NL1010867C2 - Process for the preparation of amino acid amides or derivatives thereof. - Google Patents

Description

- 1 - PN 9904 PROCESS FOR THE PREPARATION OF AMINO ACID AMIDS OR DERIVATIVES THEREOF 5

The invention relates to a process for the preparation of compounds of the general formula (1) R2 ^ ^ 4

R1-j- (CH2) n. JS

10 \ / ^ R3 (1)

NHR II

O

wherein Rx and R2 represent an amino acid residue, n is 0 or 15 and R3 and R4 each independently represent an unsubstituted or substituted alkyl group, or (hetero) aryl group or H, wherein an amino acid R2R2 is -C (NHR) - (CH2 n-COOH (with R is H, alkyl or eryl), is contacted in a solvent with an activating agent and then with an amino donor of the general formula NHR3R4.

Such a method is known from WO-A-9626213. This publication describes the preparation of amino acid amides by activation of 25 amino acids using hexafluoroacetone or chloral as an activating agent and contacting the activated amino acid with an amino donor.

However, the use of hexafluoroacetone and chloral is particularly disadvantageous because of the toxic nature of these compounds. In addition, these compounds are expensive and difficult to recycle, making such a process commercially unattractive.

The object of the invention is to provide a method with which amino acid amides or derivatives thereof can be prepared in a high yield and in a commercially attractive process.

This is accomplished by acting as activating agent I Q 1 C? 5 Γ - 2 - use a dihalosilane compound, wherein the halosubstituents may each independently be F, Cl, Br or I.

It has in fact been found that in the method according to the invention use can be made of a non-toxic and inexpensive activating agent which, moreover, can usually be recycled simply if desired. It is believed that by using dihalosilanes, the 10 amino acid used as starting material is both activated on the carboxyl and protected on the amino-N, possibly to form a cyclic reactive intermediate, and that the amino-N is simultaneously deprotected in the amidation . Moreover, it has been found that during coupling the 15 amino acid does not racemize.

The amino acids to be used in the method according to the invention are α-amino acids (n = 0) or β-amino acids (n = 1), in particular natural or non-natural aliphatic or aromatic amino acids RjR2-20 C- (NHR) - (CH2) n-COOH wherein Rx and R2 are, for example, H, aryl, for example phenyl or p-hydroxylphenyl, or an unsubstituted or substituted alkyl group, for example methyl or benzyl; or an unsaturated group, for example dihydrophenyl. Preferably Rj. or R2 equals H. R represents H, alkyl or aryl.

For example, amino acid amides can be prepared from the corresponding amino acid by the method of the invention.

Primary or secondary amines, preferably primary amines whose amino group is bound to a primary, a secondary or a tertiary C atom, 1, -4 - 3 - preferably to a primary C atom can then be used as an amino donor. of the formula NH2 -R3 wherein R3 represents an alkyl group with 1-10 C atoms. Examples of suitable amines are benzylamine, methylamine, dimethylamine, i-butylamine, n-hexylamine, i-propylamine, 2-butylamine and tert-butylamine.

The method can also prepare, for example, β-lactam antibiotics, for example by using as a amino donor a β-lactam core, and as an amino acid an unsubstituted or substituted phenylglycine or derivative thereof, for example D-phenylglycine, Dp-hydroxyphenylglycine or D-dihydrophenylglycine . In principle, any β-lactam core can be used; in particular a β-lactam core with the general formula (1) 15

Ro Y

h2n __ / 20 J-γζ 25 where R0 represents H or an alkoxy group with 1-3 C atoms; Y represents CH2, O, S or an oxidized form of sulfur; and z stands for / ...

XCH3 \ \ \ 11/1 u CH3, / \ Ri, \ Ri, or / VCH: where Rj. for example H, halogen, an alkyl group with 1-5 C-atoms, alkoxy group with 1-5 C- - 4 atoms, an alkenyl group with 2-5 C atoms, a (thio) ether group with 1-5 C- atoms, an ester group with 2-10 C atoms, an amide group with 1-5 C atoms, a cycloalkyl group with 4-8 C atoms, an aryl or a heteroaryl group with 6-10 C atoms, the groups may be optionally substituted, for example, with a halogen or a hydroxy, alkyl, an aryl, a carboxy, an alkoxy or a (substituted) amino group having 0-8 C atoms, and wherein the carboxylic acid group is optionally a ester group.

