Tin Radical Catalyzed Three-Component Coupling Reaction of Alkynes,Carbon Monoxide,and Amines

摘要

Treatment of terminal alkynes with pressurized carbon monoxide,tributyltin hydride (30 mol%) and AIBN in the presence of a large excess of amines,led to give good yields of alpha-methylene amides via acetylene-carbonylations.The reaction may start with the addition of tributyltin radical to the alkyne terminus,followed by carbonylation of the resulting vinyl radicals.The generated alpha-ketenyl radicals then undergo the three consecutive processes,(1) nucleophilic trapping of a carbonyl group by amines leading to the production of 1-hydroxyallyl radicals,(2) 1,4-H migration to give alpha-keto radicals,(3) beta-elimination to give a-methylene amides and regenerating the tributyltin radical.