One-pot and regioselective synthesis of 3,4-dihydroquinazolines by Sequential Ugi/Staudinger/aza-Wittig reaction starting from functionalized isocyanides

A new one-pot and regioselective synthesis of 3,4-dihydroquinazolines by Ugi/Staudinger/aza-Wittig sequence has been developed. The Ugi-type reaction of 2-azidobenzylisocyanide, aldehyde, secondary amine and acid produced an azide intermediate, which was then treated with triphenylphosphine to give 3,4-dihydroquinazolines regioselectively in good overall yields by Staudinger/aza-Wittig reaction at room temperature.