NO842882L - PROCEDURE FOR THE PREPARATION OF ANTI-BACTERIAL 2-HETEROCYCLYLKYLTIOPENEM DERIVATIVES - Google Patents

Description

This invention relates to a method for preparing a group of antibacterial agents containing a 2-azetidinone (betalactam) ring. Chemically, the antibacterial agents prepared according to this invention are identified as 6-alpha-hydroxyethyl-2-substituted-2-penem-3-carboxylic acid compounds.

Although certain 2-substituted-2-penem-3-carboxylic acid compounds have been discussed previously, there is a continuing need for new compounds having desired antibacterial therapeutic properties.

The present invention relates to the manufacture

of the compound with formula

or a pharmaceutically acceptable salt thereof, wherein

R is -(alk)-X-R 1

where X is imidazolyl, 1,2,3-triazolyl, 1,2,4-triazolyl or tetrazolyl; R^ is hydrogen or alkyl having 1-4 carbon atoms,

and alk is the alkylene having 1-4 carbon atoms, and

R2 is hydrogen or a group that forms an ester that is hydrolyzed in vivo.

Included within the scope of the present invention,

is the preparation of a compound of formula

or a pharmaceutically acceptable salt thereof, wherein R and R2 are as defined above for compounds of formula I.

Preferred compounds of formula I and II include those wherein X is imidazolyl, and particularly preferred compounds include those wherein R is 2-(imidazol-1-y1)ethyl, (1-methylimidazol-2-yl)methyl, (imidazol-4 -yl)methyl or 1-(imidazol-1-yl)prop-2-yl.

A suitable pharmaceutical composition may contain a compound of formula I or II and a pharmaceutically acceptable diluent or carrier, and may be used to treat a bacterial infection in a mammal by administering an antibacterially effective amount of a compound of formula I or II.

The compounds of formula I and II are useful as antibacterial agents and are derivatives of the bicyclic nucleus of formula:

Throughout this specification, the nucleus of formula III is identified by the name "2-penem" and the ring atoms are numbered as shown. The carbon atom attached to ring carbon 6 is given the number 8. Also, throughout this specification the abbreviation "PNB" is used for the p-nitrobenzyl group.

The relationship between the hydrogen on bridgehead carbon 5 and the remaining hydrogen on carbon 6 in the compound of formula I can be either cis or trans. The present invention encompasses both isomers as well as mixtures thereof. The trans isomers are usually preferred for pharmaceutical use, and the cis isomers can easily be converted to the trans isomers.

Generally, carbon 5 will have the absolute stereochemistry designated R using the Prelog-Ingold R,S stereochemical sign system used in this application. Thus, e.g. a compound of formula II wherein R£ is hydrogen and R is 1-(imidazol-1-yl)prop-2-yl, (5R,6S)-6-(R)-1-hydroxyethyl -2-(1-( imida-

zol-1-yl)prop-2-yl)thio-3-carboxyl-2-penem.

It must be clear that several optically active isomers of the new compounds are possible. The present invention encompasses the preparation of such optically active isomers as well as mixtures thereof.

The present invention relates to the production of penems which are substituted in the 2-position with a group of the general formula -S-(alk)-X-R^. It must be clear that the heterocyclic groups encompassed by X can be attached to alk or R at any imino or methylidene position on the five-membered heterocyclic ring. and (alk) preferably both independently have 1-4 carbon atoms and can be either a straight chain or branched.

The present invention comprises the preparation of the penemr in which the 3-carboxyl group is esterified so that a non-toxic ester group is formed which is hydrolysed in vivo, i.e. in mammalian blood or tissue, and releases the corresponding penem-3-carboxylic acid or a salt of

this. Typical examples of such easily hydrolyzable ester-forming residues are alkanoyloxymethyl, which has from 3-8 carbon atoms, 1-(alkanoyloxy)ethyl, which has from 4-9 carbon atoms, 1-methyl-1-(alkanoyloxy)ethyl, with from 5-10 carbon atoms , alk-oxycarbonyloxymethyl having from 3-6 carbon atoms, l-(alk-oxycarbonyloxy)ethyl having from 4-7 carbon atoms, 1-methyl-l-(alkoxycarbonyloxy)ethyl having from 5-8 carbon atoms, N-(alkoxycarbonyl )aminomethyl having from 3-9 carbon atoms, 1-(N- alkoxycarbonyl amino)ethyl having from 4-10 carbon atoms, 3-phthalidyl, 4-crotonlactonyl, gamma-butyrolacton-4-yl, carboxy-alkylcarbonyloxymethyl1 having from 4 -12 carbon atoms or 5-methyl-2-oxo-1,3-dioxolen-4-yl-methyl.

To prepare the compounds of formula I or II in which R 2 is a group which forms an ester which is hydrolysed in vivo, the acid of formula I or II (R 2 is hydrogen) is reacted with a base so that the corresponding anion is formed. Suitable cations include sodium, potassium, calcium, tetra-alkylammonium and the like. The anion can be prepared by lyophilization of an aqueous solution of I or II, for example an aqueous solution containing tetrahydrofuran and sodium bicarbonate or tetrabutylammonium hydroxide.

The resulting anion from I or II is reacted with the corresponding chloride or bromide from R₂ in a reaction-inert solvent such as acetone or dimethylformamide at about 20 to about 50°C, preferably 25°C.

The compounds of formula I or II where R 1 is hydrogen, or a salt thereof, can be synthesized according to schemes A-C.

As shown in Scheme A, a compound of formula II can be prepared according to the method of Yoshida et al, Chem. Pharm. Bull., 29, 2899-2909 (1981), from the known dibrompenam of formula IV. Dibrompenam (V) undergoes an exchange reaction with t-butyl magnesium chloride at a temperature between about -90 and -40°C, preferably around -76°C, in a reaction-inert solvent such as tetrahydrofuran, diethyl ether or toluene, preferably tetrahydrofuran. Other organometallic reactions can also be used. The resulting reaction mixture is treated in situ with the appropriate aldehyde, e.g. acetaldehyde for the 1-hydroxyethyl deriv. The aldehyde is added between -80 and -60°C, preferably around -76°C for acetaldehyde.

