DE1768047C3 - Dimethoxybenthydryl asparagine and glutamine derivatives and processes for the production of asparagine and glutamine-containing peptides - Google Patents

Description

(CH ₂ ),

I. co

NH

H ₁ CO

(II) or (Ha)

OCH ₃

CO

NH ₂

in which G is an acyl radical which is acid-stable under the conditions of preparation or a hydrogen atom, A and B are identical or different amino acid radicals or peptide fragments and R is an alkyl, aralkyl or aryl radical or a hydrogen atom, χ and y represent the number O or an integer and π stand for the numbers 1 and 2, with 4,4'-dimethoxybenzhydrol in glacial acetic acid in the presence of acidic catalysts to form compounds

20th

25th

where G, A, B, R, x, y and η have the abovementioned meaning, converts these derivatives into other derivatives of the general formula (Ha) according to the general methods of peptide chemistry, where (Ha) with respect to A and / or B and / or χ or y differs from the compounds of the formula II and optionally then splits off the 4,4'-dimethosybenzhydryl group by allowing strong organic acids or mineral acids to act

2. Dimethoxybenzhydryl aspaiagin and glutamine derivatives of the general formula

CH ₃ O

CH ₃ O

NHR ¹ CH-NH-CO- (CH ₂ ), -CH-COOR

in which η denotes the numbers 1 or 2, R ^{denotes hydrogen or the methyl group and R 1} denotes hydrogen or the carbobenzoxy radical, where, if R ¹ denotes hydrogen and R denotes the methyl group, the compounds are in the form of their salts with strong acids.

In the synthesis of asparagine- and glutamine-containing peptides, in which the amide functions are not are protected, numerous side reactions occur. With asparagine as well as with glutamine peptides the amide function can be dehydrated to the nitrile group by peptide-forming reagents, by intermediate Occurring cyclic imides can be isoasparagine or isoglutamine derivatives and by acidic such as Basic hydrolysis can also split the amide function (cf.Echröderu. K.Lübke, The Peptides, Vol. I, Academic Press, New York and London, 1965, pp. 110, 203-204 and 191). In the case of N-terminal glutamine peptides, pyroglutamic acid formation also plays a role (cf. Liebigs Ann. Chem., 707, 232 [1967]). In order to avoid these side reactions, protective groups for the Amide functions developed.

So was z. B. by reacting N-carbobenzoxy-L-glutamine with xanthydrol in glacial acetic acid N * -Carbobenzoxy-Nr-xanthyl-L-glutamine obtained. The xanthy group can be reassembled with HBr in glacial acetic acid split off. But the yield after the cleavage is low. Another disadvantage is the poor solubility the xanthyl compounds (cf. Bull. Chem. Soc. Jap, 35, 1966 [1962]).

Made from N-protected glutamic acid and asparagine

Acid a-benzyl esters was obtained by reaction with bis- (2,4-dimethoxybenzylamine) according to the ynamine method the corresponding <a- [bis- (2,4-dimethoxybenzyl)] - amide produced (cf. Tetrahedron Letters [London], 1966, p. 3483). This protective group can be split off by standing in trifluoroacetic acid / anisole for a long time. The disadvantage of this method is the uneconomical and laborious production of the amide protected asparagine and glutamine derivatives.

No'-carbobenzoxy-Ni'-benzhydryl-L-glutamine was produced by the same complex process (see Bull. Chem. Soc. Jap, 40, 2164 [1967]). These Protecting group is in anhydrous hydrogen fluoride cleaved.

In the search for more suitable amide protective groups, it has now surprisingly been found that 4,4'-dimethoxybeathydrol with asparagine or glutamine, as well as with N-carbobenzoxy-aspara gin or N-carbobenzoxy-glutamine in glacial acetic acid Proton catalysis converts to the corresponding 4,4'-dimethoxybenzhydrylamides. The 4,4'-dimethoxybenzhydryl radical can easily be split off again under acidic conditions.