Suitable examples of β-lactam nuclei that can be used in the method according to the invention are penicillin derivatives, for example 6-aminopenicillanic acid (6-APA), and cephalosporin-15 derivatives, for example a 7-aminocephalosporanoic acid with or without a substituent on the 3- site, for example 7-aminocephalosporanoic acid (7-ACA), 7-aminodesacetoxycephalosporanoic acid (7-ADCA), 7-amino-3 - [(Z) -1-propenyl] -3- (desacetoxymethyl) -cephalosporanoic acid 20 (7-PACA) , 7-amino-3-chloro-cef-3-em-4-carboxylic acid (7-ACCA) and 7-amino-3-chloro-8-oxo-1-azabicyclo [4.2.0] oct-2-en- 2-carboxylic acid.

The method according to the invention can also be used very suitably in the preparation of peptides, wherein the amino donor is, for example, a carboxyl-protected amino acid, dipeptide or oligopeptide, for example an ester or amide, for example L-phenylalanine methyl ester.

The reaction conditions applied in the process according to the invention are not particularly critical and are partly determined by the stability of the reactants used, and / or intermediates obtained and / or end products obtained. The temperature at which the activation and coupling is carried out is preferably between -20 and 150 ° C, in particular between -10 and 50 ° C; the temperature during activation and the coupling does not have to be chosen equally.

Suitable solvents that can be used are, for example, aprotic, preferably polar and / or basic solvents, for example pyridine, N, N-dimethyl-acetamide (DMA), N-methyl-pyrrolidone (NMP), dioxane, tetrahydrofuran (THF) acetonitrile , dimethyl sulfoxide (DMSO), 1,2-dichloroethane and triethylamine.

Preferably, the activation with the dihalosilane compound is carried out in the presence of a base, for example, a tertiary amine, for example diisopropylethylamine (DIPEA) or triethylamine (Et3N), or pyridine. It may be advantageous to also use the base as a solvent. Preferably, the base 20 is added before the siian compound is added. It can be advantageous to choose as base a base of which the basity is higher than the basicity of the amino donor. Preferably an amount of base is added which is at least the amount necessary to neutralize the released hydrogen halide.

Suitable dihalosilane compounds which can be used as activating agents in the process according to the invention are, for example, compounds of formula (2) 1010867- - 6 -R3 X-Si-X (2) 5 R4 in which the substituents X are both independently F, Cl, Br or I represent, preferably Cl, and R3 and R4 each independently represent H, an alkyl group 10 or an aryl group with 1-10 C atoms, preferably H and / or an alkyl group with 1-3 C- atoms, especially dimethyldichlorosilane or monomethyl dichlorosilane.

The amount of the dihalosilane compound to be used is preferably between 0.5 and 3 eq., Preferably between 1 and 1.5 eq. relative to the amount of amino acid to be activated. If desired, an additional amount of dihalosilane compound may be used to compensate for any water or alcohol present in the solvent, amino acid or amino donor.

After the (optionally partial) activation of the amino acid, the amino donor is added, whether or not dissolved in an (inert) solvent, for example the same solvent as used in the activation. Preferably, an amount of an amino donor of 0.5-10 eq., Preferably 1-3 eq., Calculated relative to the amount of amino acid to be activated is used. In cases where the amino donor neutralizes (part of) the hydrogen halide released, a corresponding amount of amino donor will have to be added additionally.

The process has the additional advantage that when starting from an aspartic acid, S ~ i * ^ ^ -ν '' - 7 - which in addition to an α-carboxyl functionality also has a β-carboxyl functionality, the amino donor with very high selectivity the α-carboxyl group can be linked.

The invention will now be further elucidated by means of the following examples, without, however, being limited thereby.

