Stereoselective synthesis of polysubstituted alkenes through a phosphine-mediated three-component system of aldehydes, alpha-halo carbonyl compounds, and terminal alkenes.

Geometrical control: PPh(3) and methyl acrylate (or acrylamide) are able to mediate the one-pot Wittig reaction of aldehydes with alpha-halo carbonyl compounds for the synthesis of 1,2-disubstituted and trisubstituted alkenes in an excellent stereoselective fashion. Furthermore, the first one-pot, three-component reaction of aldehydes, alpha-halo acetates, and terminal alkenes has been developed in the presence of PPh(3) to produce trisubstituted alkenes with excellent E selectivity (see scheme).