Rhodium catalysts with cofactor mimics for the biomimetic reduction of C
N bonds†
Abstract
A strategy based on the cooperation between metal and bonded cofactor mimics was applied to the transfer hydrogenation of CN bonds. We designed and synthesized a rhodium complex containing a 1,3-dimethylbenzoimidazole moiety, which could transfer hydride from a rhodium center to imine substrates in a biomimetic way. Under both transfer hydrogenation and reductive amination reaction conditions, the catalyst exhibited good selectivity towards C
N bonds. With the catalyst, 34 imines were transfer hydrogenated to corresponding amines and a key intermediate of retigabine was prepared via reductive amination in a greener way. According to the NMR observations and isotope experiments, a plausible mechanism for this biomimetic reduction of C
N bonds were proposed.