Enantioconvergent photoredox radical-radical coupling catalyzed by a chiral-at-rhodium complex

• 来源期刊: 中国科学:化学（英文版）
• 年，卷（期）: 2019,（11）
• 页码范围: 1512-1518
• 页数: 7页
• 语种: 英文

摘要

Racemic α-chloro imidazol-2-yl-ketones undergo an enantioconvergent photoactivated C-C bond formation with N-aryl glycines catalyzed by a single bis-cyclometalated chiral-at-rhodium catalyst in yields of up to 80％ and up to 98％ enantiomeric excess (ee).Control experiments support a mechanism which is initiated by a single electron transfer from N-aryl glycinate to the photochemically excited rhodium-bound α-chloro imidazol-2-yl-ketone,followed by chloride fragmentation of the α-chloroketone,decarboxylation of the glycinate,and a subsequent highly stereocontrolled radical-radical coupling.This work showcases the ability of the chiral rhodium catalyst to serve a dual function as chiral Lewis acid and at the same time as the photoredox active species upon substrate binding.