Sulfinylmethyl Phosphines as Chiral Ligands in the Intermolecular Pauson−Khand Reaction

A new family of enantiomerically pure p-tolyl and tert-butyl sulfinylmethyl phosphine ligands is described. Ligands with an extra chiral center in the central carbon atom were prepared by phosphinylation of benzyl and homobenzyl sulfoxides. Ligand exchange reaction of these compounds with Co2-alkyne complexes afforded up to 6:1 dr. The resulting bridged complexes were tested in the intermolecular Pauson−Khand reaction to provide up to 97% ee.