Triethylborane-induced radical reaction of alkynylgallium with α-halo carbonyl compounds

Treatment of terminal acetylenes with butyllithium, followed by an addition of gallium trichloride, afforded the corresponding alkynylgallium reagents. The reaction of the resulting alkynylgallium with alpha-halo carbonyl compounds in the presence of triethylborane as a radical initiator provided beta,gamma-acetylenic carbonyl compounds in good yields.