The invention relates to a process for the production of asparagine- and glutamine-containing Peptides, which is characterized in that asparagine and glutamine or their acid-stable Derivatives of the general formula (I)

bO

G- (A) ₁ -NH-CH-CO- (BL-OR

(CH ₂ ), (I)

CO

NH ₂ in the G one under the conditions of manufacture

acid-stable acyl radical or a hydrogen atom, A and B are identical or different amino acid radicals or peptide fragments and R is an alkyl, aralkyl or aryl radical or a hydrogen atom, xundy stands for the number 0 or an integer and π for the numbers 1 and 2, with 4,4'-Dimethoxybenzhydrol in glacial acetic acid in the presence of acidic catalysts to the compounds of the general formula (II)

G- (A) _x -NH-CH-CO- (B) _y -OR

(CH ₂ ),

(II) or (Ha)

IO

15th

20th

where G, A, B, R, x, y and π have the abovementioned meaning, converts these derivatives into other derivatives of the general formula (Ha) according to the general methods of peptide chemistry, where (Ha) with respect to A and / or B and / or χ or y differs from the compounds of the formula II, converted and, if appropriate, subsequently splitting off the 4,4'-dimethoxybenzhydryl group by allowing strong organic acids or mineral acids to act

The amide-substituted ones required for the production of the asparagine and glutamine peptides of the formula (I) Asparagine and glutamine derivatives of the formula (II) can either

1) from the N-Carbobenzoxyvert indungen of glutamine and asparagine by reacting with 4,4'-dimethoxybenzhydrol in glacial acetic acid as a solvent with the addition of acidic catalysts such as conc. Sulfuric acid, BF3 diethyl etherate, ZnCl ₂ or AlCl ₃ or organic sulfonic acids such as toluenesulfonic acid in catalytic amounts, or

2) from glutamine or asparagine by reaction with 4,4'-dimethoxybenzhydrol in glacial acetic acid as a solvent with the addition of conc. Sulfuric acid or BF ₃ diethyl etherate can be produced in molar quantities.

In addition, the 4,4'Dimethoxybenzhydrylreste can also be subsequently converted into asparagine and Introduce glutamine-containing peptides. so

These compounds can now be used according to the general methods of peptide chemistry to produce the asparagine- and giutamine-containing peptides. So z. B. from the N-carbobenzoxy compounds prepared according to method 1, the activated esters, such as p-nitrophenyl esters, in a known manner. Diazomethane produces the corresponding methyl esters, which can be converted into the methyl ester hydrochloride by hydrogenation in glacial acetic acid / methanol and subsequent titration with methanolic hydrochloric acid. For example, the N-phthalyl and N- (o-nitrosulfenyl) compounds can be ^{prepared from the Ν ω} -4,4'- dimethoxybenzhydryl asparagine and glutamine prepared according to method 2.

From these compounds can in the usual way, for. B. by the method of mixed anhydrides, the activated ester or the carbodiimide and ynamine Method peptides are produced from which according to Release of a carboxyl group, e.g. B. by saponifying an ester or releasing an amino group, higher peptides can be built up.

The choice of the other protective groups used in the peptide synthesis depends on their differentiability from the new ones according to the invention used amide protecting groups.

The new protective groups are stable to alkaline saponification, ammonolysis or hydraziolysis, so that z. B. in their presence carboxylic acid esters are converted into carboxylic acids, carboxamides or hydrazides and N-phthalyl groups can be split off. Also against other nucleophilic reagents used for Cleavage of the N- (o-nitrosulfenyl) group are used the new protective groups resistant: The o-nitrosulfenyl residue can be selectively split off under mild reaction conditions with or without the addition of indole by means of methanolic hydrochloric acid. Against catalytic The new protective groups are also stable when hydrogenated. So the N-carbobenzoxy group can selectively be dehydrated.

As further building blocks of the peptides containing the asparagine and glutamine derivatives of the general formula (II), all amino acids found in naturally occurring peptides in their L or D form are possible for A and B. The use of 0-amino acids, such as. B. ß- alanine or other only synthetically or semi-synthetically accessible amino acids, z. B. «x-methylalanine, <x-methyl-3,4-dioxy-L-phenylalanine or 0-chioralanine is possible. Further functional groups of the amino acids can or must be protected according to the rules customary in peptide chemistry (see E. Schröder and K. Lübke, The Peptides, New York and London 1965, Vol. I, especially pages 3-75) . The acid-stable acyl radical is the carbobenzoxy, phthalyl, trifluoroacetyl, tosyl and benzoyl group or a proton.

