Effects of a bidentate phosphine ligand on palladium-catalyzed nucleophilic substitution reactions of propargyl and allyl halides with thiol

Palladium-catalyzed nucleophilic substitution reactions of propargyl halides 1 with n-PrSH proceed smoothly with excellent yield by using dppe (dppe > P(t-BU)(3) > PPh3 > P(biphenyl)(t-Bu)(2)) in polar soluent (DMF-d(7) > chloroform-d > benzene-d(6)). A suitable catalytic intermediate in this reaction is discussed. In addition, dppe was found to be an efficient ligand in the reaction of allyl chloride with thiol.