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Herein, we evolve a base-promoted synthesis of 2 H -chromen-2-one and chromeno2,3- 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.
Roshani et al. (2024) studied this question.