Easy To Synthesize, Robust Organo-osmium Asymmetric Transfer Hydrogenation Catalysts
James P C Coverdale1, Carlos Sanchez-Cano1, Guy J Clarkson1
1Department of Chemistry, University of Warwick, Coventry, CV4 7AL (UK).
Abstract:
Asymmetric transfer hydrogenation (ATH) is an important process in organic synthesis for which the Noyori-type Ru(II) catalysts [(arene)Ru(Tsdiamine)] are now well established and widely used. We now demonstrate for the first time the catalytic activity of the osmium analogues. X-ray crystal structures of the 16-electron Os(II) catalysts are almost identical to those of Ru(II). Intriguingly the precursor complex was isolated as a dichlorido complex with a monodentate amine ligand. The Os(II) catalysts are readily synthesised (within 1 h) and exhibit excellent enantioselectivity in ATH reactions of ketones.
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