The resulting bromohydroxypenem V is hydrogenated to remove the 6-bromo substituent. A suitable catalyst for the hydrogenation is a noble metal catalyst such as palladium. The reaction is carried out in a protonic solvent such as 1:1 methanol-water or 1:1 tetrahydrofuran-water, preferably 1:1 methanol-water, at a pressure of about 1 to 14 atm., preferably at 4 atm., and a temperature between 0 and 30°C, preferably around 25°C.

The resulting alcohol of formula VI can be protected with a trialkylhalosilane of formula

wherein Rg at any occurrence of an alkyl having from 1 to 6 carbon atoms and Q is chlorine, bromine or iodine. Thus, dimethyl-t-butylchlorosilane in the presence of an amine which is a proton acceptor, such as imidazole, in a polar non-protic solvent such as N,N-dimethylformamide, in a temperature range between about 5 and 40°C forms , preferably around 25°C, a trialkylsilyl which is a hydroxyl protecting group, as shown in formula

VII.

Treatment of VII with mercury(II) acetate in acetic acid at a temperature of around 90°C gives the olefin VIII.

To prepare the desired azetidinone IX, the olefin VIII is ozonized in a reaction-inert solvent such as dichloromethane at a temperature between -80 and -40, preferably around -76°C. The reaction product is treated with an alcohol such as methanol to give the azetidinone IX.

As shown in Scheme B, a compound of formula IX is treated with the trithiocarbonate salt of formula M<+>R^g-S-C(S)-S~ where R^q is alkyl having 1-4 carbon atoms, preferably ethyl, and M is a metal such as sodium or potassium, to produce a compound of formula X. This transfer of IX to X is carried out in an organic solvent or water, preferably a mixture of water and dichloromethane, in a temperature range of about 0-35°C, preferably 25°C.

The compounds of formula X are condensed with p-nitrobenzyl chlorooxalate in the presence of a tertiary alkylamine in which each alkyl has, for example, 1-4 carbon atoms such as ethyl-di-isopropylamine, to prepare the compound of formula XI. This condensation reaction is carried out in a reaction-inert solvent, preferably dichloromethane, in a temperature range of around 5-25°C, preferably around 10°C.

The resulting compound of formula XI is cyclized using a trialkyl phosphite in which alkyl has 1-4 carbon atoms such as triethyl phosphite, in a reaction-inert solvent such as trichloromethane, in a temperature range of about 40-80°C, to give the penem of formula XII .

The thio group in compound XI is oxidized to the corresponding sulfoxide XIII with an oxidizing agent 41 such as m-chloroperbenzoic acid in a reaction-inert solvent such as dichloromethane, in a temperature range around -10 to -30°C, preferably -20°C.

The sulfoxide XIII is substituted with the mecaptide of formula R-S, using e.g. the sodium or potassium salt which is reacted with the sulfoxide XIII in a polar organic solvent such as ethanol or acetonitrile in a temperature range of around 35 to -50°C, preferably around -35°C.

Mercaptans with the formula R-SH, with which it starts, or thioacetates with the formula R-S-C(0)CH3, with which it starts, are known and can be prepared by analogous methods known in the art. For an overview, see J.L. Wardell, "Preparations and Thiols", in The Chemistry of the Thiol Group, S. Patai, editor, John Wiley & Sons, London, 1974, ch. 4.

Mercaptans or their derivatives that are necessary can be prepared from the corresponding alcohol halides, p-toluenesulfonates, methanesulfonates and the like. Suitable thiol derivatives which are readily converted to thiols include thioacetates (by saponification) and t-butyl thioethers or p-methoxybenzylthioethers (by treatment with acid or mercury(II) salts).

See also Volante, Tetrahedron Letters, 22, 3119-3122 (1981) regarding the conversion of alcohols to thiols and thiol esters using triphenylphosphone and a dialkyl azodicarboxylate in the presence of the alcohol and an appropriate thioacid.

In the case of compounds of formula XIV, the trialkylsilyl group is preferably removed prior to the hydrogenolysis to remove the acid-protecting group (PNB) to obtain a compound of formula XV. The trialkylsilyl group is removed with tetraalkylammonium fluoride in a volatile solvent such as tetrahydrofuran in a temperature range of about 15 to 40°C, preferably about 25°C.

Transfer of a compound of formula XV to a compound of formula I or II is carried out using a conventional hydrogenolysis reaction and is carried out in the usual manner for this type of transfer. Thus, a solution of a compound of formula XV is stirred or shaken in an atmosphere of hydrogen, or hydrogen mixed with an inert diluent such as nitrogen or argon, in the presence of a catalytic amount of a noble metal catalyst for hydrogenolysis, such as palladium-on -calcium carbonate or palladium-on-Celite (a diatomaceous earth) catalyst. Suitable solvents for this hydrogenolysis are lower alkanols such as methanol, ethers such as tetrahydrofuran and dioxane, low molecular weight esters such as ethyl acetate and butyl acetate, water, and mixtures of these solvents. However, it is common to choose conditions so that the starting materials are soluble. The hydrogenolysis is usually carried out at room temperature and at a pressure of from about 0.5 to about 5 kg/cm 2 . The catalyst is usually present in an amount from about 10 percent by weight based on the starting materials, up to an amount equal in weight to the starting materials, even if larger quantities can be used. The reaction usually takes about one hour, after which the compound of formula I or II is simply collected by filtration, followed by removal of the solvent in vacuo. If palladium-on-calcium carbonate is used as the catalyst, the product is often isolated as the calcium salt, and if palladium-on-Celite (a diatomaceous earth) is used, the product is often isolated as the sodium salt.

