Anti-Markovnikov terminal and gem-olefin hydrosilylation using a κ4-diimine nickel catalyst: selectivity for alkene hydrosilylation over ether C–O bond cleavage

Abstract

The phosphine-substituted α-diimine Ni precursor, (^Ph₂PPrDI)Ni, has been found to catalyze alkene hydrosilylation in the presence of Ph₂SiH₂ with turnover frequencies of up to 124 h⁻¹ at 25 °C (990 h⁻¹ at 60 °C). Moreover, the selective hydrosilylation of allylic and vinylic ethers has been demonstrated, even though (^Ph₂PPrDI)Ni is known to catalyze allyl ester C–O bond hydrosilylation. At 70 °C, this catalyst has been found to mediate the hydrosilylation of ten different gem-olefins, with turnover numbers of up to 740 under neat conditions. Prior and current mechanistic observations suggest that alkene hydrosilylation takes place though a Chalk–Harrod mechanism following phosphine donor dissociation.