Phosphine-catalyzed domino reaction: a novel sequential [2+3] and [3+2] annulation reaction of γ-substituent allenoates to construct bicyclic[3,3,0]octene derivatives

We have successfully developed a novel and efficient phosphine-catalyzed sequential [2+3] and [3+2] annulation reaction of gamma-substituent allenoates to construct bicyclic[3, 3, 0]octene derivatives. The protocol uses readily available gamma-substituent allenoates as the starting materials, inexpensive PBu3 as the catalyst, and the corresponding products were obtained in good to excellent yields under mild conditions.