Pyrido[2,3-d]pyrimidine derivatives: Synthesis via the intermolecular aza-Wittig reaction/heterocyclization and the crystal structure
Pyrido[2,3-d]pyrimidine derivatives 5 were synthesized by the intermolecular aza-Wittig reaction of 2- (triphenylphosphoranylidene)aminonicotinamides 3 derived from 2- aminonicotinic acid (1), with carboxylic acid chloride followed by heterocyclization vi