The cleavage of the new protective group succeeds according to the invention by treatment with strong organic acids such as formic acid and halocarboxylic acids of the type of trifluoroacetic acid, difluorochloroacetic acid or trichloroacetic acid, which at the same time as Solvents can serve, furthermore with preferably anhydrous mineral acids such as HBr in glacial acetic acid, anhydrous hydrogen fluoride, or with organic sulfonic acids in formic acid as a solvent. the Cleavage can be carried out at room temperature or higher temperatures. Additives that Can trap the resulting cation, such as anisole, phenols, indole or indole derivatives accelerate the Spin-off.

Table 1 gives the spin-off conditions and the Cleavage times again obtained with N-'M ^ '- dimethoxybenzhydryl-L-glutamine.

Table 1

Cleavage of the amide protecting group from N ^w -4,4'-dimethoxybenzhydryl-L-glutamine under various conditions. (The cleavage time was determined by paper chromatography).

Spin-off medium Spin-off time

1) boiling trifluoroacetic acid 15 minutes

2) boiling trifluoroacetic acid / <5 minutes Anisole

continuation

Rubbing medium

Spin-off time

15th

3) trifluoroacetic acid / aniso! at 2-3 hours Room temperature

4) Half Concentrated H3 / Ice - 1-2 hours vinegar at room temperature

5) semi-conc. HBr / glacial acetic acid / indole 5-10 minutes in at room temperature

6) Glacial acetic acid / BFj diethyl etherate 2 hours at room temperature

7) Formic acid / anisole at 80 ° for 1 hour

8) Formic acid / toluenesulfone- <5 minutes acid (4: 1) anisole at 80 °

9) Trichloroacetic acid / anisole at <5 minutes 100 °

10) trichloroacetic acid / anisole at 10-15 minutes 70 °

The products of the process can be used as intermediates, with the protective group also on the peptides can be left for the production of other therapeutically valuable glutamine or asparagine containing Peptides such as oxytocin, vasopressin, glucagon, secretin or insulin can be used.

The invention is explained in more detail by the following examples

example 1 Manufacture of L-Tyrosyl-L-glutamine

a) N - < ^e -4,4'-dimethoxybenzhydryl-L-glutamine

λ) 1.45 g (40 mmol) of glutamine and 2.4 g of 4,4'-dimethoxybenzhydrol (10 mmol) are added to 50 ml of glacial acetic acid. To do this, 034 m of conc. Sulfuric acid and stir for about 2 hours. Then 2 g of anhydrous sodium acetate are added and the mixture is concentrated. The residue is distributed between sodium acetate solution and ethyl acetate. Overnight, a precipitate falls in the refrigerator and is filtered off with suction and washed with water. Yield 1.145g (31% of theory), melting point 205-206 °. [<χ] Ό '+ 7J5 ° (c = 2 in glacial acetic acid).

ß) The connection can also be obtained as follows: _χ

5.1 g (10 mmol) of N-carbobenzoxy-N ^M -4,4'-dimethoxybenzhydryl-L-glutamine (prepared according to b) are dissolved in a mixture of glacial acetic acid and methanol (1: 1). To do this, a palladium catalyst is added and hydrogen is introduced until no more CO2 escapes. The catalyst is filtered off with suction and the filtrate is concentrated. The residue is triturated with ether and dried. Yield 3.65 g (98% of theory). After recrystallization from such water: Yield 2.81 g (75.5% of theory), melting point 205-206 °.

b) N-carbobenzoxy-N ^ra -4,4'-dimethoxybenzhydryl-L-glutamine

28 g of carbobenzoxy-L-glutamine (0.1 mol) and 24 g of 4,4'-diirethoxybenzhydrol (0.1 mol) are dissolved in 250 ml of glacial acetic acid. In addition one gives 0.5 ml of concentrated sulfuric acid at room temperature. It is left to stand overnight and then pour into 750 ml of water. An oil separates out, which soon crystallizes. The crystal pulp is filtered off with suction and dissolved in ethyl acetate Dissolved warm The ethyl acetate solution is extracted with water with sodium sulfate dried and concentrated. The residue is triturated with ether and filtered off with suction Yield 45.8 g (90% of theory), melting point 117-120 ° [«]" -6.75 (c = 2, in dimethylformamide).

