1. Diboron-mediated palladium-catalyzed asymmetric transfer hydrogenation using the proton of alcohols as hydrogen source
- Author
-
Bo Wu, Zi-Biao Zhao, Yi Luo, Jimin Yang, Shu-Bo Hu, Changbin Yu, and Yong-Gui Zhou
- Subjects
inorganic chemicals ,Hydrogen ,Proton ,Chemistry ,chemistry.chemical_element ,Hydrogen transfer ,General Chemistry ,Transfer hydrogenation ,Combinatorial chemistry ,Palladium ,Catalysis - Abstract
The developments of hydrogen sources stand at the forefront of asymmetric reduction. In contrast to the well-studied alcohols as hydrogen sources via β-hydride elimination, the direct utilization of the proton of alcohols as a hydrogen source for activator-mediated asymmetric reduction is rarely explored. Herein we report the proton of alcohols as a hydrogen source in diboron-mediated palladium-catalyzed asymmetric transfer hydrogenation of 1,3-diketones and indoles, providing a series of chiral β-hydroxy ketones and indolines with excellent yields and enantioselectivities. This strategy would be useful for the synthesis of chiral deuterium-labelled compounds due to the ready availability of deuterium-labelled alcohols. Mechanistic investigations and DFT calculations revealed that active chiral Pd-H species was generated from the proton of alcohols by activating of tetrahydroxydiboron, hydrogen transfer was the rate-determining step, and the reaction preferred Pd(0)-catalyzed mechanism.
- Published
- 2021