Palladium catalyzed asymmetric hydrophosphination of α,β- and α,β,γ,δ-unsaturated malonate esters - efficient control of reactivity, stereo- and regio-selectivity

Both PC-cyclometalated and PCP-pincer type palladium catalysts have recently been found to be robust and efficacious catalysts for the asymmetric P-H addition reaction involving activated olefins. Our studies on the asymmetric P-H addition of diphenylphosphine to malonate ester and alpha,beta,gamma,delta-alkylidenemalonate ester revealed for the first time that the catalyst choice can have a dramatic impact in terms of reactivity as well as regio- and stereo-control for this asymmetric hydrofunctionalization reaction. Besides showing significantly contrasting reactivity and stereoselectivity in the hydrophosphination reaction involving malonate ester, in the case of alpha,beta,gamma,delta-alkylidenemalonate ester, a novel regiodivergent method was developed with the 1,4-adduct being obtained exclusively with the PC-catalyst while the pincer catalyst produced only the 1,6-adduct.