Racemicα-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...Racemicα-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-boundα-chloro imidazol-2-yl-ketone,followed by chloride fragmentation of theα-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.展开更多
基金supported by the Deutsche Forschungsgemeinschaft(ME 1805/17-1)
文摘Racemicα-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-boundα-chloro imidazol-2-yl-ketone,followed by chloride fragmentation of theα-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.
