Palladium-catalyzed reactions of acetoxyenynes with triorganoindium reagents

The reaction of 1-acetoxy-2,7- and 2,8-enynes with triorganoindium reagents in the presence of 5 mol % palladium catalyst provides cyclic and/or acyclic substitution products depending upon substrate structure. Enynes bearing secondary acetates, quaternary centers, or heteroatoms furnish high yields of carbocyclic or heterocyclic substitution products. NMR studies show that a single trisubstituted alkene stereoisomer is formed in the reaction. A more atom-efficient procedure for the cyclization–substitution process utilizing heteroleptic indium reagents is presented.