ß) Other manufacturing method: According to the usual method of carbobenzoxylation, N'M ^ '- dimethoxybenzhydryl-L-glutamine is obtained in 80% yield

N-carbobenzoxy-NM ^ '- dimethoxybenzhydryl-L-glutamine. F 117-120 °.

c) N-carbobenzoxy-N'M ^ '- dir.t thoxybenzhydryl-L-glutamine methyl ester

5.1 g of N-carbobenzoxy-N ^m -4,4'-dimethoxybenzhydryl-L-glutamine are dissolved in tetrahydrofuran At room temperature, ethereal diazosiethanene solution is added dropwise until it remains yellow. Excess diazomethane is destroyed with a few drops of glacial acetic acid. The solvent is removed in vacuo and the residue triturated with petroleum ether. Yield 5.2 g (100% of theory), melting point 146-150 ° - 10.8 ° (c = 2 in dimethylformamide).

d) N - "M / 1'-dimethoxybenzhydryl-L-glutamine methyl ester hydrochloride

23 g of N-carbobenzoxy-N "-4,4'-dimethoxybenzhydryl-L-glutamine methyl ester are dissolved in a mixture of glacial acetic acid / methanol (1: 1) and hydrogenated with a Pd catalyst. After the evolution of COr has ended, the catalyst is filtered off and the solution titrated against thymol blue with methanolic hydrochloric acid, the solvent mixture is distilled off in vacuo, the residue is dissolved in methanol and _{chromatographed on a neutral Al 2} O ₃ column, yield 11.8 g (70% of theory) recrystallisable from methanol / ether, F 182 -183 ° [ä]? + 21.4 ° (c = 2, in methanol).

e) N-carbobenzoxy-O-tert-butyl-L-tyrosyl-N ^m -4,4'-dimethoxybenzhydryI-L-glutamine-methylester 1

5.6 g N-carbobenzoxy-O-tert-butyl-L-tyrosine »Jicyclohexylamine salt are released into the free by stirring at -0 ° with 2N citric acid and ethyl acetate Acid transferred. The ethyl acetate residue is dissolved in 40 ml of methylene chloride. 4.2 g are added

N - <"- 4,4'-Dimethoxybenzhydryl-L-glutamine methyl ester hydrofochloride, cools to -10 ° and gives off 1.4 ml of triethylamine to. The mixture is stirred for 10 minutes and a solution of 2.2 g of dicyclohexylcarbodiimide in a little methylene chloride is added. May. stir now a few more hours at 0 ", put the mixture in the refrigerator overnight and distilled the next day the methylene chloride from. The residue is stirred with dimethylformamide, insoluble matter is filtered off with suction and the filtrate is concentrated in vacuo. The residue is washed with methanol boiled, cooled and vacuumed. Yield 5.9g

(80% of theory) F 181-183 °. After recrystallization from methanol: mp 190-192 ° [λ] -12.1 ° (c = 2, in Dimethylformamide).

f) O-tert-butyl-L-tyrosyl-N ^M -4,4'-dimethoxybenzhydryl-L-glutamine

6 g of N-carbobenzoxy-0-tert-butyl-L-tyroxyl-N - "'- 4,4'-dimethoxybenzhydryl-L-glutamine methyl ester are suspended in about 40 ml of dioxane. 8.1 ml of 1 η are added NaOH and stir for about 2 hours at room temperature. It is neutralized with a few drops of 2 η citric acid and concentrated. The residue is partitioned between ethyl acetate and 2 η citric acid. The ethyl acetate phase is extracted once with water, dried with sodium sulfate and The residue is concentrated in glacial acetic acid / methanol (i: i) gciuSi üi'id Jiäiäiyiisüii hyui'ieii.Nuchucin, the hydrogenation is complete, the catalyst is filtered off, the filtrate is concentrated in vacuo and the residue is stirred with ethyl acetate and Yield 4.6 g (95% of theory). Can be recrystallized from 70% alcohol. It crystallizes out as a hemihydrate. Mp 174-177 ° [λ] +19.85 (c = 2, in glacial acetic acid ). r>

The substance is uniform according to paper chromatography: Rr = 0.949 in n-butanol / glacial acetic acid / pyridine / water (375: 75: 250: 300); R ₁ = 0.876 in n-butanol / glacial acetic acid / water (4: 1: 5).

g) L-tyrosyl-L-glutamine

2 g of 0-tert-butyl-L-tyrosyl-N "'- 4,4 ^r -dimethoxybenzhydryl-L-glutamine are refluxed with 2.5 ml of anisole and 20 ml of trifluoroacetic acid for 5 minutes > Acid concentrated in vacuo and the residue partitioned between water and ether. The aqueous phase is stirred with a weakly basic ion exchanger (acetate form) until a pH of 4. The exchanger is filtered off and Has aqueous filtrate emoppnoi yield 1 g (95% of theory). The substance is pure according to paper chromatography. Rf = 0.471 in n-butanol / glacial acetic acid / pyridine / water (375/75/250/300). Rf = 0.091 in n-butanol / glacial acetic acid / water (4: 1: 5) 4;