The compounds of formula I or II can be purified by usual methods for beta-lactam compounds. For example, a compound of formula I or II can be purified by column chromatography gel filtration on Sephadex, or by recrystallization.

An alternative synthetic procedure is shown in Scheme C. The azetidinone of formula IX is reacted with a trithiocarbonate of formula M<+>R-S-C(S)-S~, wherein M is a metal such as sodium or potassium, using the procedure as previously described to produce X.

The resulting trithiocarbonate XVA is treated with (p-nitrobenzyloxycarbonyl)(dihydroxy)methane in a non-protic solvent such as benzene, toluene or dimethylformamide, preferably benzene, at a temperature in the range of 25-110°C,

preferably around 80°C to give the alcohol of formula XVI.

The corresponding chloride XVII is prepared from the alcohol XVI by treatment with thionyl chloride in a reaction-inert organic solvent such as dichloromethane in the presence of a hindered amine which acts as an acid acceptor such as 2,6-lutidine in a temperature range of about -10 to 75 °C, preferably 0 °C.

The chloride XVII is reacted with a triarylphosphine such as triphenylphosphine, in a reaction-inert solvent such as tetrahydrofuran in the presence of a tertiary amine such as 2,6-lutidine at a temperature of about 25°C, to obtain the compound of formula XVIII which is cyclized by refluxing in an aromatic solvent such as toluene to give the penem of formula XIV.

The trithiocarbonate salts of formula M+R-S-(C=S)-S are prepared from the appropriate mercaptan of formula R-SH or by p treating a thioacetate of formula RSC(0)CH3 with an alkali metal alkoxide followed by carbon disulfide.

Using the aforementioned method of Yoshida et al, the stereochemistry at carbon atom 6 of the penem and also the hydroxyethyl group attached to carbon atom 6 is as shown in formula II. The essential stereochemistry of the product of ring closure when schemes B or C are used is that in which the hydrogen at penem ring position 5 is trans to the hydrogen at carbon 6 and o alpha configuration.

The compounds of formula I or II are acidic and will form salts with basic reagents. The preparation of such salts is considered to be within the scope of this invention. These salts can be prepared by standard techniques such as contacting the acidic and basic components, usually in stoichiometric ratios, in an aqueous, non-aqueous or semi-aqueous medium, as appropriate. They are then collected by filtration, by precipitation with a non-dissolving reagent followed by filtration, by evaporation of the solvent, or in the case of aqueous solutions, by lyophilization, as appropriate. Basic reagents suitably used in salt formation are of both the organic and inorganic types and include ammonia, organic amines, alkali metal hydroxides, carbonates, bicarbonates, hydrides and alkoxides, as well as alkaline earth metal hydroxides, carbonates, hydrides and alkoxides. Representative examples of such bases are primary amines such as n-propylamine, n-butylamine, aniline, cyclohexylamine, benzylamine and octylamine, secondary amines such as diethylamine, morpholine, pyrrolidine and piperidine, tertiary amines such as triethylamine, N -ethyl piperidine, N-methylmorpholine and 1,5-diazabicyclo 4,3,0 non-5-ene, hydroxides such as sodium hydroxide, potassium hydroxide, ammonium hydroxide and barium hydroxide, alkoxides such as sodium ethoxide and potassium ethoxide, hydrides such as potassium hydride and sodium hydride, carbonates such as potassium carbonate and sodium carbonate, bicarbonates such as sodium bicarbonate and potassium bicarbonate and alkali metal salts of long chain fatty acids such as sodium 2-ethyl hexanoate.

Preferred salts of the compounds of formula I or II are sodium, potassium and calcium salts.

The pharmaceutically acceptable salts of formula I or II are those which are free from significant deleterious side effects at a normal level of use, and include, e.g. sodium, potassium or potassium salts thereof.

The in vitro antibacterial action of the compounds of formula I or II and salts thereof can be demonstrated by measuring their minimum inhibitory concentrations (MIC's) in mcg/ml against a spectrum of microorganisms. The procedure followed is that recommended by the International Collaborative Study on Antibiotic Sensitivity Testing (Ericcson and Sherris, Acta. Pathologica etMicrobiologica Scandinav, Supp. 217, Section B: 6468 (1971), and uses "brain heart infusion" ( BHI) agar and equipment for repeated inoculation. Tubes grown overnight are diluted 100-fold to be used as standard inoculum (20,000-10,000 cells in approximately 0.002 ml are applied to the agar surface 20 ml BHI agar/dish). Twelve 2-fold dilutions of the test compound, with an initial concentration of the drug to be tested of 200 mcg/ml. Single colonies are omitted when the plates are read after 18 hours at 37° C. The sensitivity of the test organism (MIC) is the lowest concentration of the compound that is in capable of completely inhibiting growth, judged by the naked eye.

The compounds of formula I or II, and the pharmaceutically acceptable salts thereof, are suitable for the control of bacterial infections with susceptible bacteria in mammals, including humans, e.g. infections caused by sensitive strains of Staphylococcus aureus.

The compounds prepared according to the present invention can be administered orally or parenterally, i.e. intramuscularly, subcutaneously, intraperitoneally or intravenously, alone or together with a pharmaceutically acceptable carrier. The ratio between active ingredient and carrier depends on the active ingredient's chemical nature, solubility and stability, as well as the dosage being considered. The ratio of the pharmaceutically acceptable carrier to the penem compound will normally be in the range of about 1:10 to 4:1. For oral administration, the compounds produced according to this invention can be used in the form of tablets, capsules, lozenges of various kinds, powders, syrups, elixirs, aqueous solutions and suspensions and the like. In the case of tablets, carriers which may be used may include lactose, sodium citrate and salts of phosphoric acid. Various disintegrants such as starch and lubricants such as magnesium stearate, sodium lauryl sulfate and talc are commonly used in tablets. Useful diluents for capsules include lactose and high molecular weight polyethylene glycols. When aqueous suspensions are required for oral use, the active ingredient can be combined with emulsifying and suspending agents. Sweeteners and/or flavorings can be added. For parenteral administration, sterile solutions of the active ingredient are usually prepared, and the pH of the solution is adjusted and buffered appropriately. For intravenous use, the total concentration of dissolved substances must be controlled so that the preparation is made isotonic.

