Acylative Dynamic Kinetic Resolution of Secondary Alcohols: Tandem Catalysis by HyperBTM and Bäckvall’s Ruthenium Complex

Kinens, A.; Balkaitis, S.; Ahmad, O. K.; Piotrowski, D. W.; Suna, E. J. Org. Chem. 2021, 86, 7189–7202.

DOI: 10.1021/acs.joc.1c00545

Abstract

Non-enzymatic dynamic kinetic resolution (DKR) of secondary alcohols by enantioselective acylation using an isothiourea-derived HyperBTM catalyst and racemization of slowly reacting alcohol by Bäckvall’s ruthenium complex is reported. The DKR approach features high enantioselectivities (up to 99:1), employs easy-to-handle crystalline 4-nitrophenyl isobutyrate as the acylating reagent, and proceeds at room temperature and under an ambient atmosphere. The stereoinduction model featuring cation−π system interactions between the acylated HyperBTM catalyst and π electrons of an alcohol aryl subunit has been elaborated by DFT calculations.