Base-Promoted Chemodivergent Construction of 2-Chromen-2-one and Chromeno[2,3-]pyrrole Scaffolds from -Quinone Methides and α-Alkylidene Succinimides.

Herein, we evolve a base-promoted synthesis of 2-chromen-2-one and chromeno[2,3-]pyrrole scaffolds via (4 + 2) annulation of α-alkylidene succinimides with 2-hydroxyphenyl-substituted -quinone methides (-QMs). Extremely selective and switchable cyclizations were obtained by modifying the base. This metal-free protocol is highlighted by its mild reaction conditions and broad substrate scope, and the viability of the existing protocol was additionally illustrated by gram-scale synthesis and further modification.