JPS60252455A - Novel preparation of amino acid amide - Google Patents

Abstract

PURPOSE:To obtain the titled compound useful as a raw material for synthesizing natural peptide and its related compound inexpensively in high purity and in high yield without using a specific device, by reacting a phosphorus compound with an amine, reacting the reaction product with an N-prorecting amino acid. CONSTITUTION:At least one phosphorus compound selected from phosphorus chlorides and phosphorus oxyhalides is reacted with an amine shown by the formula I (X and Y are H, 1-7C lower alkyl, aryl, or aralkyl), and then reacted with an N-protecting amino acid (when side chain has functional group, the functional group may be protected). The reaction is carried out in a solvent such as dichloromethane, dioxane, etc. at room temperature - the boiling point of the solvent for 2-8hr. Then, the reaction product is optionally deprotected, to give the aimed compound shown by the formula II (A-CO is amino acid residue in which amino group may be protected).

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a novel method for producing amino acid amides.

Calcitonin, gonadotropin-releasing hormone (LH-1'%H), melanocyte-stimulating hormone (α-MSH), secreti7 (5ecr
ciin), P substance (5ubstance P),
Thyroid-stimulating hormone-releasing hormone (TRH), vasoactive intestinal peptide (VIP), pap plefusin (Vas
Among natural physiologically active peptides, there are many peptides in which the terminal carbogyyl group is amidated, such as (Pharmacia Levy-N13, Bioactive Peptide, Pharmaceutical Society of Japan, Eng. 980), such as (Pharmacia Levy-N13, Bioactive Peptide, Pharmaceutical Society of Japan, Eng. 980). Amino acid amides are extremely important compounds as starting materials for synthesizing these natural peptides and their related compounds.

The N-protected amino acid amide is also a useful substance as a starting material for Okikan β-lactam.

For example, N-benzyloxycarbonyl-L-threoninamide is the starting material for azuthreonam (see JP-A-56-125362).

[Conventional technology]

Conventional methods for producing amino acid amides or mono-protected amino acid amides are as follows: 1) A method of obtaining an amino acid amide by aminolysis of a lower alkyl ester of an amino acid, and then protecting free amine groups as necessary 2. ) A method in which N-my amino acid and amine are directly condensed using a carbodiimide such as dicyclohexylcarbodiimide or ethyldimethylaminepropylcarpodiimide, and then protecting groups are removed as necessary 3) Condensation of N-protected amino acid and alkyl carbonate A method is known in which a mixed acid anhydride is reacted with an amine and then, if necessary, a protecting group is removed.

[Problem that the invention seeks to solve]

However, although these methods are suitable for synthesis on a laboratory scale, they are not suitable for mass production. That is, 1)
To carry out this method, a large excess of ammonia gas and a pressurized reaction vessel are required to prevent leakage of the ammonia gas, which poses problems in terms of cost and safety. Method 2) requires carbodiimide, which is expensive and causes severe rash when attached to the skin, and method 3) requires reaction conditions of -20°C or lower because the mixed acid anhydride is unstable. However, problems remain in terms of price and equipment.

Means for Solving Problem C] Therefore, the present inventors conducted intensive studies to develop a method suitable for mass production of mono-protected amino acid amides, and as a result, a method selected from phosphorus halides and phosphorus oxyhalides was found. and at least one phosphorus compound represented by the general formula (11 (wherein X and Y are the same or different and represent a hydrogen atom, a lower alkyl group having 1 to 7 carbon atoms, an allyl group, or an aralkyl group)) When an amine is reacted with an N-protected amino acid (if the side chain has a functional group, the functional group may be protected), and the protecting group is removed as necessary, the general formula (A -Co indicates an amino acid residue whose amine group may be protected.) It has been found that an amino acid amide represented by the following formula can be obtained.

To explain the present invention in more detail, the phosphorus halides used as the raw material of the present invention include, for example, phosphorus trihalides and phosphorus pentahalides, and specifically, for example, phosphorus trichloride, phosphorus tribromide, Examples include phosphorus pentachloride and phosphorus pentabromide. Examples of the phosphorus oxyhalide include phosphorus oxychloride and phosphorus oxybromide.

