A new synthesis of imidazolinones and quinazolinones by intramolecular aza-Wittig reaction is described. Readily available azido substituted imides 4, 6, 10, and 12 reacted with triphenylphosphine or tributylphosphine to afford the corresponding imidazolinones 1, 7 and quinazolinones 2, 12 via the Staudinger reaction, followed by an intramolecular aza-Wittig reaction.