Decarbonylative Transfer Hydrochlorination of Alkenes and Alkynes Based on a B(C 6 F 5 ) 3 -Initiated Grob Fragmentation.

Readily available cyclohexa-2,5-dien-1-ylcarbonyl chloride derivatives are introduced as bench-stable HCl surrogates for transfer hydrochlorination of terminal and internal alkenes as well as selected alkynes. The stepwise Grob fragmentation of those acyl chlorides into chloride, carbon monoxide, a low-molecular-weight arene, and a proton is promoted by B(C 6 F 5 ) 3 . This decarbonylative transfer process enables the addition of HCl across C-C double and triple bonds with Markovnikov selectivity at room temperature.