Homolytic carbostannylation of alkenes and alkynes with tributylstannyl enolates.

In the presence of AIBN, tributylstannyl enolates derived from aromatic ketones reacted with electron-deficient alkenes and a variety of alkynes to give the corresponding carbostannylated adducts. The reactions with methyl acrylate gave alpha-tributylstannylmethyl-gamma-ketoesters, unlike the known Michael-type reaction of stannyl enolates forming delta-ketoesters. The carbostannylation of alkynes proceeded in an anti addition mode to afford beta,gamma-unsaturated ketones. The reactivity of stannyl enolates as radical transfer agents could be utilized for radical cyclization of 1,6-enynes.