A conjugate addition/sulfoxide elimination route to allylic difluorophosphonates

Article abstract of DOI:10.1016/S0040-4039(98)02000-0

Cerium-mediated conjugate additions of (diethoxyphosphinoyl) difluoromethyllithium to cyclic vinyl sulfoxides proceeded smoothly; thermal sulfoxide elimination afforded the products of formal vinylation, attaching the difluoromethylenephosphonato group to an alkenyl carbon atom. With acyclic vinyl sulfoxides, the addition occurred in moderate to poor yield. Addition failed completely in the absence of cerium(III) chloride, and was facilitated by an excess of the reagent.