4-carboxymethylaminophenylacetamido)-6aH-8-oxo-4-thia-l-azabicvclo[4.2.0]oct-2-ene-2-carhoxylic acid. 4384C EXAMPLE 16 7A-(q-Carboxyphenylacetamido)-6aH-8-oxo-4-thia-l-azablcyclo [4.2.0joct-2-ene-2-carboxyllc acid Equimolar quantities of the N-hydroxysuccinimide ester of o-£-butoxycarbonylphenylacetic acid, cis-3-amino-4 oxo-2-azetidinylmethyl tosylate and triethylamine are stirred together in dimethylformamide for two hours at mixture room temperature. The reaction/is poured into ice water and the aqueous solution is washed with ethyl acetate, acidified to pH 2 and extracted with ethyl acetate. The dried extracts are evaporated to give the cis-3-(a-tbutoxycarbonylphenylacetamido)-4-oxo-2-azetidinylmethyl tosylate.

When the above tosylate is substituted for the tosylate in Example 10 and the reaction sequence disclosed therein is continued, the title product Is obtained. 438 4 5 EXAMPLE 17 When 7^-amino-6aH-3-msthyl“8-oxo-4-thia-lazabicyclo[4.2.0]oct-2-ene-2-carhoxylic acid is acylated with 2-thienylacetic acid, phenoxyacetic acid, methylsulfonylacetic acid, α-formyloxyphenylacatic acid, trifluoromethylmercaptoacetic acid, 2,2,2-trifluoroethylsulfinylacetic acid, cyanoacetic acid, cyanomethylmercaptoacetic acid, cyanomethylsulfinylacetic acid, cyanomethylsulfonylacetic acid, a-carboxy-2-thienylacetic acid, a-carboxy-3thienylacetic acid, α-sulphophenylacetie acid, 3-thienylacetic acid, 1-tetrazolylacetic acid, a-aminophenylacetic acid, a-araino-jj-hydroxyphenylacetic acid, a-amino-4hydroxy-3-£luorophenylacetic acid, a-amino-p-carboxymethylarainophenylacetic acid, or α-carboxyphenylacetic acid, using the acid itself or an activated derivative thereof, all of which are known in the art and which have any sensitive or interfering . groups suitably protected, according to known acylation procedures such as those set forth in Examples 10 to 13, followed by removal of all protecting groups by standard methods, the corresponding 73-acylamino-6aH-3-methyl-8-oxo-4-thlal-asabicyclo[4.2.0]oct-2-ehe-2-carboxylic acid is obtained.

EXAMPLE 18 When 73-amino-6atl-3-acetoxymethyl-8-oxo-4-thia-lazabicyelo[4.2.0]oct-2-ene-2-carboxylic acid is acylated with 2-thienylacetic acid, phenoxyacetic acid, methylsulfonyl acetic acid, α-formyloxyphenylacetic acid, trifluoromethylmercaptoacetie acid, 2,2,2-trifluoroethylsulfinylacetic acid, cyanoacetic acid,cyanomethylmercaptoacetic acid, cyanomethylsulfinylacetic acid, eyanomethylsulfonyl. 58-4 3845 acetic acid, a-carboxy-2-thienylacetic acid, a-carboxy-3thienylacetic acid, α-sulphophenylacetic acid, 3-thienylacetic acid, 1-tetrazolylacetic acid, a-aminophenylacetic acid, α-amino-p-hydroxyphenylacetic acid, a-amino-45 hydroxy-3-fluorophenylacetic acid, a-amino-p-carboxymethylaminophenylacetic acid, or α-carboxyphenylacetie acid, using the acid itself or an activated derivative thereof, all of which are known in the art and which have any sensitive or interfering groups suitably protected, according to known acylation procedures such as those set forth in Examples 10 to 13, followed by removal of all protecting groups by standard methods, the corresponding 7j3-acylamino-6aH-3-acetoxymethyl-8-oxo-4-thia-lazabicyclo[4.2.0]oct-2-ene-2-carboxylic acid is obtained.

Claims (18)

1. >4S T WE CLAIM IS:

1. A thia-azabicyclooetene compound of the structural formula Η H RNT - ' Λ COOH where R is a carboxylic acyl group other than phenylacetyl and E is hydrogen, methyl, bromomethyl, or lower alkanoyloxymethyl.

2. A compound as claimed in Claim 1, in which R is XCflt'ZCO-, YCHgCO- or ZS(O) n CH 2 CO-, where X is thienyl, cyclohexyl, cyclohexenyl, cyclohexadienyl, phenyl, or phenyl substituted by one or two substituents selected from lower alkyl, lower alkoxy, hydroxy, hydroxymethyl, halo, nitro, amino, aminomethyl, marcapto, lower alkylthio, trifluoromethyl, ureido, formamido and carboxymethylamino; W is hydroxy, amino, formyloxy, carboxyl, or sulfonic acid; Y is cyano, azido, phenoxy, or a 5- or 6- membered heterocyclic group containing from 1 to 4 hetero atoms selected from nitrogen, oxygen and sulfur, such heterocyclic group being unsubstituted or substituted with one or two substituents selected from lower alkyl, lower alkoxy, hydroxy, halo, nitro, amino, aryl and lower aralkyl; Z is phenyl, pyridyl, lower alkyl, trifluoromethyl, trifluoroethyl or cyanomethyl, and n is 0, 1 or 2; and E is hydrogen, methyl, or acetoxymethyl.

