Difluorinative ring expansions of benzo-fused carbocycles and heterocycles are achieved with p-(difluoroiodo)toluene.

Abstract

A chemoselective fluorinative ring expansion has been realized using the hypervalent iodine (HVI) reagent p-TolIF2, which delivers β,β-difluoroalkyl arenes in yields up to 89% and allylic gem-difluorides in yields up to 78%. This rapid reaction exploits the ambiphilic nature of alkenes and allenes, and incorporates both fluorine atoms of the (difluoroiodo)arene in the products. The mechanism involves a 1,2-phenyl shift, which provides access in one step to important fluorinated building blocks for bioactive molecule synthesis.