The amines used are those represented by the general formula (II), where X and Y are the same or different and represent a hydrogen atom or an alkyl group, an allyl group, or an aralkyl group having 1 to 7 carbon atoms, and are branchable. The object may be branched or circular.

Specific examples of X and Y include lower alkyl groups having 1 to 7 carbon atoms such as methyl group, ethyl group, globyl group, butyl group, pentyl group, hexyl group, and peptyl group, phenyl group, and benzyl group. It will be done.

Specific representative examples of amines of the general formula (Tl) include ammonia, methylamine, ethylamine, propylamine, butylamine, pentylamine, hexylamine,
Examples include heptylamine, dimethylamine, diethylamine, dipropylamine, methylbenzylamine, ethylbenzylamine, aniline, and benzylamine.

The N-protected amino acids used in the present invention are not limited to monoaminomonocarboxylic acids, and may be any amino acid having a functional group in its side chain. Specific representative examples of amino acids include glycine, alanine, β-alanine, ornithine, aspartic acid, asparagine, glutamic acid, glutamine, pyroglutamic acid, histidine, hydroxylysine,
Hydroxyproline, inleucine, leucine, lysine, phenylalanine, florine, serine, threonine,
Examples include tryptophan, tyrosine, valine, phenylglycine, hydroxyphenylglycine, γ-aminobutyric acid, methionine, arginine, and cysteine.

As a protecting group for the N-protected amino acid of the present invention, a protecting group for an amine group used in peptide chemistry can be used, but among these, preferable protecting groups include a benzyloxycarbonyl group, a lower alkoxy group on a phenyl group, and a lower alkyl group on a phenyl group. group, a halogen atom, a benzyloxycarbonyl group having a nitro group (e.g. p-methoxybenzyloxycarbonyl group, p-chlorobenzyloxycarbonyl group,
p-bromobenzyloxycarbonyl group, p-nitrobenzyloxycarbonyl group), tert-alkoxycarbonyl M (e.g. tert-butyloxycarbonyl group, tert-pentoxycarbonyl group), formyl group and phthalyl group are common. be.

When using an amino acid having a functional group in its side chain, this side chain functional group may be protected.

The protecting groups used here can be those normally used in peptide chemistry, depending on the type of side chain functional group. Typical examples of amino acids with side chain functional groups protected are δ -benzyloxycarbonyl or 1-butoxycarbonyl-ornithine, aspartate β-benzyl or t-7'f ester, glutamate γ-benzyl or t-butyl ester, N . 0-benzyl or t
-butylhydroxylysine, O-benzyl or 1-butylhydroxyproline, ε-penzyloxycarbonyl or t-butoxycarbonyllysine, 0-benzyl or t-butylserine, 0-benzyl or t-butylthreonine, 0-benzyl or t Examples include -butyltyrosine, 0-benzyl or t-butylhydroxyphenylchrysine, methionine sulfoxide, N-)yl or nitro or benzyloxycarbonyl arginine, S-benzyl or methoxybenzyl or acetamitomenarcissine.

In addition, steric coordination of amino acids having asymmetric carbon atoms is possible. Specifically, one method is to dissolve phosphorus halide or oxino-lokenized phosphorus (hereinafter abbreviated as phosphorus halides) in the above-mentioned solvent, add amines under water cooling, react, and then form a reaction product. is isolated and N
- A method in which the product is reacted with a protected amino acid, and another method is in which the product is subjected to the next reaction with an N-protected amino acid as a solution without isolating the product.

However, the latter method is preferable in terms of both stability of the reaction product and ease of handling.

The solvent used in the present invention is not particularly limited as long as it does not participate in the reaction, and specific examples include dichloromethane, chloroform, halogenated hydrocarbons such as carbon tetrachloride, and cyclic ethers such as dioxane and tetrahydrofuran. Examples include aromatic hydrocarbons such as benzene, toluene, xylene, and esters such as methyl acetate, ethyl acetate, and n-furopuru acetate.

The amount of phosphorus halide, which is a reaction reagent of the present invention, is not particularly limited as long as it is 0.5 molar equivalent or more relative to the N-protected amino acid, but is preferably 1.0 to 1.5 molar equivalent. The amount of amine is 3 to 10 molar equivalents, preferably 5 to 8 molar equivalents, relative to the phosphorus halide.