The attending physician determines the appropriate dose for a given human patient, and this may vary according to age, weight and the individual patient's response, as well as the nature and degree of symptoms. The compounds of formula I or II will normally be used orally in dosages in the range from about 10 to about 200 mg per kilo body weight per day, and parenterally in dosages from around 10 to around 400 mg per kilo body weight per day. In some cases, it may be necessary to use dosages outside these limits.

The following examples and representations are provided solely as further illustration. Infrared spectra (IR) were measured either as potassium bromide disks (KBr disk) "Nujol mulls" (Nujol) or as solutions in chloroform (CHCl 2 ), methylene chloride (CH 2 Cl 2 ) or dimethyl sulfoxide (DMSO), and diagnostic absorption bands are indicated either in microns or wavenumber (cm^).

Nuclear magnetic resonance (NMR) spectra were measured for solutions in deuterochloroform (CDCl^) or perdeuterodimethylsulfoxide (DMSO-d^), or mixtures thereof, and the positions of the peaks are indicated in parts per million (ppm) down the field from tetramethylsilane. The following abbreviations for the shape of the peaks are used: s, singlet; d, doublet;

t, triplet; q, quartet; m, multiplet; b, wide; c, complex. The abbreviations "ss" and "sss" indicate that a particular proton appears as two or three singlets, respectively, due to ac diastereoisomers. Throughout the examples and formulations, the abbreviation "PNB" means the p-nitrobenzy1 group.

EXAMPLE 1

Sodium (5R,6S)-6-(R)-1-hydroxyethyl-2-(imidazol-1-yl)-ethylthio-2-penem-3-carboxylate

A suspension of 38 mg of 10% palladium-on-diatomaceous earth in 10 ml of tetrahydrofuran and 10 ml of water was adjusted to pH 7.0 with 0.1 N aqueous hydrochloric acid solution. A solution of 38 mg of p-nitrobenzyl-(5R,6S)-6-[_(R)-1-hydroxyethylj-2-(imidazol-1-yl)ethylthio-2-penem-3-carboxylate in 5 ml of tetrahydrofuran and 5 ml of distilled water was added and the resulting mixture was hydrogenated at 3.867 kg/cm 2 of hydrogen for 75 minutes; 38 mg of 10% palladium-on-diatomaceous earth was added to the reaction mixture and the pH of the suspension was adjusted to 7.0 with 0.02M aqueous sodium bicarbonate solution. The mixture was hydrogenated at 3.867 kg/cm 2 of hydrogen for 75 minutes, then the catalyst was removed by filtration, and the filtrate was concentrated in vacuo to remove tetrahydrofuran. The pH of the resulting aqueous solution was adjusted to 7.0, and the solution was extracted with 25 ml of ethyl acetate. The aqueous layer was then lyophilized to give 23 mg (80% yield) of the title compound as an amorphous solid.

The infrared spectrum of the title compound as a potassium bromide disk had absorptions at 2.93, 5.65 and 6.28 microns.

The NMR spectrum at 250 MHZ for a perdeuterodimethylsulf- o':<£ yd solution of the title compound shows peaks at 1.16 (d, 3H); 3.2 (m, 2H); 3.54 (m, 1H); 3.92 (m, 1H); 4.18 (m, 2H); 5.54 (s, 1H); 6.88 (s, 1H); 7.2 (s, 1H) and 7.65 (s, 1H) ppm.

EXAMPLE 2

Sodium-(5R,6S)-6-(R)-1-hydroxyethyl-2-(imidazol-4-yl)-methylthio-2-penem-3-carboxylate

The method in Example 1 was applied using p-nitrobenzyl sodium-(5R,6S)-6-[(R)-1-6-alpha-hydroxyethyl]]-2-(imidazol-4-yl)methylthio-2- penem-3-carboxylate as starting material to obtain sodium-(5R,6S)-6- \_ (PJ-1-hydroxyethyl]-2-(4_imidazolylmethylthio-2-penem-3-carboxylate in 38% yield. The infrared spectrum to the product as a potassium bromide disc showed absorptions at 2.93, 5.65 and 6.26 microns.

Using the starting material p-nitrobenzyl 1-(5R, 6S)-6-[(R)-1-hydroxyethyl J-2- 1-(imidazol-1-yl)prop-2-yl thio-2-penem-3-carboxylate which is derived from the least polar diastereomer, the corresponding sodium salt of the product of formula II was obtained in 97.5% yield (IR("Nujol mull"): 5.65 microns).

Similarly, using the compound of formula XV wherein R is 1-(imidazol-1-yl)prop-2-yl derived from the most polar diastereomer as starting material, the corresponding sodium salt of the product of formula II was prepared with 60% yield (IR ("Nujol mull"): 5.66 microns).

EXAMPLE 3

Calcium-(5R,6S)-6-(R)-1-hydroxyethyl-2-(1-methylimidazol-2-yl)methylthio-2-penem-3-carboxylate

A solution of 0.12 g of p-nitrobenzyl 1-(5R_,6S)-6-£(F0 - 1-hydroxyethyl)-2-(1-methylimidazol-2-yl)methylthio-2-penem-3-carboxylate in 15 ml of tetrahydrofuran and 5 ml of water were added to a suspension of 0.12 g of 5% palladium-on-calcium carbonate in 20 ml of water and 10 ml of tetrahydrofuran which had been prehydrogenated at 3.867 kg/cm 2 hydrogen.The mixture was hydrogenated at 3.867 kg /cm<2>hydrogen for 45 minutes, then 0.12 g 5% -i i ,j;,™_„S_i/^i ^ 1 n mV =•>->-. nr, =+- fil catt orr hl anrfi napn hip hvdrogenated at 3.867 kg/cm 2 for another 60 minutes. The catalyst was removed by filtration, and the filtrate was concentrated in vacuo to remove tetrahydrofuran. The aqueous solution was washed with three 25 mL portions of ethyl acetate and then lyophilized, and it gave 74 mg (82% yield) of the title compound as an amorphous solid.