General procedure, used in Examples I to III 10 To a suspension of the relevant amino acid or derivative thereof (2.0 mmol) in the respective dry solvent (10 ml) was carried out under a nitrogen atmosphere, after optionally adding a base (base and amount as indicated in the tables) added 2.2 mmol silane compound. In some cases, a clear solution was obtained; in other cases a slurry. After stirring for 1 minute, the appropriate amine was added (number of equivalents as indicated in the tables). After stirring at room temperature for 16 hours, the conversion of the amino acid to the coupling product was determined by TLC (thin layer chromatography) (system A: CHCl3 / Methanol / NH3, 60/45/20, v / v / v; system B: sec.butanol / HC00H / H2O, 75/15/10, v / v / v or system C: n-25 butanol / acetic acid / ethyl acetate / H20, l / l / l / l, v / v / v / v) . The reaction mixture was evaporated under reduced pressure and the residue was purified by preparative column chromatography over silica gel eluting with a gradient of CH 2 Cl 2 / methanol 100: 0 -> 95: 5, v / v. Hereby, the coupling product was obtained pure in a yield as indicated in the tables.

- 8 -

Example I

The general procedure was followed for different amino acids and amino donors, with pyridine as solvent and dimethyldichlorosilane {Me2SiCl2) as silane compound. The results are shown in Table 1.

TABLE 1 10 amino acid base amino donor yield L-phenylalanine benzylamine; 3 98% eq.

L-phenylalanine benzylamine; 98% eq.

L-phenylalanine benzylamine; 5 70% i; 21 eq.

L-phenylalanine Et3N; benzylamine; 3 80% 2 eq. eq.

L-phenylalanine DiPEA; benzylamine; 3 80% 2 eq. eq.

L-phenylalanine methylamine; 5 82% eq.

L-phenylalanine-i-butylamine; 3 81% eq.

L-phenylalanine-n-hexylamine; 3 85% eq.

L-phenylalanine - i-propylamine; 5 5% 2) eq.

L-phenylalanine-2-butylamine; 5 ~ ShZ) eq.

i-9-N-methylbenzylamine; 80% glycine eq.

β-alanine - benzylamine; 5 60% eq.

Temperature during the addition of the reactants was -20 ° C; then room temperature.

21 conversion based on TLC analysis 5

Example II

Influence of solvent and / or base with L-phenylalanine as amino acid and dimethyldichlorosilane as silane compound and benzylamine (5 eq.) As amino donor. 10 The general procedure was followed; the results are shown in table 2.

- 10 -Table 2

Solvent base yield pyridine - 98% DMA 1 25% * NMP 1 25% * _____; 10% * CH3CN 1 10% * THF · Et3N; 2 eq. 10% * CH 2 Cl 2 Et 3 N; 2 eq. 10% * DMA Et3N; 2 eq. 80% * NMP Et3N; 2 eq. 80% *

Dioxane Et3N; 2 eq. 10% * 1,2-dichloroethane Et3N; 2 eq. 30% * MSO Et3N; 2 eq. 25% * CHCl 3 Et 3 N; 2 eq. 30% * CH3CN Et3N; 2 eq. 50% * __ _ __ 5 * conversion based on TLC analysis

Example III

Influence of the silane compound.

The general procedure was followed with 10 different silane compounds and amino donors with L-phenylalanine as amino acid and pyridine as solvent without additional base. The results are shown in Table 3.

O <λ o 7. ,, f O; u Ο V (^ - 11 - label l

Silane compound amino donor (5 eq.) Yield (i-propyl) 2SiCl2 benzylamine 30% li3) ”CH3 (H) SiCl2 benzylamine 90% CH3 (H) SiCl2 benzylamine 70% 21 CH3 (H) SiCl2 i-butylaraine 50% CH3 (H ) SiCl2 i-propylamine 10% 3) CH3 (H) SiCl2 2-butylamine 10% 31 CH3 (phenyl) SiCl2 benzylamine 75% CH3 (phenyl) SiCl2 i-butylamine 65%

CH3 (phenyl) SiCl2 i-propylamine 10% JI

(C2Hs) 2SiCl2 benzylamine 20-30% 31

L) The temperature was 110 ° C

2) (see footnote 11 to Table 1) 3) results based on TLC analysis

Example IV

10 Synthesis of a β-lactam antibiotic

To a suspension of D-phenylglycine (0.90g, 6.0mmol) in dry pyridine (30ml) was added dimethyldichlorosilane (0.85g, 6.6mmol), and the reaction mixture was stirred at 20 min. ° C.

