Scope and Mechanism of Stannylalumination of 1-Alkynes

Article abstract of DOI:10.1021/jo00282a021

Terminal acetylenes react with Bu3SnAlEt2 in the presence of Cu₊ or Pd₀ catalysts to give 1,2-dimetallo-1-alkenes in highly regio- and stereoselective reactions.These intermediates can be selectively functionalized at the vinyl-aluminum bond to provide vinylstannanes, which upon transmetalation and further reaction with electrophiles give stereodefined trisubstituted olefins.In sharp contrast to the normal behavior of alkylaluminum reagents, this process tolerates a number of functional groups including OH, OAc, OTHP, and Br.Mechanistic investigations suggest that the addition of Bu3SnAlEt2 to 1-alkynes proceeds via stannylcupration followed by capture of the stannylcuprate adduct by electrophilic aluminum.