Example 2

N-carbobenzoxy-L-valyl-L-glutaminyl-L-phenylalanine-

methyl ester

^J ίο

a) N -Carbobenzoxy-N'M ^ '- dimethoxybenzhydryl-L-glutamine-p-nitrophenyl ester

<x) 5.1 g (10 mmol) of N-carbobenzoxy-N <° -4,4'-dimethoxybenzhydryl-L-glutamine and 1.7 g of p-nitrophenol are dissolved in 20 ml of dimethyl formamide 22 g of dicyclohexylcarbodiimide are added to the cooled solution and left to stand for 2 hours at 0 ° and 1 hour at room temperature, the precipitate is filtered off with suction and ^{about 40 ml of bo water are added to the filtrate.} Yield 3.85 g (61% of theory), melting point 177-178 ° [α]? -10 "(c = 1, in dimethylformamide). ⁶ '

β) 2 g (5 mmol) of N-carbobenzoxy-L-glutamine-p-nitrophenyl ester are dissolved in 25 ml of glacial acetic acid

solved. To this are added 1.2 g of 4,4'-dimethoxy benzhydrol and 1 drop of conc. sulfur acid. It is left to stand overnight at room temperature, crystals separating out The next day it is diluted with about 30 m of water and the crystal pulp is suctioned off. The Kri Stalls are boiled with alcohol and vacuumed. Yield 2.8 g (90% of theory) mp 175-178 °.

b) N-carbobenzoxy-N "'- 4.4'-dimethoxybenzhydryl-L-glutamine I-L-phenylalanine methyl ester

λ) 2.2 g (5 mmol) of N-carbobenzoxy-L-gluten Aniinyl-L-phenylalanine methylers are in 25 ml of glacial acetic acid dissolved. Add 1.2 g of 4,4'-dimethoxybenzhydrol and 1 drop conc. Sulfuric acid. Leave to stand overnight and work like uiiici example 2 a / p) uui. Yield 2.7g (81% of theory). M.p. 200-204 ° [λ] -7.3 (C = 1, in dimethylformamide).

Production of the N-carbobenzoxy-L-glutaminyl-L-phenylalanine methyl ester used as the starting material:

10.8 g L-phenylalanine methyl ester hydro

chloride are dissolved in 100 ml of tetrahydrofuran. It is cooled to 0 ° and treated with 6.8 ml of triethylamine. The mixture is stirred for 10 minutes and then a solution of 20.1 g of N-carbobenz \) xy-L-glutamiii-4-nitrophenyl ester in 100 ml of tetrahydrofuran / dimethylformamide (9: 1) is added. After standing for 3 days at room temperature, the mixture is concentrated and the residue is partitioned between ethyl acetate and water. The ethyl acetate phase is washed with 2N hydrochloric acid, sodium bicarbonate solution and water and concentrated. The residue is recrystallized from methanol / water (1: 1). Yield 14.25 g (65% of theory). F 181-182 ° [«] _o -10.45 ° (r = 7 in Oimpthvlfnrmamifi ^

ß) 2.4 g of L-phenylalanine methyl ester hydrochloride are added to 20 ml of dimethylformamide. To this end, 1.4 ml of triethylamine are added dropwise with stirring. The mixture is stirred for 10 minutes at room temperature and then a solution of 6.3 g (10 mmol) of N-carbobenzoxy

N ^<u -4,4'-dimethoxybenzhydryI-L-glutamine-p-nitrophenyl ester in dimethylformamide 7: and left to stand for several days at room temperature. The precipitate is filtered off with suction and the filtrate is concentrated. The residue is boiled with methanol, cooled and filtered off with suction. Yield: 5.05 g (76% of theory), melting point 201-204 °.

c) N-carbobenzoxy-L-valyl-N ^a) -4,4'-dimethoxybenzhydryl-L-glutaminyl-L-phenylalanine methyl ester

2.16 g (4 mmol) of N-carbobenzoxy-L-valyl-L-glutaminyl-L-phenyl-alanine methyl ester are dissolved in 20 ml of glacial acetic acid. To this are added 036 g of dimethoxybenzhydrol and 1 drop of conc. Sulfuric acid and let stand overnight at room temperature. The next day is worked up as in Example 2a) β) .

