Process for preparing pyridine carboxylic acid esters

Claim 1

A method for the preparation of substituted and disubstituted pyridine-2-3-dicarboxylates of formula I: ##STR33## wherein R 3 is hydrogen, halogen, C 1 -C 6 straight or branched alkyl, alkenyl, phenyl R 4 and R 7 are each hydrogen, C 1 -C 6 straight or branched alkyl, alkenyl, phenyl, substituted-phenyl; and R 5 and R 6 are each C 1 -C 4 alkyl; comprising reacting a β-ketoester of formula II; ##STR34## wherein R 5 and R 6 are defined above with an α,β-unsaturated aldehyde or ketone of formula III: ##STR35## wherein R 3 , R 4 and R 7 are as described in formula I in the presence of at least 1 molar equivalent of an ammomium salt in a solvent in the presence of a dehydrogenation catalyst and at a temperature range of ambient temperature to the boiling point of the solvent until the reaction is essentially complete.

Claim 2

A method for the preparation of substituted and disubstituted pyridine-2-3-dicarboxylates of formula I: ##STR33## wherein R 3 is hydrogen, halogen, C 1 -C 6 straight or branched alkyl, alkenyl, phenyl R 4 and R 7 are each hydrogen, C 1 -C 6 straight or branched alkyl, alkenyl, phenyl, substituted-phenyl; and R 5 and R 6 are each C 1 -C 4 alkyl; comprising reacting a β-ketoester of formula II; ##STR34## wherein R 5 and R 6 are defined above with an α,β-unsaturated aldehyde or ketone of formula III: ##STR35## wherein R 3 , R 4 and R 7 are as described in formula I in the presence of at least 1 molar equivalent of an ammomium salt in a solvent in the presence of a dehydrogenation catalyst and at a temperature range of ambient temperature to the boiling point of the solvent until the reaction is essentially complete.

Claim 14

A method for the preparation of substituted nicotinates having the structure: ##STR36## wherein R 3 is hydrogen, halogen, C 1 -C 6 straight or branced alkyl, alkenyl, phenyl; R 4 and R 7 are each hydrogen, C 1 -C 6 straight or branced alkyl, alkenyl, phenyl, substituted-phenyl; R 6 and R 8 are each C 1 -C 4 alkyl; comprising reacting the ketoester of formula V: ##STR37## wherein R 6 and R 8 are as defined for formula IV, with an α,β-unsaturated aldehyde or ketone of formula III: ##STR38## wherein R 3 , R 4 and R 7 are as described in formula IV, 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.

Claim 15

A method for the preparation of substituted nicotinates having the structure: ##STR36## wherein R 3 is hydrogen, halogen, C 1 -C 6 straight or branced alkyl, alkenyl, phenyl; R 4 and R 7 are each hydrogen, C 1 -C 6 straight or branced alkyl, alkenyl, phenyl, substituted-phenyl; R 6 and R 8 are each C 1 -C 4 alkyl; comprising reacting the ketoester of formula V: ##STR37## wherein R 6 and R 8 are as defined for formula IV, with an α,β-unsaturated aldehyde or ketone of formula III: ##STR38## wherein R 3 , R 4 and R 7 are as described in formula IV, 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.