Then 6-aminopenicillanic acid (6-APA, 6.5 g, 30.0 mmol) was added to the resulting clear solution and the temperature was raised to 60 ° C. After various reaction times, approximately 100 mg samples were taken from the reaction mixture and analyzed by 20 HPLC. To this end, the samples were added to 50 ml s ^. ». - 1 - 12 - of a make-up solution, containing 97% by volume of 50 mM Η3Ρ04 buffer pH = 6.0 and 3% by volume of 1-propanol. The following HPLC conditions were used: - column: Nucleosil 120-3 Ci8, 250 mm x 4 mm 5 - gradient elution:

t = 0 min: 100% A, 0% B t = 1.5 min: 100% A, 0% B t = 6.5 min: 70% A, 30% B t = 10 min: 70% A, 30 % B

10 in which A = 50 mM aqueous H3PO4 buffer pH = 3 B = 50 vol% A and 50 vol% acetonitrile - flow rate: 1.0 ml / min - temperature: 40 ° c - injection volume: 25 μΐ15 - detection: photometric at a wavelength of 220 nm.

Under the above conditions, D-phenylglycine, 6-APA and the corresponding β-lactam antibiotic ampicillin elute at resp. 3.60 min., 4.25 min. And 11.35 min.

Pure (independently synthesized) reference materials were used for the quantification of these three components.

Result: After a reaction time of 20 hours, it was found that 38 mol% of the starting material D-phenylglycine had been converted to the desired β-lactam antibiotic ampicillin.

Example V

Synthesis of a dipentide 30 To a suspension of L-phenylalanine (L-phe 0.99 g, 6.0 mmol) in dry pyridine (30 ml) was added dimethyldichlorosilane (0.85 g, 6.6 mmol), - 13 - and the reaction mixture was stirred at 20 ° C for 15 minutes.

Then, a solution of L-phenylalanine methyl ester (L-PM, 5.37 g, 30.0 mmol) in 10 ml of dichloromethane 5 was added to the resulting clear solution. After various reaction times, 100 to 200 mg samples were taken from the reaction mixture and analyzed by HPLC. To this end, these samples were added to 100 ml of a make-up solution containing 50% by volume of methanol and 50% by volume of aqueous 0.05 M H3 PO4 buffer 10 (pH = 3.00). The following HPLC conditions were used: column: Inertsil 5 ODS-3, 250 mm x 3 mm.

- gradient elution:

t = 0 min: 98% A, 2% B t = 35 min: 10% A, 90% B

15 wherein A = 10 mM H3PO4 and B = acetonitrile flow rate: 1.2 ml / min.

- temperature: 40 ° C

- injection volume: 20 μΐ - detection: photometric, at a wavelength of 210 nm 20 and 257 nm.

Under the above conditions, L-Phe, L-PM and the dipeptide L-Phe-PheOMe elute at resp.

4.1, 5.5 and 10.8 min. For the quantification of these three components, pure (independently synthesized) reference materials were used.

Result: After a reaction time of 24 hours, it was found that 17 mol% of the starting material L-Phe had been converted to the desired dipeptide L-Phe-L-PheOMe. It should be noted here that the reaction continued to progress so that higher conversions are achievable.

* »- 14 -

Example VI

Synthesis of an L-aspartyl amide with high α selectivity

To a suspension of L-aspartic acid (L-5 Asp, 26.6 g, 200 mmol) in triethylamine (730 g, containing 0.2 wt% water) was added dimethyldichlorosilane (37.7 g, 292 mmol) and the reaction mixture was stirred at 20 ° C for 30 min. Benzylamine (116.6 g, 1089 mmol) 10 was then added to this slurry and the slurry was stirred at room temperature for 24 h. A 2.0 g homogeneous sample from this reaction mixture was diluted with 9.0 g of methanol and 1.50 g of 25% aqueous NH 3 to give a clear sample. 200 mg of this sample was taken up in 50 ml of eluent (see below).

