Xu Ban, Yifan Fan, Tuan-Khoa Kha, Richmond Lee, Choon Wee Kee, Zhiyong Jiang and Choon-Hong Tan, CCS Chem. 2021, 3, 2192–2200
Abstract:
The stereoselective construction of vicinal all-carbon quaternary stereocenters has long been a formidable synthetic challenge. Direct asymmetric coupling of a tertiary carbon nucleophile with a tertiary carbon electrophile is the most straightforward approach, but it is sterically and energetically disfavoured. Herein, we describe a catalytic asymmetric substitution, where racemic tertiary bromides coupled directly with racemic secondary or tertiary carbanion, creating a series of congested C(sp3)-C(sp3) bonds, including isolated all-carbon quaternary stereocenters, vicinal tertiary/all-carbon quaternary stereocenters and vicinal all-carbon quaternary stereocenters. Using pentanidium as a catalyst, this double stereoconvergent process afforded substituted products in good enantioselectivities and diastereoselectivities.
Full text available at: https://www.chinesechemsoc.org/doi/10.31635/ccschem.021.202101013