The infrared spectrum of the title compound as potassium bromide disc showed absorptions at 2.92, 5.7 and 6.28 microns.

The NMR spectrum at 250 MHZ of the title compound in per-deuterodimethylsulfoxide solution has peaks at 1.16 (d, 3H); 3.55-3.7 (m with s at 3.64, total 4H); 3.94 (m, 1H); 4.21 (q, 2H); 5.5 6 (s, 1H); 6.8 (s, 1H) and 7.1 (s, 1H) ppm.

MANUFACTURE A

p-nitrobenzy1-(5R,6S)-6-£(R)-1-hydroxyethyl]-2-(imidazol-1-y1)ethylthio-2-penem-3-carboxylate

To a solution of 152 mg (0.258 mmol) p-nitrobenzyl-(5R,6S_)-6-[(R)-1-t-butyldimethylsilyloxyethyl]-2-[(imidazol-1-yl)ethylthio 2-2-penem -3-carboxylate in 7 ml of tetrahydrofuran, 0.15 ml (2.58 mmol) of acetic acid and 0.774 ml (0.774 mmol) of an IM solution of tetrabutylammonium fluoride in tetrahydrofuran were added. After stirring for 24 hours under nitrogen at room temperature, 50 ml of ethyl acetate was added and the resulting solution was washed with 30 ml of saturated aqueous sodium bicarbonate solution, 30 ml of water and 30 ml of saturated aqueous sodium chloride solution. The ethyl acetate layer was dried over anhydrous sodium sulfate and concentrated in vacuo. The crude product was purified by column chromatography on silica gel (50 g), eluted with 85:15 ethyl acetate-methanol, and gave 77 mg (63% yield) of the title compound as an amorphous solid.

The infrared spectrum of a dichloromethane solution of the title compound showed absorptions at 5.57, 5.92 and 6.58 microns.

The NMR spectrum of a deuterochloroform solution of the title compound showed peaks at 1.34 (d, 3H); 2.76-3.38 (c, 2H); 3.72 (m, 1H); 4.24 (m, 3H); 5.28 (q, 2H); 5.62 (d, 1H); 6.93 (m, 2H); 7.5 (d, 3H) and 8.13 (d, 2H) ppm.

MANUFACTURE B

The procedure in Preparation A was used to prepare the compound of formula XV, where R and the physical data are as shown in Table I, from the corresponding compound of formula XIV. The solvents are shown in parentheses.

MANUFACTURE C

p- nitrobenzyl-(5R6S)-6-(R)-1-t-butyldimethylsiloxyethyl-2-((imidazol-1-yl)ethylthio)-2-penem-3-carboxylate

Sodium methoxide (228 mg, 4.22 mmol) was added to a solution of 715 mg (4.22 mmol) of 2-(imidazolyl)ethylthioacetate in 35 ml of anhydrous ethanol which had been cooled to -35°C under nitrogen after 65 min. at -35°C, a solution of 2.5 g (ca. 4.22 mmol) of impure p-nitrobenzy1-(5R,6S)-6- (R)-1-t-butyldimethylsilyloxyethyl]- 2-ethylsulfinyl-2-penem-3-carboxylate in 35 ml of tetrahydrofuran, which had been cooled to -50°C, was added. The resulting solution was stirred at -35°C to -40°C for 75 min, and then 0.24 ml (4.22 mmol) of acetic acid was added and the solution was concentrated in vacuo. The residue was dissolved in 150 ml of ethyl acetate and the resulting solution was

washed with 75 ml saturated aqueous sodium bicarbonate solution,

75 ml of water and 75 ml of saturated sodium chloride solution. The ethyl acetate layer was dried over anhydrous sodium sulfate and concentrated in vacuo. Chromatography of the crude product (3.08

g) on silica gel (500 g) and eluting with 90:10 ethyl acetate-methanol gave 980 mg (39%) of the title compound as a viscous

rubber.

The IR spectrum of the title compound in dichloromethane showed absorptions at 5.58, 5.92 and 6.57 microns.

The NMR spectrum of a deuterochloroform solution of the title compound showed peaks at 0.3 (s, 3H) , 0.08 (s, 3H), 0.8 (s, 9H9, 1.23 (d, 3H) , 2, 75-3.4 (c, 2H), 3.72 (m, 1H), 4.28 (m, 3H), 5.3 (q, 2H), 5.66 (d, 1H), 7.0 (m, 2H), 7.6 (d, 3H) and 8.2 (d, 2H) ppm.

MANUFACTURE D

p-nitrobenzyl-(5R,6S)-6-(R)-1-t-butyldimethylsiloxyethyl -2-(imidazol-4-y1)methylthio-2-penem-3-carboxylate

The procedure of Preparation C was used using imidazol-4-ylmethylthioacetate as the thioacetate to prepare the title compound in 15% yield.

The IR spectrum of a dichloromethane solution of the title compound showed absorptions at 5.58, 5.92 and 6.57 microns.

The NMR spectrum of a deuterochloroform solution of the title compound showed peaks at 0.02 (s, 3H), 0.06 (s, 3H), 0.8 (s, 9H), 1.22 (d, 3H), 3.66 (m, 1H), 4.2 (c, 3H), 5.24 (q, 2H), 5.6 (d, 1H), 6.97 (s, 1H), 7.4 (d ) and 7.57 (s)

(total 3H) and 8.18 (d, 2H9 ppm.

