Process for preparing pyridinecarboxylic esters

摘要

A process for preparing pyridinecarboxylic esters of the general formula: wherein R1 is hydrogen, a C1-C6-alkyl group, a C1-C4-alkoxycarbonyl group or a C1-C4-alkoxymethyl group, R2 is a C1-C4-alkyl group and X is chlorine or bromine. The pyridinecarboxylic esters are obtained by reacting the corresponding 2,3-dihalopyridines with carbon monoxide and a C1-C4-alkanol in the presence of a weak base and a complex of palladium with a bis(diphenylphosphine). Pyridinecarboxylic esters are intermediates for preparing herbicides and drugs against fibrotic diseases.