The reaction temperature used in the present invention is not particularly limited, but it can usually be carried out between room temperature and the boiling point of the solvent, but the boiling point is 60 to 1
It is desirable to use a solvent at 00°C and conduct the reaction at a temperature at or near the boiling point, and the reaction is usually completed in 2 to 8 hours.

If the N-protected amino acid amide thus produced is itself soluble in the reaction solvent, add water to extract the target compound into the organic solvent layer, and if necessary, wash sequentially with a 5% aqueous sodium bicarbonate solution and saturated saline. After removing the solvent under reduced pressure, it can be easily isolated by adding water or a suitable solvent to crystallize it.

If the target compound does not dissolve in the reaction solvent, it can be isolated by removing the solvent under reduced pressure, adding an extraction solvent, and performing the same operation as above. If the target compound is insoluble in water, it can be isolated by removing the solvent under reduced pressure and then adding water for crystallization.

The isolated N-protected amino acid amide is optionally N-protected.
The protecting group can also be removed by a known method to form an amino acid amide.

Removal of the protecting group may be carried out at a temperature below the boiling point of the solvent, for example -50°C to 150°C, depending on the type of protecting group or the type of solvent.
It can be carried out preferably in the range of -400 to 120°C, and various inorganic and organic solvents can be used as the solvent. Examples of the inorganic solvent include water, liquid ammonia, liquid hydrogen fluoride, etc. Examples of the solvent include C1 to C4 alcohols, aqueous solvents such as acetic acid, dimethylformamide, and dioxane, and acetic acid lower alkyl esters, and these can be used as a mixed solvent depending on the case.

Depending on the type of protecting group, reduction (
For example, methods such as catalytic reduction or reduction with an alkali metal and ammonia), hydrolysis, acid decomposition, and hydrazine decomposition can be mentioned. Table 1 shows preferred types of protecting groups and preferred removal methods.

In Table 1, the ten symbol indicates that the protecting group can be removed, and the method with this symbol is used to remove the protecting group. The - symbol indicates that the method does not remove the protecting group. indicates partial removal or decomposition, indicating that it is not well suited for removing protecting groups.

The protecting groups that can be used in the present invention are not limited to those listed in Table 1, and those commonly used in peptide chemistry can be used.

Furthermore, when an amino acid having a protected functional group in its side chain is used, the protecting group can be removed by a known method if necessary.

〔Effect of the invention〕

According to the present invention, a special reaction device such as a pressurized reaction vessel or a
There is no need for special reaction conditions of 0°G or less, there is no need for expensive raw materials such as carbodiimide, and the amino acid amide of the general formula can be obtained with high purity and high yield without racemization. can. Therefore, the method of the present invention is suitable for mass production of amino acid amides.

Example 1゜Phosphorus trichloride in 30 rnl of chloroform] 37ψ (10
,0 mmol) was added and cooled to 5°C, and 1.02 f (60,0 mmol) of ammonia gas was added to this solution.
Introduce at a temperature range of 20°C. After introduction, N − (ter
t = butyloxycarbonyl)-, T, -valine 2.
16! 12-(10.0 mmol, ) was added, and the mixture was allowed to react under heating and reflux for 7 hours. After the reaction, the reaction solution is concentrated under reduced pressure to remove chloroform, 20 ml of ethyl acetate and 20 m6 of water are added to the residue, and the product is extracted into the ethyl acetate layer.

5% aqueous sodium hydrogen carbonate solution], Q ml
The resulting ethyl acetate layer was dried over anhydrous sodium sulfate, and the solvent was distilled off under reduced pressure to give -(tert-butyloxycarbonyl)-
L-valinamide 1.60! i' (yield 74.3%) is obtained.

Melting point: 156-157°C [α3 product 0-10.1° (C=1.0.acetic acid) This product completely matched the separately synthesized standard product in NMR and IR.

Example 2゜Chloroform 30ml! 1.37 P of phosphorus trichloride (
10.0 mmol) was added and cooled to 5°C, and 0.85 P (50.0 mmol) of ammonia gas was added to this solution.
is introduced at a temperature of 20°C or less. After introduction, N-benzyloxycarbo=#-L-prolife 2.49! i' (1
0.0 mmol) and reacted under heating and reflux for 14 hours. After the reaction, the reaction solution is concentrated under reduced pressure to remove chloroform, 20 ml of water is added to the residue to form a solution, and the pH is adjusted to 8.0 with IN aqueous sodium hydroxide solution. Next, the mixture is extracted twice with 30 ml of ethyl acetate, and the ethyl acetate layer is washed with 15 ml of saturated brine and dried over anhydrous sodium sulfate ram.