MANUFACTURE E

p- nitrobenzyl-( 5R, 6S) - 6- ]_{ R) - l- butyldimethylsiloxyethyl]]- 2-( l- methylimidazol-2-y1)methylthio-2-penem-3- carboxylate

The procedures of Preparation C were used using sodium ethoxide in place of sodium methoxide and using 1-methylimidazol-2-ylmethylthioacetate as the thioacetate to prepare the title compound in 44% yield.

The IR spectrum of a "Nujol mull" of the title compound showed absorptions at 5.58 and 5.9 microns.

The NMR spectrum of a deuterochloroform solution of the title compound showed peaks at 0.03 (s, 3H), 0.06 (s, 3H), 0.84 (s, 9H), 1.24 (d, 3H), 3.56-3.8 (st with s at 3.7, total 4H), 3.95-4, 44 (st with s at 4.3, total 3H), 5.24 (q, 2H), 5 .64 (d, 1H), 6.8 (d, 1H), 6.9 (d, 1H), 7.5 (d, 2H) and 8.1 (d, 2H).

MANUFACTURE F

p-nitrobenzyl-(5R,6S)-6-(R)-1-t-butyldimethylsiloxyethyl-2-ethylsulfinyl-2-penem-3-carboxylate

A solution of 970 mg (4.78 mmol, 85% purity) of m-chloro-perbenzoic acid in 25 ml of methylene chloride was added to a solution of 2.5 g (4.78 mmol) of p-nitrobenzyl-(5R,6S )-6-£(R)-1-t-butyldimethylsilyloxyethyl]-2-ethylthio-2-penem-3-carboxylate in 125 ml of methylene chloride cooled to -20°C under a nitrogen atmosphere. The mixture was stirred at -20°C for 3 hours, then washed successively with two 70 mL portions of saturated aqueous sodium bicarbonate solution, 70 mL water, and 70 mL saturated aqueous sodium chloride solution. The methylene chloride solution was dried with anhydrous sodium sulfate and concentrated in vacuo to a yellow foam of the title compound (2.2 g, 86% yield).

The infrared spectrum of the title compound in dichloromethane solution showed absorptions at 5.54, 5.86 and 6.53 microns.

The NMR spectrum of the title compound as deuterochloroform solution had peaks at 0.06, 0.08, 0.1 and 0.12 (4s, total 6H), 0.8 (s, 9H), 1.12-1, 58 (m, 6H), 3.1 (m, 2H), 3.86 (m, 1H), 4.3 (m, 1H), 5.3 (m, 2H), 5.67 and 5.78 (2d, total 1H), 7.54 (d, 2H) and 8.18 (d, 2H) ppm.

MANUFACTURE G

p-nitrobenzyl-(5R,6S)-6-[_(R)-1-t-butyldimethylsilyloxyethyl]-2-ethylthio-2-penem-3-carboxylate

p-nitrobenzy1-oxalyl chloride (5.85 g, 0.024 mol) was added to a mixture of 7.3 g (0.02 mol) of (5R,6S)-6-[(R)-1-t-butyldimethylsilyloxyethyl]- 4-ethylthio(thiocarbonyl)thio-2-oxo-azetidine and 4.8 g (0.048 mol) of calcium carbonate in 70 ml of methylene chloride cooled to 10~C under a nitrogen atmosphere. A solution of 4.17 ml (0.024 mol) of diisopropylethylamine in 20 ml of methylene chloride was added dropwise at a rate which kept the temperature below 12°C. The mixture was stirred for 60 min. at 10°C, then washed with two 50 ml portions of ice-cold water, dried over anhydrous sodium sulfate and concentrated in vacuo to a viscous oil. The resulting crude p-nitrobenzyl-(3-alpha-(R)-t-butyldimethylsilyloxyethyl1-2-oxo-azetidinyl)oxoacetate was dissolved in 300 ml of ethanol-free chloroform and the resulting solution was heated at reflux under nitrogen, while a solution of 6.85 ml (0.04 mol) triethyl phosphate in 50 ml ethanol-free chloroform was added dropwise over 16 hours, then concentrated in vacuo. The residue was chromatographed on silica gel (800 g), eluting with 95:5 toluene-ethyl acetate, to give 5.5 g (53% yield) of the title compound as a yellow foam.

The infrared spectrum of the title compound as a dichloromethane solution showed absorptions at 5.56, 5.89 and 6.54 microns.

The NMR spectrum of the title compound as a deuterochloroform solution showed peaks at 0.07 (s, 3H), 0.1 (s, 3H), 0.85 (s, 9H), 1.12-1.53 (m, 6H ), 2.97 (q, 2H), 3.7 (m, 1H), 4.25 (m, 1H), 5.3 (q, 2H), 5.63 (d, 1H), 7.38 (d, 2H) and 8.18 (d, 2H) ppm.

The NMR spectrum of the intermediate, 4-ethylthio(thiocarbonyl)-thio-azetidinone in the deuterochloroform solution showed peaks at 0.06 (s, 6H), 0.8 (s, 9H), 1.14-1.62 (m , 6H) , 3.14-3.63 (m, 3H), 4.33 (m, 1H), 5.16 (s, 2H), 6.7 (d, 1H), 7.5 (d, 2H) and 8.17 (d, 2H) ppm.

MANUFACTURE H

3- alpha-(R)- t- butyldimethyl silyloxyethyl- 4- ethylthio(thiocarbonyl)-thio- 2- oxo- azetidine

Ethanethiol (8.5 mL, 0.115 mol) was added to a solution of 4.18 g (0.104 mol) of sodium hydroxide in 250 mL of water cooled to 0-5°C under a nitrogen atmosphere. After 15 min. 7.73 ml (0.12 mol) of carbon disulfide was added and the mixture was stirred at 0-5°C for 35 min. A solution of 15.0 g (0.0522 mol) of 4-acetoxy-3-t-butyldimethylsilyloxyethyl-2-aztidinone in 500 ml of methylene chloride was added and the mixture was stirred vigorously at room temperature for 24 hours. The aqueous phase was separated and extracted with two 15 ml portions of methylene chloride. The combined methylene chloride fractions were washed with two 200 mL portions of water and 200 mL of saturated aqueous sodium chloride solution, dried over anhydrous sodium sulfate, and concentrated in vacuo. The crude title product (18 g) was chromatographed on silica gel (500 g), eluted with 99:1 chloroform-ethyl acetate, to give 9.1 g (48% yield) of the title trithiocarbonate as a yellow foam.

