Highly stereoselective hydrogenation of -pinene over Ir nanoparticles confined in SiO₂ shells

The highly stereoselective hydrogenation of alpha-pinene was very important and challenging in the utilization of natural products at mild conditions. Here, we reported a core-shell catalyst coated with Ir metal particles by mesoporous silica shell, and revealing the dependence of reducing agents during the preparation process. The prepared nano catalyst exhibited excellent performance in the hydrogenation of chiral substance alpha-pinene, especially under very mild conditions (40 C, 1 MPa H2 and 2 h), with a yield of cis-pinane reaching similar to 99 %. The characterization methods revealed that the excellent performance was attributed to the strong hydrogenolysis ability of Ir particles. DFT results further indicated that alpha-pinene can stably adsorb on the edge sites of Ir metal in a cis structure, thereby achieving highly stereoselective hydrogenation. This work utilized heterogeneous catalysis to achieve performance close to that of homogeneous catalysts. The stable core shell structure greatly prolonged the lifespan of the catalyst and overcame the drawbacks of homogeneous catalysts. This work provided more reference cases for chiral hydrogenation.