Metal-free transfer hydrochlorination of internal C-C triple bonds with a bicyclo[3.1.0]hexane-based surrogate releasing two molecules of hydrogen chloride

The development and application of a transfer hydrochlorination reagent based on a trichlorinated bicyclo[3.1.0]hexane core that transfers two molecules of HCl per molecule of surrogate to a π-basic substrate under B(C 6 F 5 ) 3 catalysis is reported. Lewis acid-assisted chloride abstraction followed by thermal electrocyclic cyclopropyl-to-allyl cation ring opening releases ring strain as a previously unexploited driving force. A non-protic surrogate that contains two molecules of HCl for the synthesis of alkenyl chlorides from internal alkynes is reported. The HCl transfer is catalyzed by B(C 6 F 5 ) 3 and driven by release of strain and aromatization.