The infrared spectrum of the title compound in the dichloromethane solution showed absorptions at 5.62 and 9.2 microns.

The NMR spectrum of a deuterochloroform solution of the title compound showed peaks at 0.08 (s, 6H), 0.8 (s, 9H), 1.02-1.5 (m, 6H), 3.0-3, 48 (m, 3H), 4.12 (m, 1H), 5.54 (d, 1H) and 6.57 (b, 1H) ppm.

MANUFACTURE I

2-(imidazol-1-yl) ethyl thioacetate

A mixture of 4.0 g (0.015 mol) of 2-(imidazol-1-yl)ethyl tosylate and 2.6 g (0.0225 mol) of potassium thioacetate in 100 ml of acetone was refluxed under nitrogen overnight. The reaction mixture was then filtered and the filtrate was concentrated in vacuo. The residue was dissolved in 100 ml of ethyl acetate and 100 ml of water and the ethyl acetate layer was washed with 100 ml of water and 100 ml of saturated aqueous sodium chloride solution, dried over anhydrous sodium sulfate and concentrated in vacuo. The crude product was chromatographed on silica gel, eluting with 9:1 ethyl acetate-methanol, to give 1.0 g (39% yield) of the title thioacetate as a yellowish oil.

The NMR spectrum of a deuterochloroform solution of the title compound showed peaks at 2.36 (s, 3H), 3.17 (t, 2H), 4.08 (t, 2H), 6.9 (d, 1H), 6.98 (d, 1H) and 7.47 (s, 1H) ppm.

MANUFACTURE J

2-(imidazol-1-yl)ethyl tosylate

A solution of 2.24 g (0.02 mol) 2-(imidazol-1-yl)ethanol and 4.88 g (0.04 mol) 4-dimethylaminepyridine in 100 ml methylene chloride was cooled to 0°C under nitrogen and 3.8 g (0.02 mol) of p-toluenesulfonyl chloride was added. The resulting solution was stirred at 0°C for 3 hours, then at room temperature overnight. 100 ml of water was added and the pH of the mixture was adjusted to 7.0 with 1N aqueous hydrochloric acid solution. The methylene chloride layer was separated, washed with 70 mL saturated aqueous sodium chloride solution, dried over anhydrous sodium sulfate and concentrated in vacuo to an oil (4.2 g) of the title compound.

The NMR spectrum of a deuterochloroform solution of the title compound showed peaks at 2.42 (s, 3H), 4.23 (s, 4H), 6.86 (d, 1H), 7.0 (d, 1H) and 7.16-7.8 (m, 5H) ppm.

MANUFACTURE K

Imidazol-4-ylmethylthioacetate

To a solution of 890 mg (7.8 mmol) of potassium thioacetate in 30 ml of ethanol was added 800 mg (5.2 mmol) of 4-(chloromethyl)-imidazole hydrochloride. The resulting solution was stirred overnight at room temperature under nitrogen. The reaction mixture was then concentrated to dryness in vacuo. 100 ml of ethyl acetate and 100 ml of saturated aqueous sodium bicarbonate solution were added to the residue. The ethyl acetate layer was separated and washed in turn with 70 ml of saturated aqueous sodium bicarbonate solution, 70 ml of water and 70 ml of saturated aqueous sodium chloride solution, dried over anhydrous sodium sulfate and concentrated in vacuo. The crude product was chromatographed on silica gel (150 g), eluting with 9:1 ethyl acetate/methanol to give 300 mg (37%) of the title thioacetate as a yellowish oil.

The NMR spectrum of a deuterochloroform solution of the title compound had peaks at 2.32 (s, 3H), 4.14 (s, 2H), 6.99 (s, 1H) and 7.64 (s, 1H) ppm.

MANUFACTURE L

(1-methylimidazol-2-yl)methylthioacetate

A solution of 1.0 g (0.0089 mol) (1-methylimidazol-2-yl)methanol, 4.7 ml carbon tetrachloride and 2.93 g (0.011 mol) triphenylphosphine in 35 ml chloroform was heated at reflux under nitrogen in 2 hours. The reaction mixture was then cooled to 25°C and 2.8 g (0.0089 mol) of tetrabutylammonium thioacetate was added and the resulting solution was stirred at room temperature overnight. The entire reaction mixture was loaded onto a silica gel column (200 g). Elution with 2:1 methylene chloride-acetone gave 600 mg of product contaminated with an impurity which was removed by repeated column chromatography on silica gel (200 g). Elution with 4:1 methylene chloride-acetone gave 0.3 g (20% yield) of the title thioacetate as a yellowish oil.

The NMR spectrum of a deuterochloroform solution of the title compound had peaks at 2.37 (s, 3H), 3.58 (s, 3H), 4.18 (s, 2H), 6.72 (d, 1H) and 6.81 (d, 1H) ppm.

MANUFACTURE M

p- nitrobenzyl-(5R,6S)-6-[_(R)-1-t-butyldimethylsiloxyethyl]-2-(1-imidazol-1-yl)prop-2-yl)thio-2-penem- 3- carboxylate

Sodium methoxide (36.5 mg, 0.68 mmol) was added to a solution of (2-(methylcarbonylthio)propyl)imidazole (130 mg, 0.71 mmol) in 7 mL of anhydrous ethanol that had been cooled to -35°C under nitrogen . The resulting solution was stirred

-25°C for 1 hour and then cooled to -40°C.

