Processes for the preparation of pyridine - 2,3 - dicarboxilatos replaced and di - replaced and process for the preparation of nicotinatos replaced

摘要

A method for the preparation of substituted and disubstituted pyridine-2,3-dicarboxylates of formula I …CHEM…wherein R3 is hydrogen, halogen, straight or branched alkyl, alkenyl, phenyl, or substituted-phenyl; R4 and R7 are each hydrogen, straight or branched alkyl, alkenyl, phenyl, or substituted-phenyl; and R5 and R6 are each alkyl; comprising reacting an alpha - @SH Y@ halo- beta -ketoester of formula II …CHEM…wherein R5 and R6 are defined above with an alpha , beta -unsaturated aldehyde or ketone of formula III …CHEM…wherein R3, R4 and R7 are as described in formula I in the presence of a minimum of 2 molar equivalents of an ammonium salt in an organic solvent in a temperature range of ambient temperature to the boiling point of the solvent until the reaction is essentially complete.