The solvent is distilled off under reduced pressure to obtain an oil.

By crystallizing from 2Qrnl of 11-hexane and drying, N-benzyloxycarbonyl-L-prolinamide 2.40PC (yield: 97.6%) is obtained.

Melting point: 87-89°C [α-ear: 0-32.1° (C=2.0.ethanol) This product completely matched the standard product synthesized separately in NMR and IR.

Example 3 Phosphorous trichloride l, 37 in tetrahydrofuran 4 Ornl
fl□ (10,0 mmol) was added and cooled to 5°C, and ammonia gas 1.02 F (60,0 mmol) was added to this solution.
mol) is introduced at a temperature below 20°C. After introduction N-(
2.51P (10.0 mmol) of lanine (p-methoxybenzyloxycarbonyl)-L-7 was added and reacted under heating under reflux for 25 hours. N-(p-methoxybenzyloxycarbonyl)-L-alanine amide was obtained by concentrating the solvent under reduced pressure and distilling it off, followed by the same treatment as in Example 1.
07! i' (yield 82.1%) is obtained.

Melting point: j36-137°C [α]9° +19.5° (C21.0.dimethylformamide) This product completely matched the separately synthesized standard product in NMR and IR.

Example 4゜Chloroform 30m7! Inside is 1.10P of phosphorus trichloride (7
, 9 mmol) and cooled to 5° C., and 0.67 P (39.5 mmol) of ammonia gas was introduced into this solution at a temperature of 20° C. or lower. After introducing one benzyloxyca A
/ Ho= /I/ -L-Phenylalaniy2.36F
(7.9 mmol) and reacted under heating under reflux for 6 hours. After the reaction, the reaction solution is concentrated under reduced pressure to remove the solvent, and then treated in the same manner as in the example to obtain crude crystals.

Further recrystallization from 60 TL of a 50% aqueous methanol solution yields 1.35 P of N-benzyloxycarbonyl-L-phenylalanine amide (yield: 875%).

Melting point: 160-161°C [α 0-7.2° (C=1.0.methanol)] This product completely matched the standard product synthesized separately in NMR and iR.

Example 5 1 phosphorus oxychloride in 300 ml of tetrahydrofuran
Add 5.30 P (0.1 mmol) and cool to 5°C, and add 8.50 P (0.5 mmol) of ammonia gas to this solution.
mol) is introduced at a temperature below 20°C. After introduction of monobenzyloxycarbonyl-L-phenylalanine29.
Add 90 g (0.1 mol) and react under heating under reflux for 6 hours. After the reaction, the reaction solution was concentrated under reduced pressure to remove the solvent and treated in the same manner as in Example 1, followed by 170 m/! of water. N-benzyloxycarbonyl-L-phenylalaninamide 28.005' (
A yield of 940%) is obtained.

Example 6 1. Phosphorus trichloride in 30 ml of chloroform. l0P(7,
9 mmol) was added and cooled to 5°C, and 0.80 P (47.4 vtl) of ammonia gas was added to this solution at a temperature of 2.
Introduce at below 0°C. After introduction, hependyloxycarbonylthreonine 2.00 P C7.9 mmol)
was added, and the mixture was allowed to react under heating and reflux for 10 hours. After the reaction, the reaction solution was concentrated under reduced pressure to remove the solvent, treated in the same manner as in Example], added with LO ml of water, crystallized, and the precipitated crystals were dried several times to obtain N-benzyloxycarbonyl-L. -threonine amino)”0.99P (yield 50%)
is obtained.

Melting point: 82-84°C [α] +23.7° (C=1.0.tetrahydrofuran) This product completely matched the separately synthesized standard product in NMR and I temperature.

