Modular Regiodivergent Synthesis of Benzo-Fused Isocoumarins by a Cyclopropane Aromatization Strategy

Reported herein is an electrophile-modulated aromatization reaction of highly functionalized cyclopropanes to structurally diverse benzoisocoumarins featuring concurrent formation of the benzenoid and alpha-pyrone rings under mild conditions. An aromatization reaction of the proposed benzonorcaradiene intermediates prepared independently revealed a crucial role of the neighboring olefinic substituents in determining whether the cyclopropane ring expansion is followed by a 1,2-shift of the ester group.

Automated summary

This study reports an electrophile-modulated aromatization reaction of highly functionalized cyclopropanes, which can produce structurally diverse benzoisocoumarins with the formation of both benzenoid and alpha-pyrone rings under mild conditions. The study also reveals the crucial role of neighboring olefinic substituents in determining whether a 1,2-shift of the ester group follows the cyclopropane ring expansion.