Cycloisomerization of 7-en-2-yn-1-ones to bicyclo[3.1.0]hexanes using electrophilic fluorination or chlorination agents†

Abstract

In contrast to the π-electrophilic transition metal-catalyzed cycloisomerization of enynes, systematic studies on the reaction of enynes by activation of carbonyl groups conjugated to alkynes are lacking. Herein, we report the metal-free cycloisomerization of 7-en-2-yn-1-ones to gem-difluorinated and gem-chlorofluorinated bicyclo[3.1.0]hexanes using electrophilic halogenating agents.