An Efficient Synthesis of 3,4-Dihydropyran-2-one Derivatives by Lewis Base-catalyzed Tandem Michael Addition and Lactonization

A convenient one-pot preparation of 3,4-dihydropyran-2-one derivatives by Michael addition of silyl enolate derived from phenyl ester with (alpha),(beta)-unsaturated ketones in the presence of a Lewis base catalyst such as tetrabutylammonium phenoxide was developed. In this catalytic cycle, 3,4-dihydropyran-2-ones were produced in good to excellent yields via intramolecular cyclization of in situ formed Michael-adducts.