Anion effect on enantioselective oxidative NHC catalysis: highly efficient kinetic resolution of tertiary alcohols and beyond. Issue 2 (7th December 2022)

• Record Type: Journal Article
• Authors: Hu, Dan; Poh, Si Bei; Liu, Feipeng; Tu, Zhifeng; Wang, Xia; Lu, Shenci; Zhao, Yu
• Is Part Of: Organic chemistry frontiers. Volume 10:Issue 2(2023)
• Page Start: 416
• Page End: 421
• Publication Date: 2022-12-07
• Subjects: Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1039/d2qo01506d
• Languages: English
• ISSNs: 2052-4110

Abstract

Abstract : The effect of the counter-anion in the azolium pre-catalyst on enantio-control in oxidative NHC catalysis is demonstrated systematically for the first time in acylative kinetic resolution of oxindole-derived tertiary alcohols. Abstract : The effect of the counter-anion on enantio-control in oxidative NHC catalysis is demonstrated systematically for the first time. For kinetic resolution of oxindole-derived tertiary alcohols through NHC-catalyzed esterification, the identity of anions, either in the form of an additive or as the counter-anion in the azolium pre-catalyst, showed a significant effect on the enantioselectivity of the catalytic system. With the suitable choice of anions, highly efficient kinetic resolution (with k rel between 30 and >200) was achieved for a wide range of oxindole-derived tertiary alcohols bearing alkyl, aryl and functionalized substituents. The anion effect on other oxidative NHC-catalyzed processes such as formal cycloaddition is also demonstrated.