Ca II , Yb II and Sm II Bis(Amido) Complexes Coordinated by NHC Ligands: Efficient Catalysts for Highly Regio- and Chemoselective Consecutive Hydrophosphinations with PH 3

The first example of intermolecular hydrophosphination of styrene, 2-vinylpyridine and phenylacetylene with PH catalyzed by bis-(amido) complexes [(Me Si) N] M(NHC) (M=Ca, Yb, Sm) coordinated by NHC ligands is described. The reactions of styrene with PH proceed under mild conditions in quantitative yields to afford only anti-Markovnikov product and allow for the chemoselective synthesis of primary, secondary and tertiary phosphines. Addition of phenylacetylene to PH regardless the initial molar substrates ratio results in the exclusive formation of a tertiary tris-(Z-styryl)-phosphine. Crucial effect of the Lewis base coordinated to the metal ion in precatalyst on catalytic activity in styrene hydrophosphination with PH was demonstrated. Free NHCs were also found to be able to promote addition of PH to styrene, however they provide much lower reaction rates compared to the metal complexes.