Difluoroallenyl Bromide as a Wide‐Ranging Difluoromethylene Cation Equivalent: SN2 Substitution of Difluoropropargyl Bromide through Sequential SE2′ and SN2′ Reactions

A synthetic challenge: a two-step conversion of RCF2Br into RCF2Nu has been achieved (see scheme; Nu=nucleophile). Nucleophilic substitution at a difluoromethylene carbon atom is carried out by using a functionalized difluoroallene as a CF2 cation equivalent. The resulting product contains a triisopropylsilyl (TIPS)–acetylenic linkage suitable for further functionalization.