Yield 2.65 g (86.4% of theory). F 242-245 °, [λ] "-8.0 (c = 1, in dimethylformamide).

Production of the N-carbobenzoxy-L-valyl-L-glutaminyl-L-phenylalanine methyl ester used as the starting material:

8.8 g of N-carbobenzoxy-L-glutaminyl-L-phenylalanine methyl ester are dissolved in 30 ml of glacial acetic acid. Add 30 ml HBr / glacial acetic acid and leave to stand for 1 hour at room temperature. An oil is precipitated with ether, which is rubbed with ether and dried in a high vacuum. The amorphous mass formed is poured into methylene chloride and treated at 0 "with 2.8 ml of triethylamine and a solution of N-carbobenzoxy-L-valine anhydride (prepared from 10 g of carbobenzoxy-I-valine and dicyclohexylcarbodiimide in methylene chloride). It is left overnight stand in the refrigerator and sucks the precipitate from. with methyl chloride is washed. the precipitate is recrystallized from methanol. yield 2.9 g, F 235-236 ° [<x \ i> -4 "(c = I in dimethylformamide).

d) N-carbobenzoxy-L-valyl-L-glutaminyl-L-phenylalanine methyl ester

385 mg (0.5 mmol) of N-carbobenzoxy-L-valyl-N ^ü) -4,4'-dimethoxybenzhydryl-L-glutaminyl-L-phenylalanine methyl ester are dissolved in 3 ml of trifluoroacetic acid with 03 ml of anisole. The mixture is left to stand for 3 hours at room temperature and concentrated in vacuo at room temperature. The residue is triturated with ether, filtered off with suction and washed well with ether. Yield 265 mg (98% of theory), melting point 238-239 °
[at] -4.0 (c = Ί in dimethylformamide).

Example 3
N-carbobenzoxy-L-asparaginyl-L-tyrosine methyl ester

a) N-carbobene? .oxy-N '"- 4,4'-dimethoxybenzhydryl-L-asparaginyl-O-tert-butyl-L-tyrosine methyl ester

24.5 g (50 mmol) of N-carbobenzoxy-N <"- 4,4'-dimethoxybenzhydryl-L-asparagine are dissolved in 150 ml of DimcihySiWinanuu hydrochloride, cools to -10 °, 6.8 ml of triethylamine are added with stirring, left at this temperature for 10 minutes and finally a solution of 11 g of dicyclohexylcarbodiimide in a little dimethylformamide is added to the reaction mixture puts in the refrigerator overnight. The next day the precipitate is suctioned off and the filtrate is concentrated. The residue is boiled with methanol, cooled and suctioned off. Yield: 28.05 g (77% (LTh.), F 208-209 ° [α] ! ί + 3.65 (c = 2, in dimethylformamide).

b) N-carbobenzoxy-L-asparaginyl-L-tyrosine methyl ester

1.45 g (2.02 mmol) of N-carbobenzoxy-N <»- 4,4'-dimethoxybenzhydryl-L-asparaginyl-O-tert-butyl-L-tyrosine methyl ester are dissolved with 1 ml of anisole in 10 ml of trifluoroacetic acid . After three hours of standing at room temperature, it is concentrated in vacuo at room temperature and the residue is triturated well with ether, filtered off with suction and washed with ether. Yield 846 mg (94% of theory), melting point 197-199 ° [α] ^! i + 7.75 ° (c = 1 in dimethylformamide).

Production of the N-carbobenzoxy-N "'- 4,4'-dimethoxybenzhydryl- used as starting material

L-asparagins:

27 g of N-carbobenzoxy-L-asparagine (0.1 mol) are dissolved in 300 ml of hot glacial acetic acid and reacted as in Example I b) ä). Yield 47.5 g (96.5% of theory), melting point 176-180 °
[«] +2.425 (c = 2, in dimethylformamide).

