A phosphine-catalyzed cascade (2+3)/(2+4) cyclization reaction of γ-vinyl allenoates with aldimine esters has been developed to provide a series of chromeno[4,3-b]pyrrole derivatives that contain three contiguous stereogenic centers. The method gives a good yield, excellent chemoselectivity and diastereoselectivity under mild conditions.
![Graphical abstract: Phosphine-catalyzed sequential (2+3)/(2+4) annulation of γ-vinyl allenoates: access to the synthesis of chromeno[4,3-b]pyrroles](http://hg.y866.cn/compound/lib/scimg/usr/1/D1CC04199A.jpg)