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 intermol ecular aza-Wittig reaction of 2-(triphenylphosphoranylidene)aminonicot inamides 3 derived from 2-aminonicotinic acid (1), with carboxylic aci d chloride followed by heterocyclization via imidoyl chloride intermed iate 4. The structure of -2-(4-nitrophenyl)-4(3H)-pyrido[2,3-d]pyrimid inone (5b) was established by X-ray crystallographic analysis. This me thodology has been applied also to a novel synthesis of 4(3H)-quinazol inone 14.