Example 7 12.1 phosphorus oxychloride in 200 ml of chloroform
0 P C79.0 mmol) was added and cooled to 5°C.
Ammonia gas 8.00 S' (0,47
mmol) is introduced at a temperature below 20°C. After introduction, N
-Benzyloxycarbonyl-L-threonine 20.0
g-(79.0 mmol) was added thereto, and the reaction was carried out under heating under reflux for 6 hours. After the reaction, the reaction solution was concentrated under reduced pressure to remove the solvent, 100 ml of water was added, and the solution was dissolved by heating. This solution was cooled and the precipitated crystals were dried several times to produce N-benzyloxycarbonyl-L-threoninamide 16.
90P (yield 85.0%) is obtained.

Example 8゜The following procedure was carried out in the same manner as in Example 7, except that tetrahydrofuran was used instead of chloroform in Example 7.
Benzyloxycarbonyl-L-threoninamide 1
．． 6.30P (yield: 82.0%) is obtained.

Example 96 N-benzyloxycarbonyl-L-threoninamide Z6.50P (yield 83.0 %) is obtained.

Example 10゜Phosphorous oxychloride 310P (2
0.0 mmol) was added and cooled to 5°C, and 2.105' (60,0 mmol) of ammonia gas was introduced into this solution at a temperature below 20°C. After the introduction, the precipitated crystals are allowed to stand for 30 minutes at room temperature, washed, and dried to obtain 5.20S', a reaction product containing ammonium chloride.

The reaction product obtained was 5.20 Y- and N-benzyloxycarbonyl-L-threonine 5.0! iL'(19
8 mmol) in benzea 5 Qrnl 75~
React for 3 hours at a temperature of 85°C. After the reaction, the reaction solution is concentrated under reduced pressure to remove the solvent, and then 3Qml of water is added and dissolved by heating to form a solution. The crystals precipitated after cooling are washed and dried to obtain 4.4oP (yield: 88.0%) of paperpenzyloxycarbonyl-L-threoninamide.

Example 11 1.37P (I) of phosphorus trichloride in 30TLl of chloroform
73.66 P (50.0 mmol) was added dropwise under cooling, and the mixture was allowed to react at room temperature for 30 minutes. Add 2.10 P (10.0 mmol) of N-benzyloxycarbonylglycine to this solution.
was added, and the mixture was heated and reacted under reflux for 177 hours. After the reaction, the reaction solution is concentrated under reduced pressure to remove the solvent, and then treated in the same manner as in Example 1 to obtain oily N-benzyloxycarbonylglycine diethylamide 1.58P (yield 60.0%).

This product completely matched the separately synthesized standard product in NMR and IR.

Example 12 1.53 PC1 of phosphorus oxychloride in 50 ml of ethyl acetate
0.0 mrnol ) was dissolved, and benzylamine 6.43 P C60.0 mrnol ) was added dropwise under cooling, and the mixture was allowed to react at room temperature for 30 minutes. Add N-benzyloxycarbo=/l/-JJ-7U=n2.23i to this liquid? [
10.0 mmol) was added and reacted for 4 hours under heating and reflux. After the reaction, 30 ml of water is added and the product is extracted into a solvent. After drying the extract over anhydrous sodium sulfate, the solvent is concentrated and distilled off under reduced pressure to obtain a crude product. Recrystallization from ethyl acetate and cyclohexane yields N-benzyloxyca/
2.90
g-(yield 92.0%) is obtained.

Melting point: 141-142°C [α] +8.7° (C2,0.dimethylformamide) This product completely matched the separately synthesized standard product in NMR and IR.

Example 13 1.53% of phosphorus oxychloride in 50ml of ethyl acetate. P(
10.0 mmol) was dissolved therein, and benzylamine 6.43 P (60.0 mmol) was added dropwise under cooling, followed by reaction at room temperature for 30 minutes. Add 2.10 F (10.0 mmol) of hependyloxylponylglycine to this solution.
was added, and the mixture was allowed to react under heating and reflux for 6 hours. Example 12 below
A crude product is obtained by treatment in the same manner as above. When this product is recrystallized from acetone and water, N-benzyloxycarbonylglycine benzylamide 2.307·(yield: 88.5%) is obtained.

The one with a melting point of 119-120° completely matched the separately synthesized standard product in NMR and IR.

