PREPARATION OF SUBSTITUTED 4-(N'-HYDROXYCARBAMIMIDOYL)BENZOIC ACIDS

Abstract

The present invention relates to a process for the preparation of substituted 4-(N′-hydroxy-carbamimidoyl)benzoic acids, which can be obtained by nitrilase catalyzed hydration of substituted terephthalonitriles of formula (II) in an aqueous medium to afford (ammonium) 4-cyanobenzoic acids (IIa). The hydration is followed by treatment of the aqueous reaction medium with hydroxylamine or a salt thereof to afford amidoximes (I).

##STR00001##

Claims

1. A process for preparing amidoxime compounds of formula I, ##STR00010## wherein R is halogen, C.sub.1-C.sub.4-alkyl, C.sub.1-C.sub.4-haloalkyl, C.sub.1-C.sub.4-alkoxy, or C.sub.1-C.sub.4-haloalkoxy; n is 0, 1 or 2; the process comprising i. providing an aqueous medium comprising water, one or more nitrilase, and a terephthalonitrile of formula II, wherein the variables n and R have the meaning as defined for compound of formula I; ##STR00011## ii. incubating the aqueous medium to obtain 4-cyanobenzoic acid of formula IIa or a salt thereof in an aqueous medium, wherein the variables n and R in 4-cyanobenzoic acid IIa have the meaning as defined for compound of formula I; ##STR00012## iii. removal of biological material from the aqueous medium; iv. treatment of the aqueous medium obtained in step iii with hydroxylamine or a salt thereof.

2. The process according to claim 1, wherein n is 0 in compounds of formulae I, II, and IIa.

3. The process according to claim 1, wherein the terephthalonitrile II is added to the aqueous medium before incubation in a concentration between 1% and 30% by weight.

4. The process according to claim 1, wherein the aqueous medium in process steps i and ii has a pH value of 4 to 9.

5. The process according to claim 1, wherein the aqueous medium in step ii is incubated at a temperature in the range of from 10° C. to 50° C.

6. The process according to claim 1, wherein 1 to 3 molar equivalents of hydroxylamine or a salt thereof are used in step iv, based on the amount of terephthalonitrile II.

7. The process according to claim 1, wherein the temperature in step iv is in a range of from 0° C. and 100° C.

8. The process according to claim 1, wherein the compound of formula I is isolated by filtration or centrifugation after step iv.

9. The process according to claim 2, further comprising reacting the compound of formula I to obtain a compound of formula III ##STR00013##

10. The process according to claim 9, further comprising reacting the compound of formula III to obtain a compound of formula IV ##STR00014##

