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

Org Lett. 2024 Oct 25;26(42):9114-9119. doi: 10.1021/acs.orglett.4c03436. Epub 2024 Oct 11.

Abstract

Herein, we evolve a base-promoted synthesis of 2H-chromen-2-one and chromeno[2,3-c]pyrrole scaffolds via (4 + 2) annulation of α-alkylidene succinimides with 2-hydroxyphenyl-substituted para-quinone methides (p-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. Several control experiments were performed to understand the reaction mechanism.