Example 4
N '"- 4.4'-Dimethoxybenzhydryl-L-asparagine-methyl-

ester hydrochloride
a) N '"- 4,4'-dimethoxybenzhydryl-L-asparagi! i

1.3 g of asparagine (10 mmol) and 2.4 g of 4,4'-dimethoxybenzhydrol (10 mmol) are added to 50 ml of glacial acetic acid. To do this, 0.54 ml of conc. Sulfuric acid and stir until everything is dissolved (about 1 hour). Then 2 g of anhydrous sodium acetate are added and the mixture is concentrated. The residue is partitioned between sodium acetate solution and ethyl acetate. A gelatinous precipitate separates out and is filtered off with suction and washed with water and ethyl acetate. The gelatinous residue is recrystallized from water. Yield 2.1 g (58.6% of theory),
[α]? + 9.75 (c = 2. in glacial acetic acid). F 226-230 °.

h) 49.2 g of N-orbohenzoxy-N <"- 4.4'-dimethoxybenzhydryl-L-asparagine are suspended in 400 ml of glacial acetic acid and mixed with Pd catalyst. In the The suspension is passed in hydrogen with stirring until everything is dissolved and no CO2 more is created. The catalyst is filtered off with suction and the filtrate is concentrated. The residue is mixed with Sodium acetate solution triturated, suction filtered, washed well with water and dried over P2O5. Yield 33.6 g (94% of theory).

c) N-carbobenzoxy-N ^w -4,4'-dimethoxybenzhydryl-L-asparagine methyl ester

4.05 ε N-carbobenzoxy-N ^w -4,4'-dimethoxybenzhydryl-L-asparagine are esterified with diazomethane as in Example 1 c) Yield after recrystallization from ethyl acetate / petroleum ether: 3.4 g (82% of theory), 188-190 ° [λ] " -4.35 ° (c = 2 in dimethylformamide).

d) N ™ -4,4'-dimethoxybenzhydryl-L-asparagine methyl ester hydrochloride

153 g of N-carbobenzoxy-N ^ü> -4,4'-dimethoxybenzhydryl-L-asparagine methyl ester are hydrogenated as in Example 1 d) Yield 10 g (81%), melting point 186-188 ° [«]? + 23, 1 (c = 2 in methanol).

Example 5

o-Nitrosulfenyl-N ^0> -4,4'-dimethoxybenzhydryl-L-asparagine-cyclohexylamine salt

33.6 g of N ^B -4,4'-dimethoxybenzhydryl-L-asparagine are dissolved in 46 ml of 2N sodium hydroxide solution and 116 ml of dioxane, while maintaining pH 8, 19.6 g of o-nitrosulfenyl chloride and 46 ml of 2N sodium hydroxide solution are added in portions. It is then diluted with 930 ml of water and acidified with citric acid (pH 3) and the aqueous phase is extracted twice with ethyl acetate. The ethyl acetate is treated with sodium sulfate

dried and treated with cyclohexylamine. It's falling a yellow crystal pulp, which is suctioned off and washed with ethyl acetate. Dent removal 47.5 g (84.6% of theory), F 182-184 °.

Example 6

N-carbobenzoxy N "» - 4,4'-dimethoxybenzhydryl-L-glutaminyl-L-leucine methyl ester

5.1 g N-carbobenzoxy-N ^M -4,4'-dimethoxybenz-

hydryl-L-glutamine are in 30ml of absolute tetrahydrofuran solved. 1.7 g of L-leucine methyl ester hydrochloride are added and with stirring 1.4 ml of triethylamine. Within one hour, 1.2 g of methylethinyldiethylamine are left at room temperature with stirring, dissolved in 10 ml of tetrahydrofuran are added dropwise. A thick paste soon emerges, made with tetrahydrofuran is diluted. After everything has dripped in, the mixture is left to stir for 30 minutes, concentrated and distributed Residue between water and a lot of warm ethyl acetate, shake the ethyl acetate phase with 2N citric acid, Sodium bicarbonate solution and water, dry with sodium sulfate and concentrate. The residue will rubbed with petroleum ether. Yield 5.5 g (87% of theory), F 169-17Γ. After recrystallization from ethyl acetate / Petroleum ether: yield 4.4 g (70% of theory), melting point 174-178 ° [α] -10.0 ° (c = 1, in dimethylformamide).

Claims (1)

Patent claims: 1. A process for the preparation of asparagine- and glutamine-containing peptides, characterized in that asparagine and glutamine or their acid-stable derivatives of the general formula (I) G- (A) ^ - NH-CH-CO- (B) ₇ -OR _{] Q} (CH ₂ ). (1) of the general formula (II) G- (AU-NH-CH-CO- (B) ₁₁ -OR