P2O5-promoted efficient and diastereoselective synthesis of substituted 5-methylene-dihydropyran-2,6-diones and 3-methylene-3,4-dihydropyran-2-ones

摘要

A simple, efficient, and diastereoselective synthesis of 5-methylene-dihydropyran-2,6-diones and 3-methylene-3,4-dihydropyran-2-ones from substrates afforded by the S-N(2) reaction between the acetyl derivatives of the Baylis-Hillman adducts and methylacetoacetate or acetylacetone or benzoyl acetone via saponification followed by P2O5-mediated cyclization is described.