Michael addition of the carbanion of the dithian 7 (derived from O-benzyl vanillin) on butenolide, afforded the saturated lactone 8. Alkylation of the latter with the benzylic bromide 6, followed by regeneration of the carbonyl group gave the α, β-disubstituted lactone 10. Reduction of the ketonic carbonyl group of compound 10 using NaBH 4, followed by treatment with CF 3 CO 2 H and catalytic hydrogenolysis afforded (d, l) α-conidendrin 1.
[Sheldrake, Peter W.; Suckling, Keith E.; Woodhouse, Robert N.; Murtagh, Amanda J.; Herbert, Richard B.; Barker, Alan C.; Staunton, James; Battersby, Alan R. Journal of the Chemical Society - Perkin Transactions 1, 1998 , # 18 p. 3003 - 3009]
