Unexpected α,α′-difluoroethers from Ag(i)F and N-bromosuccinimide reactions of dibenzo[a,e]cyclooctatetraene

Abstract

An unexpected and highly efficient reaction of dibenzo[a,e]cyclooctatetraene with Ag(I)F and N-bromosuccinamide in dichloromethane results in a sequential ring contraction pathway to generate bridged bicyclic α,α′-difluoroether isomers 10 and 11 where the ether oxygen is isotopically labelled from oxygen-18 water. In diethyl ether the same reaction generates the more classical vicinal difluoride isomers 13 and 14.