11. The process according to claim 9 or 10, further comprising reacting the compound of formula III or IV with a compound of formula V,
R.sup.1—NH—R.sup.2  V wherein R.sup.1 is C.sub.1-C.sub.6-alkyl, C.sub.1-C.sub.6-alkoxy, C.sub.3-C.sub.11-cycloalkyl, C.sub.3-C.sub.6-cycloalkenyl, C.sub.2-C.sub.6-alkenyl, C.sub.2-C.sub.6-alkynyl, C.sub.1-C.sub.6-alkoxyimino-C.sub.1-C.sub.4-alkyl, C.sub.2-C.sub.6-alkenyloxyimino-C.sub.1-C.sub.4-alkyl, C.sub.2-C.sub.6-alkynyloxyimino-C.sub.1-C.sub.4-alkyl, C.sub.1-C.sub.6-alkylamino, diC.sub.1-C.sub.6-alkylamino, —C(═O)—C.sub.1-C.sub.6-alkyl, —C(═O)—O—C.sub.1-C.sub.6-alkyl, phenyl-C.sub.1-C.sub.4-alkyl, phenyl-C.sub.1-C.sub.4-alkenyl, phenyl-C.sub.1-C.sub.4-alkynyl, heteroaryl-C.sub.1-C.sub.4-alkyl, phenyl, naphthyl, or a 3- to 10-membered saturated, partially unsaturated or aromatic mono- or bicyclic heterocycle, wherein the ring member atoms of said mono- or bicyclic heterocycle include besides carbon atoms further 1, 2, 3 or 4 heteroatoms selected from N, O and S as ring member atoms with the provision that the heterocycle cannot contain 2 contiguous atoms selected from O and S; and wherein the heteroaryl group in the group heteroaryl-C.sub.1-C.sub.4-alkyl is a 5- or 6-membered aromatic heterocycle, wherein the ring member atoms of the heterocyclic ring include besides carbon atoms 1, 2, 3 or 4 heteroatoms selected from N, O, and S as ring member atoms with the provision that the heterocycle cannot contain 2 contiguous atoms selected from O and S; and wherein any of the above-mentioned aliphatic or cyclic groups are unsubstituted or substituted with 1, 2, 3, or up to the maximum possible number of identical or different groups Ria; or R.sup.1 and R.sup.2, together with the nitrogen atom to which they are attached, form a saturated or partially unsaturated mono- or bicyclic 3- to 10-membered heterocycle, wherein the heterocycle includes beside one nitrogen atom and one or more carbon atoms no further heteroatoms or 1, 2 or 3 further heteroatoms independently selected from N, O, and S as ring member atoms with the provision that the heterocycle cannot contain 2 contiguous atoms selected from O and S; and wherein the heterocycle is unsubstituted or substituted with 1, 2, 3, 4, or up to the maximum possible number of identical or different groups R.sup.1a; wherein R.sup.1a is halogen, oxo, cyano, NO.sub.2, OH, SH, NH.sub.2, C.sub.1-C.sub.6-alkyl, C.sub.1-C.sub.6-haloalkyl, C.sub.1-C.sub.6-alkoxy, C.sub.1-C.sub.6-haloalkoxy, C.sub.1-C.sub.6-alkylthio, C.sub.1-C.sub.6-haloalkylthio, C.sub.3-C.sub.8-cycloalkyl, —NHSO.sub.2—C.sub.1-C.sub.4-alkyl, —(C═O)—C.sub.1-C.sub.4-alkyl, —C(═O)—O—C.sub.1-C.sub.4-alkyl, C.sub.1-C.sub.6-alkylsulfonyl, hydroxyC.sub.1-C.sub.4-alkyl, —C(═O)—NH.sub.2, —C(═O)—NH(C.sub.1-C.sub.4-alkyl), C.sub.1-C.sub.4-alkylthio-C.sub.1-C.sub.4-alkyl, aminoC.sub.1-C.sub.4-alkyl, C.sub.1-C.sub.4-alkylamino-C.sub.1-C.sub.4-alkyl, diC.sub.1-C.sub.4-alkylamino-C.sub.1-C.sub.4-alkyl, aminocarbonyl-C.sub.1-C.sub.4-alkyl, or C.sub.1-C.sub.4-alkoxy-C.sub.1-C.sub.4-alkyl; R.sup.2 is hydrogen, C.sub.1-C.sub.6-alkyl, 02-C.sub.6-alkenyl, 02-C.sub.6-alkynyl, C.sub.1-C.sub.6-alkoxy, C.sub.3-C.sub.11-cycloalkyl, —C(═O)H, —C(═O)—C.sub.1-C.sub.6-alkyl, —C(═O)—C.sub.3-C.sub.11-cycloalkyl, or —C(═O)—O—C.sub.1-C.sub.6-alkyl; and wherein any of the aliphatic or cyclic groups in R.sup.2 are unsubstituted or substituted with 1, 2, 3, or up to the maximum possible number of identical or different radicals selected from the group consisting of halogen, hydroxy, oxo, cyano, C.sub.1-C.sub.6-alkyl, C.sub.1-C.sub.6-alkoxy, and C.sub.3-C.sub.11-cycloalkyl; to obtain a compound of formula VI ##STR00015##

12. The process according to claim 11, further comprising reacting the compound of formula VI to obtain a compound of formula VII ##STR00016##

13. The process according to claim 12, wherein in compounds of formula V, VI and VII R.sup.1 is methyl, ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, iso-butyl, cyclopropyl, 2-methoxyiminoethyl, bicyclo[1.1.1]pentan-1-yl, or phenyl; and wherein the phenyl group is unsubstituted or substituted with 1, 2, 3 or up to the maximum possible number of identical or different radicals selected from the group consisting of fluorine, chlorine, cyano, OH, NH.sub.2, methyl, ethyl, methoxy, trifluoromethyl, trifluoromethoxy, difluoromethyl, difluoromethoxy, and cyclopropyl; and R.sup.2 is hydrogen, methyl, or ethyl.

14. The process according to claim 12, wherein in compounds of formula V, VI and VII R.sup.1 is methyl, 2-methoxyiminoethyl, bicyclo[1.1.1]pentan-1-yl, 2-fluoro-phenyl, 4-fluoro-phenyl, or 2,4-difluorophenyl; in particular methyl or 2-fluoro-phenyl; and R.sup.2 is hydrogen.

