Pyrido [2, 3-d] pyrimidines are synthesized in a two-step procedure from amides and tetrazolo [1, 5-a] pyridine-8-carbonyl chloride. Reaction of the crude imides with triphenylphosphine effects an intramolecular aza-Wittig reaction to afford a variety of substituted pyrido [2, 3-d] pyrimidines in good to moderate yields (30–76%).
