Divergent amine-catalyzed [2+2] annulation of allenoates with azodicarboxylates: facile synthesis of 1,2-diazetidines

A divergent DABCO-catalyzed [2+2] annulation reaction of allenoates with azodicarboxylates is developed for an easy synthesis of 3-alkylidene-1,2-diazetidines.