Long-Range Isomerisation / Cyclopropane Isomerisation / Cycloisomerisation / Aromatisation Reactions Using Multifunctional Rhodium Catalysts; Synthesis of 2,3-Disubstituted Benzofurans

Abstract

Transition-metal-catalyzed chain-walking reactions have emerged as a powerful strategy for remote functionalization of alkenes; however, their integration with C–C bond activation remains largely unexplored. Herein, we report a rhodium-catalyzed reaction that combines long-range alkyl chain walking with selective cyclopropyl C–C bond cleavage within a single catalytic system. In this transformation, migratory alkene isomerization across extended carbon frameworks enables distal activation of a cyclopropylmethyl unit, leading to the efficient formation of substituted benzofurans under mild conditions. Unlike conventional chain-walking processes that terminate in remote functionalization, the present system exploits catalyst migration as a prerequisite for subsequent C–C bond activation at a spatially separated site. Mechanistic investigations, including temperature-controlled and time-resolved NMR studies, support a sequential pathway involving alkene chain walking followed by cyclopropane activation. This work demonstrates a cooperative catalytic strategy that orchestrates spatially separated reaction events and expands the conceptual scope of chain-walking catalysis in organic synthesis.