gamma-Lactone Formation in the Addition of Benzenesulfonyl Bromide to Diene and Enyne Esters.

The gem-dialkyl effect has been used to promote the formation of functionalized gamma-lactones in the addition of benzenesulfonyl bromide to diene and enyne esters. Introduction of 3 mol % of pyridine into the reactions increases the yields of lactones produced from tertiary esters. Formation of the C(alpha)-C(beta) bond of gamma-lactones has been achieved in both C(alpha)-->C(beta) and C(beta)-->C(alpha) radical cyclization directions.