The following HPLC conditions were used: - column: Nucleosil 120-5 Cj.8, 50 mm x 4 mm - eluent: a solution of 1.882 g l-hexanesulfonic acid sodium salt and 0.450 g K2HPO4 in 750 ml water was adjusted to pH 3.00 with H 3 PO 4 and after adding acetonitrile (50 ml), the total volume was made up to 1000 ml with water.

- flow rate: 2.0 ml / min

25 - temperature: 22 ° C

- injection volume: 40 μΐ - detection: photometric at a wavelength of 210 nm

Under the above conditions, L-Asp, L-30 aspartyl-p-benzylamide, benzylamine, L-aspartyl-α-benzylamide and L-aspartyl-α, β-dibenzylamide elute at, respectively. 0.29, 2.37, 4.77, 7.09 and> 25 min. For the 101 06 6 7 · * - 15 - quantification of these components, use was made of pure (independently synthesized) reference materials.

5 Result ·. after 2 hours, it was found that 0.3 mol% of the starting material L-Asp had been converted to L-aspartyl-α-benzylamide and that 0.20 mol% of the starting material L-Asp had been converted to L-aspartyl-p- benzylamide. In addition, no L-aspartyl-ct, β-dibenzylamide could be detected. The above conversion corresponds to a cx selectivity of 99.6%.

'<' ·, - - ~

Claims (11)

1. Process for the preparation of compounds of the general formula (1) R 1 -1 (CH 2) / N / R 3 (1) A method according to claim 1, wherein a primary amine is used as an amino donor. The method of claim 2, wherein the amino group of the primary amine is linked to a primary C atom. The method according to claim 1, wherein a β-lactam core is used as the amino donor. R4 is used in which the substituents X each independently represent F, Cl, Br or I, and R3 and R4 each independently represent H, an alkyl group or an aryl group. A method according to claim 1, wherein a carboxyl-protected amino acid dipeptide or oligopeptide is used as the amino donor. A method according to any one of claims 1 to 5, wherein an activating agent of the general formula (2) - 17 - r3 x-si-x (2) A method according to claim S or 7, wherein X represents Cl. 8. The method of claim 7 wherein R3 = H or CH3 and R4 = CH3. A method according to any one of claims 1-8 wherein a base is added. 10. A method according to any one of claims 1-9, in which an aspartic acid is used as the amino acid. NHR IIO where Rx and R2 represent an amino acid residue, n is 0 or 1 and R3 and R4 are each independently 15 H, a substituted or unsubstituted alkyl group or (hetero) aryl group in which an amino acid R 1 R 2 -C (NHR) - (CH 2) n -COOH with R is H, alkyl or aryl, is contacted in a solvent with an activating agent and then 2. with an amino donor of the general formula NHR3R4 r, characterized in that a dihalosilane compound is used as the activating agent. 11. Method as described and illustrated by the examples. COOPERATION TREATY (PCT) REPORT ON NEWNESS RESEARCH OF INTERNATIONAL TYPE IDENTIFICATION OF THE NATIONAL APPLICATION Characteristic of the applicant or of the authorized representative * 9904 NL Dutch application no. Filing date 1010867 December 22, 1999 Priority date invoked Applicant (Name) DSM NV Date of request of International Type Granted by International Organization for International Research USA) to the request for an International Type Investigation No. SN 32247 EN I. SUBJECT CLASSIFICATION (Where different classifications apply, indicate all rating symbols) According to International Classification (IPC) Int. Cl. 6: C 07 K 1/08, C 07 K 1/10, C 07 C 231/02, C 07 D 499/08, C 07 D 499/10 II. FIELDS OF TECHNIQUE EXAMINED Minimum documentation examined Clauification system Clauifieatiesymüolen In. Cl.6 C 07 K, C 07 C, C 07 D Documentation other than minimum documentation insofar as such documents are included in the areas examined I i NO RESEARCH POSSIBLE FOR CERTAIN CONCLUSIONS (comments on supplementary sheet) IV · I 1 LACK TO UNITY OF INVENTION (comments on supplement sheet) Éorm PCT / ISA / rOKaJ 07.1979 ✓ -