Method for the preparation of certain pyridine and quinoline 2,3-dicarboxylic anhydrides

Claim 1

A process for the preparation of a compound of formula: ##STR22## wherein X is hydrogen, halogen or methyl, with the proviso that when Y and Z are taken together to form a ring and YZ is represented by the structure: --(CH 2 ) n --, where n is 3 or 4, then X is hydrogen; Y and Z each are hydrogen, halogen, C 1 -C 6 alkyl, C 1 -C 6 alkoxy, C 1 -C 4 alkylthio, phenoxy, C 1 -C 4 haloalkyl, nitro, cyano, C 1 -C 4 alkylsulfonyl group, or phenyl optionally substituted with one C 1 -C 4 alkyl, C 1 -C 4 alkoxy or halogen; and, when taken together, Y and Z may form a ring in which --(YZ)-- is represented by the structure: --(CH 2 ) n --, where n is an integer selected from 3 and 4, provided that X is hydrogen; or ##STR23## where L, M, Q and R 3 are each hydrogen, halogen, C 1 -C 4 alkyl, C 1 -C 4 alkoxy, C 1 -C 4 alkylthio, C 1 -C 4 alkylsulfonyl, C 1 -C 4 haloalkyl, NO 2 , CN, phenyl, phenoxy, chlorophenyl, methylphenyl, or phenoxy substituted with one Cl, CF 3 , NO 2 or CH 3 group, with the proviso that only one of L, M, Q or R 3 , may represent a substituent other than hydrogen, halogen, C 1 -C 4 alkyl or C 1 -C 4 alkoxy; comprising: reacting one molar equivalent of a compound of formula: ##STR24## wherein X, Y and Z are as hereinabove defined, with from 1 to 6 molar equivalents of phosgene in the presence of a solvent of aliphatic and aromatic hydrocarbons, alkylnitriles, ethers or mixtures thereof; and in the presence of from 0.05 molar equivalent to 0.75 molar equivalent of dimethylformamide, at a temperature range of from -5° C. to +50° C. for a period of time sufficient to essentially complete the reaction.