Patent ID: 7009058
Filing Date: 2006-03-07
Classification: C07D

Abstract:
1. A method for preparing a pyridine-2,3-dicarboxylic acid ester of formula: wherein R is C 1-6 -alkyl, C 3-6 -cycloalkyl, aryl or arylalkyl, and R 1 to R 3 , independently of one another, is hydrogen, C 1-6 -alkyl, fluorinated C 1-6 -alkyl, C 1-6 -alkoxy, (C 1-6 -alkoxy)-C 1-6 -alkyl or (C 1-6 -alkoxy)carbonyl, comprising reacting a 2,3-dichloropyridine of formula: wherein R 1 and R 3 are each defined as above, with carbon monoxide and an alcohol of formula: wherein R is defined as above, in the presence of (i) a catalytically active complex of palladium with a diphosphine of formula: wherein R 4 to R 7 , independently of one another, is phenyl, substituted phenyl, C 1-6 -alkyl or C 3-6 -cycloalkyl, and Q is a 1,1′-ferrocenediyl group, and (ii) a base that is selected from the group consisting of alkali metal salts of lower carboxylic acids, alkaline earth metal salts of lower carboxylic acids, alkali metal hydrogen carbonates, alkaline earth metal hydrogen carbonates, alkali metal (di)hydrogen phosphates and alkaline earth metal (di)hydrogen phosphates.