Copper‐Catalyzed Enantioconvergent Cross‐Coupling of Racemic Alkyl Bromides with Azole C(sp<sup>2</sup>)−H Bonds
Xiaolong Su, Ye Liu, Ji‐Jun Chen, Xiaodong Liu, Xiaodong Liu, Shengpeng Jiang, Fuli Wang, Lin Liu, Chang‐Jiang Yang, Xiaoyong Chang, Zhong‐Liang Li, Qiang‐Shuai Gu, Xin‐Yuan Liu, Xin‐Yuan Liu
Abstract
Abstract The development of enantioconvergent cross‐coupling of racemic alkyl halides directly with heteroarene C(sp 2 )−H bonds has been impeded by the use of a base at elevated temperature that leads to racemization. We herein report a copper(I)/cinchona‐alkaloid‐derived N , N , P ‐ligand catalytic system that enables oxidative addition with racemic alkyl bromides under mild conditions. Thus, coupling with azole C(sp 2 )−H bonds has been achieved in high enantioselectivity, affording a number of potentially useful α‐chiral alkylated azoles, such as 1,3,4‐oxadiazoles, oxazoles, and benzo[ d ]oxazoles as well as 1,3,4‐triazoles, for drug discovery. Mechanistic experiments indicated facile deprotonation of an azole C(sp 2 )−H bond and the involvement of alkyl radical species under the reaction conditions.