Hydrostannylation-Cross-Coupling Strategy for the Stereoselective Synthesis of Alkylidenemalonates and Related [alpha],[beta]-Unsaturated Esters

A method for the stereoselective synthesis of alkylidenemalonates and related [alpha],[beta]-unsaturated esters by a hydrostannylation-cross-coupling process has been developed. Pd-catalyzed and radical hydrostannylation of propiolate derivatives stereoselectively provided [alpha]-alkoxycarbonyl (E)- and (Z)-vinylstannanes, respectively, which were then converted into alkylidenemalonates by the Stille coupling reaction. A one-pot process was also realizable for the Pd-catalyzed reactions.