Process for preparing pyridine-2,3-dicarboxylic acid compounds

摘要

A process for preparing pyridine-2,3-dicarboxylic acid compounds of the following formula, which comprises preparing alpha -halo-oxalacetic acid diesters by reacting oxalacetic acid diester alkali metallic salts with an acid and a halogenating agent or by reacting oxalic acid diesters with halo-acetic acid esters, and then reacting the obtained alpha -halo-oxalacetic acid diesters with 2-propenal compounds and ammonia. <IMAGE> wherein R1 and R2 are, identical or different, a lower alkyl group, and R3 is a hydrogen atom or a lower alkyl group. The pyridine-2,3-dicarboxylic acid compounds obtained by the process of the invention are useful as an intermediate for manufacturing agricultural chemicals and pharmaceuticals.