Description

WORKING EXAMPLES

[0107] The present invention is further illustrated by means of the following working example:

Example 1

Preparation of 4-(N′-hydroxycarbamimidoyl)benzoic acid

[0108] Terephthalonitrile (108.9 g, 0.85 mol) and water (881 g) were placed in a glass reactor at 25° C. and heated to 30° C. The biocatalyst suspension in 50 mM potassium phosphate buffer @ pH 7 (10 g, Escherichia coli TG10+ pDHE-Com expressing a nitrilase from Comamonas testosteroni) was added once the temperature reached 30° C. The mixture was stirred using a three-stage cross-arm stirrer for 23 hours. Completion of reaction was indicated by absence of residual solid terephthalonitrile (visual test). A 50 wt-% NaOH solution in water (10 g) was added after the reaction to adjust the pH to 8.73. Mixing was continued for 30 minutes. The suspension was filtered via a 0.22 μm single use filter to remove the biocatalyst. The clear filtrate of the 4-cyanobenzoic acid ammonium salt was used without further purification in the next step. The aqueous filtrate solution of the 4-cyanobenzoic acid salt (516 g, 0.43 mol, 500.05 mL−c=0.85 mol/L−ρ=1.03 kg/L) was placed in a glass reactor and hydroxylamine (37.9 g, 0.57 mol, 1.35 eq, 50% solution in water) was added over a period of 5 min (slightly exothermic, T˜29.5° C.). The resulting solution was warmed to 40° C. and stirred for 6 hours. The solution was then cooled to 25° C. and the pH of the solution is then adjusted to 4.4 by using an aqueous HCl solution (63.4 g, 0.64 mol, 37 wt-% in water). Water (20 g) was added to ensure proper stirring of the suspension. The mixture was then cooled to 5° C. and filtrated (nutsch). Solids were washed with pre-cooled water (110 mL at 5° C.) and dried under reduced pressure at 50° C. to afford the desired product (74.5 g, 94.7%, purity 97.4%).

Example 2

[0109] Terephthalonitrile (89 g, 0.695 mol) and water (900 g) were placed in a glass reactor at 25° C. and heated to 30° C. Biocatalyst suspension in 50 mM potassium phosphate buffer pH 7 (11 g, Escherichia coli TG10+ pDHE-Com expressing a nitrilase from Comamonas testosteroni) was added once the temperature reached 30° C. The mixture was stirred using a three stage cross-arm stirrer for 23 hours. Completion of reaction was indicated by absence of residual solid terephthalonitrile (visual test). After the bioconversion, the reaction suspension was removed from the reactor and filtered through Celite535 to remove the bulk quantity of biocatalyst. Subsequently the material was filtered via a 0.22 μm single use filter to remove residual biocatalyst. The clear filtrate contained the 4-cyanobenzoic acid ammonium salt in a concentration translating into 8.82 wt-% 4-cyanobenzoic acid and was used without further purification in the next step.

[0110] A part of the aqueous filtrate solution of the 4-cyanobenzoic acid salt (130 g, 8.82 wt-%, 77.9 mmol) was placed in a glass reactor and hydroxylamine (8 g, 121.1 mmol, 1.55 eq, 50% solution in water) was added over a period of 20 min at 50° C. The resulting mixture was stirred for 4 hours at unchanged temperature. The solution was then cooled to 21° C. and the pH of the solution was adjusted to <3 by addition of a 50% sulfuric acid solution (13 g, 66 mmol, 50 wt-% in water) in order to precipitate the product. The resulting suspension was then cooled to 5° C. and filtrated. Solids were washed twice with pre-cooled water (50 mL each portion, at 5° C.) and dried under reduced pressure (70° C./25 mbar) over 12 hours to afford the desired product (14.1 g, yield 94.2% of theory, purity 93.8% determined by quant. NMR).

[0111] The nitrilase from Comamonas testosteroni that was used in examples 1 and 2 above was retrieved from a sequence from a publicly accessible database (its primary structure/sequence is deposited in GenBank on 29 Nov. 1995 under the accession number L32589.1 (Nucleotide) and AAA82085.1 (Aminoacid)) and corresponds to Seq. ID 2, SEQ amino acid 29, SEQ ID nucleic acid 28, Identity 90% in table 1 of PCT/EP2020/051288. Comamonas testosteroni is a ubiquitous soil bacterium that has been sampled prior to August 1990 without any known Nagoya Protocol obligations (DSMZ entry DSM 38, Country of origin unknown).