[P, C] Chelate Cobalt(I)-Catalyzed Distinct Selective Hydrosilylation of Alkenes under Mild Conditions

The industrialization of alkene hydrosilylation catalyzed by cheap metals has become a research hotspot in recent years. Recently, we have found that [P, C] chelate cobalt(III) hydrides are active catalysts in the hydrosilylation of alkenes, but in this catalytic system, the real catalyst is [HCo(PMe 3 ) 3 ], and the [P, C] chelate ligand was not involved in the catalytic reaction. In this paper, to study the effect of the [P, C] chelate ligand on the hydrosilylation of alkenes, a [P, C] chelate cobalt(I) complex, [(Me 3 P) 3 Co( o -Ph 2 P-C 6 H 4 -C═O)] ( 1 ), was prepared and used as a catalyst for the hydrosilylation of alkenes. To our surprise, it was found that complex 1 as a catalyst exhibits more efficient performance for the selective hydrosilylation of alkenes compared with the related [P, C] chelate cobalt(III) hydride, and the selectivity for aromatic alkenes is 100% Markovnikov but the selectivity for aliphatic alkenes is almost 100% anti -Markovnikov. The catalytic conditions (2.5 h, 30 °C) are very mild. For this catalytic system, the reaction activity of aliphatic alkenes is greater than that of aromatic alkenes. In the study of the catalytic mechanism, the intermediate with a coordinated η 2 -(Si–H) bond is considered as a real catalyst. The catalytic mechanism is proposed on the basis of experimental information and literature reports.