3. A compound as claimed in Claim 2, where R is XCHWCO-.

4. A compound as claimed in Claim 3, where X is thienyl, phenyl, p-hydroxyphenyl, 4-hydroxy~3-fluorophsnyl, or 4-carboxymethylaminophenyl.

5. A compound as claimed in Claim 4, where W is hydroxy or amino. -6043845 j 1 Γ -

6. 7/S-(o6-AminGphenylacetamidQ)-6*H-8-QXQ-4-thia-lj&zabicyclo/4.2.07oct-2-ene~2--carboxylic. acid.

7. 7/3-(»«-Amino-£-hydroxyphenylacetamido)-6i*H-

8. Oxo-4-thta-l-azabicyclo/4.2.07oct-2-ene-2-carbnxylie acid. 5 8. A compound as claimed in Claim 2, where R is YCHgCO-.

9. A compound as claimed in Claim 8, where Y is cyano, azido, phenoxy, thienyl, tetrazolyl or sydnonyl.

10. 7/3-Phenoxyacetamido-6«H-8-oxo-4-thia-l-aza10 bicyclo/4.2.Q7oct-2-ene-2-carboxylie acid.

11. 7/J-Phenoxyacetamido-6«H-3-methyl-8-oxo-4-thia-lazabicyclo/4.2.07oct“2-ene-2-carboxylic acid.

12. ^3-(Phenoxyacetamido-6*H-3-acetoxymethyl-8oxo-4-thia-l-azabic.yclo/4.2.Q7oct-2~ene-2-carboxylic 15 acid.

13. 7/5-(2-Thienylacetamido)-6*H-8-oxo-4-thia-lazabicyclo/4.2.07oct-2-ene-2-carboxylic acid.

14. A compound as claimed in Claim 2, where R is ZS(0) n CH 2 C0-. 2Q 15. A compound as claimed in Claim 14, where Z is phenyl, pyridyl when n is 0, methyl, tri fl uoromethyl, trifluoroethyl, or cyanomethyl.

15. 7/5-Methylsulfonylaeetatnido-6*H-8-oxo-4-thia-lazabicyclo/4.2.07oct-2-ene-2-carboxylic acid. 25 17. Any one of the compounds according to Claim 1 of Examples 14 to 18.

16. 18. A process for preparing a compound according ( to Claim 1, substantially as described in any one of Examples 4, 6 and 8 to 18. -614 3 8 4S

17. 19. A thia-azabicyclooctene compound of the structural formula COOR 2 where E is hydrogen, methyl, bromomethyl or lower 5 alkanoyloxymethyl; each R 1 is hydrogen or a monovalent removable amino-protecting group, or both R 1 groups taken together form a divalent removable amino-protecting group; and R is hydrogen or a removable carboxyl-protecting group. 3 20. A compound as claimed in Claim 19, where E is hydrogen. 21. A compound as claimed in Claim 19, where E is methyl. 22. A compound as claimed in Claim 19, where E i is acetoxymethyl. 23. . A compound as claimed in any one of Claims 19 to 22 where each R 1 is hydrogen. 24. A compound as claimed in any one of Claims 19 to 22 where either one R 1 is hydrogen and the other is t-butoxycarbonyl,· trichloroethoxycarbonyl, benzyloxycarbonyl, Ό-methoxybenzylcarbonyl, isobornyloxycarbonyl, trityl, or l-methoxycarbonyl-2-propenyl; or RgN is phthalimido or 4,5-diphenyl-2-oxo~4-oxazolin-3-y1. 25. A compound as claimed in any one of Claims 19 to 24, where R is hydrogen, 2,2,2-trichloroethyl, t-butyl, benzyl, benzhydryl, benzyloxymethyl, p-nitrophenyl, £-methoxyphenyl, p-nitrobenzyl, or p-methoxybenzyl. 26. 2,2,2-Trichloroethyl 7/?-amino-6<*H-8-oxo-4-thia1-azabicyclo/4.2.07oct-2-ene-2-carboxylate. -624 38 15 £ 27. 7/3-Amino-6«H-8-oxo-4-thia-l-azabicyclo/4.2.Q7pt-2-ene-2-carboxylie acid. 28. Benzhydryl ^l-t-butoxycarbonylamino-6<*H-8-oxo4-thia-l-azabicyclo/4.2.07oct-2-ene-2-carboxylate. 29. t-Butyl 7/?-t-butoxycarbonylamino-6*H-8-oxo-4j;hia-l-azabicyclo/4.2.o7oct-2-ene-2~carboxylate. 30. Benzhydryl TJ-t-butoxycarbonylamino-GoiH-3methyl-8-oxo-4-thia-l-azabicyclo/4.2. o7oct-2-ene-4carboxylate. 31. t-Butyl 7y3-t-butoxycarbonylamino-6*H-3-methyl8-oxo-4-thia-l-azabicyclo/4.2.07oct-2-ene-2-carboxylate. 32. 7/3-Amiho-6«H-3~methyl-8-oxo-4-thia-l-azabicyelO/4.2.07oct-2-ene~2-carboxylic acid. 33. t-Butyl 7/S-t-butoxycarbonylamino-6*H-3-acetoxy15 methyl-8-oxo“4“thia“l-azabieyclo/4.2.07oct-2-ene-2carboxylate. 34. 7^-Amino-6« 35. A process for preparing a compound according

18. 20 to Claim 19, substantially as described in any one of Examples 1,2,3,5 and 7.