Example J4 1.5 phosphorus oxychloride in 50 ml of tetrahydrofuran
3P (10.0 mmol) was dissolved, and under cooling, 5.23 g of isohentylamine (60.0 mmol,
) was added dropwise and allowed to react at room temperature for 30 minutes. This liquid contains N-
Benzyloxycarbonyl-L-leucine 2.65!
i' (10, Ornmol) was added, and the mixture was allowed to react under heating and reflux for 6 hours. After the reaction, the reaction solution was concentrated under reduced pressure to remove the solvent, 50 rnl of ethyl acetate and 50 ml of water were added to the residue, and the product was extracted into ethyl acetate. Combine the extract with 30 ml of 0.5N hydrochloric acid solution and 5% hydrogen carbonate) 30 ml of IJum aqueous solution
The resulting ethyl acetate solution is dried over anhydrous sulfuric acid and evaporated under reduced pressure to obtain a crude product. The obtained crude product was recrystallized from isopropyl ether to yield 2.80% of sultobenzyloxycarbonyl-L-leucine isopentylamide. 7 (yield: $83.7%).

Melting point 93-94℃ Cα] -18.7° (C= 2.0, -r-
(T/-m) This product completely matched the standard product synthesized separately in NMR and IR.

Example 15゜1.535' of phosphorus oxychloride in 50 ml of chloroform
(10.0 mmol) was added dropwise to the solution under cooling, and 8.10 P (60.0 mmol) of ethylbenzylamine was added thereto, followed by reaction at room temperature for 30 minutes. Add 2.995 N-benzyloxycarbonyl-L-phenylalanine to this solution.
Add L(10, Onunol) and react under heating under reflux for 2 hours. Thereafter, the same procedure as in Example 14 is carried out to obtain an oily crude product. This was subjected to column chromatography using silica gel 3005L and a mixed solvent of toluene and ethyl acetate as a developing solvent. Fractions containing the target product were collected and the solvent was distilled off by concentration under reduced pressure. 2.62P (yield 63.0%) is obtained.

[α　−28° (C21.0. Methanol) This product completely matched the standard product synthesized separately in NMR at 1 liter.

Example 16゜Hebenzyloxycarbonyl-L-proline-,r
Mil' 2.00 F (8.1 mmol) was dissolved in 30 ml of methanol, and palladium black 0.20! i' is added and catalytic reduction is carried out at room temperature and normal pressure for 2 hours. After the reaction, the catalyst is removed from the furnace and the filtrate is concentrated under reduced pressure to remove the solvent, yielding the desired product in the form of an oil. 20 ml of ether is added to the mixture for crystallization, and the precipitated crystals are dried on a muddy soil to obtain L-prolinamide (0.90PC yield: 97.0%).

Melting point: 101-102°C [alpha 5-86.6° (C210.methanol) This product completely matched the standard product synthesized separately in Nu and IR.

Example 17゜N-(p-methoxybenzyloxycarbonyl)-1,
-Alaninamide 2.00! ? (7,9mmo]) and treated in the same manner as in Example 14, an oily LJ-like substance is obtained. Add 1.0ml of isopropylethyl to this.
- 20 ml of hexane is added for crystallization, and the precipitated crystals are separated and dried to obtain 0.681 L-alaninamide (yield 98.0%).

Melting point 71-72℃ [α] 25+6.5° (C=2.0.water) This thing is N
Completely consistent with the separately synthesized standard product in MR and IR5 [-.

Example 18゜N-tert-7'' thyloxycarbonyl-L-valinamide 1.,50F (7.0 mmol) was added to 4N
Dissolve in 10 ml of hydrogen chloride dioxane solution and stir at room temperature for 1 hour.

The solvent was distilled off by concentration under reduced pressure and washed with dry ether to give L-valinamide hydrochloride 1.06s' (yield 99.0
%] is obtained.

Melting point 262-263°C [α]60+34.1° (C=1.0.methanol)
This product completely matched the separately synthesized standard product in NMR and IR.

Patent applicant: Nippon Kayaku Co., Ltd.

Claims (1)

[Scope of Claims] At least one phosphorus compound selected from phosphorus halides and phosphorus oxyhalides and a general formula (wherein X and Y are the same or different, hydrogen atom, carbon number 1 to 7) lower alkyl group, allyl group or aralkyl group), then react with an N-protected amino acid (if the side chain has a functional group, the functional group may be protected), A method for producing an amino acid amide represented by the general formula (A-CO in the formula represents an amino acid residue whose amine group may be protected), which comprises removing a protecting group if necessary.