Generation of alkylidenecarbenes from 1,1-dibromoalk-1-enes by the reaction with samarium diiodide in hexamethylphosphoric triamide–benzene

Abstract
Reaction of 1,1-dibromoalk-1-enes with samarium diiodide in benzene containing 10% of hexamethylphosphoric triamide (HMPA) affords rearranged alkynes; generation of alkylidenecarbenes is probably involved.