Copper-catalyzed HFIP-promoted para-selective allylation of phenols via C–C bond activation of gem-difluorinated cyclopropanes

Although ring-opening cross-coupling of gem-difluorocyclopropanes using transition metal catalysts is a well-explored strategy, the development of cost-effective metal catalysts for this transformation is still uncommon. This study presents a copper-catalyzed para-selective fluoroallylation of unprotected phenols achieved through a ring-opening cross-coupling approach. This straightforward method employs an inexpensive and easily accessible catalyst, offers a wide substrate scope, and supports late-stage functionalization of biologically active compounds. Mechanistic investigations suggest that an allyl–Cu(III) intermediate is generated through C–C bond oxidative addition to Cu(I), followed by C–F bond elimination. The para-selectivity is primarily attributed to hydrogen bonding between hexafluoroisopropanol and the phenol.