A solution of p-nitrobenzyl-(5R,6S)-6-£(£.)-1-t-butyl-dimethylsilyloxyethyl]-2-ethylsulfinyl-2-penem-3-carboxylate in 7 ml of anhydrous tetrahydrofuran which had been cooled to -50°C, was added and the resulting solution was stirred at -40°C for 50 min. Acetic acid (0.68 mmol) was added and the solution was concentrated in vacuo. The residue was redissolved in ethyl acetate (40 ml) and the resulting solution was washed with 30 ml of aqueous sodium bicarbonate solution, 30 ml of water and 30 ml of saturated aqueous sodium chloride solution. The ethyl acetate solution was then dried over anhydrous sodium sulfate and chromatographed on silica gel (150 g), eluting with 95:5 ethyl acetate-methanol to give 72 mg (18.5% yield) of the less polar stereoisomer, 124 mg ( 31% yield) of a mixture of diastereomers and 72 mg (18.5% yield) of the most polar diastereomer.

less polar diastereomers

IR(CH 2 Cl 2 ): 5.57, 5.88 and 6.54 microns.

NMR(CDCl 3 ): 0.04 (s, 3H), 0.06 (s, 3H), 0.82 (s, 9H), 1.23 (d, 3H), 1.3 (d, 3H), 3 , 37-4, 46 (c, 5H) , 5.25 (q, 2H) , 5.56 (d, 1H), 6.86 (m, 1H), 6.98 (m, 1H), 7 .42 (m, 1H), 7.54 (d, 2H) and 8.12 (d, 2H) ppm.

most polar diastereomers

IR(CH 2 Cl 2 ): 5.58, 5.92 and 6.58 microns.

NMR(CDCl 3 ): 0.05 (s, 3H), 0.08 (s, 3H), 0.83 (s, 9H), 1.26 (d, 3H), 1.32 (d, 3H), 3, 36-4, 47 (c, 5H) , 5.24 (q, 2H) , 5.58 (d, 1H), 6.86 (m, 1H) , 6.97 (m, 1H), 7 .4 (m, 1H), 7.5 (d, 2H) and 8.1 (d, 2H) ppm.

PRODUCTION N

(2-methylcarbonylthio)propyl)imidazole

A solution of 500 mg (1.8 mmol) of (2-(p-methylphenylsulfonyloxy)propyl)imidazole and 1.4 g (3.6 mmol) of tetrabutylammonium thioacetate in 30 mL of acetone was refluxed under nitrogen overnight . The reaction mixture was concentrated to dryness in vacuo and the residue was dissolved in 40 ml of ethyl acetate. The ethyl acetate solution was washed with 40 ml of water, 40 ml of saturated aqueous sodium chloride solution, 40 ml of water and 40 ml of saturated sodium chloride solution, dried over anhydrous sodium sulfate and concentrated in vacuo. The crude product was purified by column chromatography on silica gel (80 g), washed out with 95:5 ethyl acetate-methanol, and gave 160 mg of the title compound (48% yield).

NMR(CDCl 3 ): 1.22 (d, 3H), 2.32 (s, 3H), 3.56-4.27 (c, 3H), 6.95 (m, 1H), 7.0 (m , 1H) and 7.44 (m, 1H) ppm.

MANUFACTURE 0

(2-(p-methylphenylsulfonyloxy)propyl)imidazole

p-toluenesulfonyl chloride (1.9 g, 0.01 mol) was added portionwise to a solution of 1-(1-imidazole)-2-propanol (1.26 g, 0.01 mol) and 4-dimethylaminopyridine (2, 44 g, 0.02 mol) in 60 ml of methylene chloride which had been cooled to 0°C under nitrogen. The solution was stirred at 0°C for 30 min, then at 25°C overnight. Water, (60 mL) was added and the pH of the resulting mixture was adjusted to 7.0 with 1N aqueous hydrochloric acid solution. The methylene chloride solution was separated, washed with 50 ml saturated aqueous sodium chloride solution, dried over anhydrous sodium sulfate and concentrated to dryness in vacuo. The crude product was purified by column chromatography on silica gel (200 g), eluting with 9:1 ethyl acetate-methanol to give 1.5 g (54% yield) of the title compound.

NMR(CDCl 3 ): 1.27 (d, 3H), 2.42 (s, 3H), 3.97-4.2 (c, 3H), 4.77 (m, 1H), 6.75 (m , 1H), 7.15 (m, 1H), 6.9 (m, 1H), 7.2 (d, 2H) and 7.6 (d, 2H) ppm.

MANUFACTURE P

(2-Hydroxypropyl)imidazole

A mixture of 27.8 g (0.41 mol) of imidazole and 41.2 ml (0.48 mol) of propylene carbonate in 70 ml of toluene was refluxed under a nitrogen atmosphere for 5 hours. The reaction mixture was cooled and the lowest product layer was separated from the toluene layer and purified by vacuum distillation. 43.5 g (84% yield) of the product appeared as a colorless liquid,

cooking time 145-148°C (1.8mm).

Claims (4)

1. Process for preparing a compound of formula or or a pharmaceutically acceptable salt thereof, wherein R is -(alk)-X-R 1 X is imidazole, 1,2,3-triazolyl, 1,2,4-triazolyl or tetrazolyl; R 1 is hydrogen or alkyl having 1-4 carbon atoms; R 1 is hydrogen or a group that forms an ester that is hydrolyzed in vivo; and alk is the alkylene having 1-4 carbon atoms; characterized by the step that a compound of formula I or II, respectively, where R^ is a carboxylic acid protecting group, is hydrogenated. 2. Process according to claim 1, characterized in that a compound is prepared where R2 is hydrogen and R is 1-(imidazol-1-yl)prop-2-yl or (imidazol-4-yl)methyl. 3. Method according to claim 1, characterized in that a compound is prepared where R 1 is hydrogen and R is 2-(imidazol-1-yl)ethyl. 4. Process according to claim 1, characterized in that a compound is prepared where R2 is hydrogen and R is (1-methylimidazol-2-yl) methyl.