Manganese-Catalyzed Hydrogenation of Ketones under Mild and Base-free Conditions

Stefan Weber; Julian Brünig; Luis F Veiros; Karl Kirchner

doi:10.1021/acs.organomet.1c00161

Manganese-Catalyzed Hydrogenation of Ketones under Mild and Base-free Conditions

Organometallics. 2021 May 10;40(9):1388-1394. doi: 10.1021/acs.organomet.1c00161. Epub 2021 Apr 22.

Authors

Stefan Weber¹, Julian Brünig¹, Luis F Veiros², Karl Kirchner¹

Affiliations

¹ Institute of Applied Synthetic Chemistry, Vienna University of Technology, Getreidemarkt 9, Vienna A-1060, Austria.
² Centro de Química Estrutural and Departamento de Engenharia Química, Instituto Superior Técnico, Universidade de Lisboa, Av Rovisco Pais, Lisboa 1049-001, Portugal.

Abstract

In this paper, several Mn(I) complexes were applied as catalysts for the homogeneous hydrogenation of ketones. The most active precatalyst is the bench-stable alkyl bisphosphine Mn(I) complex fac-[Mn(dippe) (CO)₃(CH₂CH₂CH₃)]. The reaction proceeds at room temperature under base-free conditions with a catalyst loading of 3 mol % and a hydrogen pressure of 10 bar. A temperature-dependent selectivity for the reduction of α,β-unsaturated carbonyls was observed. At room temperature, the carbonyl group was selectively hydrogenated, while the C=C bond stayed intact. At 60 °C, fully saturated systems were obtained. A plausible mechanism based on DFT calculations which involves an inner-sphere hydride transfer is proposed.