Reagent-Controlled Tandem Reactions of Vinyl Epoxides: Access to Functionalized γ-Butenolides

A new approach to functionalized gamma-butenolides based on reagent-controlled tandem reaction sequences of Morita-Baylis-Hillman-type vinyl epoxides is described. The nucleophilic addition of a tertiary phosphine to the electron deficient alkene led to ring-opening of the epoxide followed by lactonization to produce phosphonium ylides, which could undergo Wittig olefination with aryl trifluoromethyl ketones and aryl aldehydes to give 3-alkenyl gamma-butenolides in moderate to good yields and high E/Z selectivity. Tertiary amine promoted the Michael-type addition of carbon- and nitrogen-based nucleophiles to the vinyl epoxides followed by lactonization to provide diverse 3-substituted gamma-butenolides.