Preparation of substituted aromatic carboxamides

A process for preparing an aromatic carboxamide of formula I.a,

• wherein
• RA is independently selected from the group consisting of cyano, 5-(trifluoromethyl)-1,2,4-oxadiazole-3-yl, halogen, C1-C6-alkyl, C1-C6-haloalkyl, C1-C6-alkoxy, and C1-C6-haloalkoxy;
• R is cyano or 5-(trifluoromethyl)-1,2,4-oxadiazole-3-yl;
• n corresponds to the total number of radicals RA attached to the central aromatic ring and wherein n is 0 or 1;
• A1 and A2 are independently selected from nitrogen, C—H, or C—RA;
• and
• wherein no more than one of A1 and A2 is nitrogen;
• R1 is C1-C6-alkyl, C1-C6-alkoxy, C3-C11-cycloalkyl, C3-C8-cycloalkenyl, C2-C6-alkenyl, C2-C6-alkynyl, C1-C6-alkoxyimino-C1-C4-alkyl, C2-C6-alkenyloxyimino-C1-C4-alkyl, C2-C6-alkynyloxyimino-C1-C4-alkyl, C1-C6-alkylamino, diC1-C6-alkylamino, —C(═O)—(C1-C6-alkyl), —C(═O)—(C1-C6-alkoxy), phenyl-C1-C4-alkyl, phenyl-C1-C4-alkenyl, phenyl-C1-C4-alkynyl, heteroaryl-C1-C4-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-C1-C4-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 R1a;
• or
• R1 and R2, 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 R1a;
• wherein
• R1a is halogen, oxo, cyano, NO2, OH, SH, NH2, C1-C6-alkyl, C1-C6-haloalkyl, C1-C6-alkoxy, C1-C6-haloalkoxy, C1-C6-alkylthio, C1-C6-haloalkylthio, C3-C8-cycloalkyl, —NHSO2-C1-C4-alkyl, (C═O)-(C1-C4-alkyl), C(═O)-(C1-C4-alkoxy), C1-C6-alkylsulfonyl, hydroxyC1-C4-alkyl, C(═O)-NH2, C(═O)-NH(C1-C4-alkyl), C1-C4-alkylthio-C1-C4-alkyl, aminoC1-C4-alkyl, C1-C4-alkylamino-C1-C4-alkyl, diC1-C4-alkylamino-C1-C4-alkyl, aminocarbonyl-C1-C4-alkyl, or C1-C4-alkoxy-C1-C4-alkyl;
• R2 is hydrogen, C1-C6-alkyl, C2-C6-alkenyl, C2-C6-alkynyl, C1-C6-alkoxy, C3-C11-cycloalkyl, —C(═O)H, —C(═O)-(C1-C6-alkyl), —C(═O)-(C3-C11-cycloalkyl), or —C(═O)-(C1-C6-alkoxy);
• and wherein any of the aliphatic or cyclic groups in R2 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, C1-C6-alkyl, C1-C6-alkoxy, and C3-C11-cycloalkyl;
• the process comprising:
• step 1:
• charging a reaction vessel with a solvent and an aromatic carboxylic acid chloride of formula II.a,
• step 2:
• establishing a pressure of from 10 to 70 kPa in the reaction vessel;
• step 3:
• metering in an amine compound of formula III,
• HNR1R2 III;
• whereas the process is conducted in the absence of an auxiliary base and is characterized in that the solvent is selected from a carboxylic acid ester of formula V,
• RX-C(═O)—O—RY V
• wherein RX is methyl, ethyl, or propyl;
• RY is C1-C6-alkyl, to obtain the aromatic carboxamide of formula I.a,