Bio-Inspired Catalytic Imine Reduction by Rhodium Complexes with Tethered Hantzsch Pyrldlnlum Groups: Evidence for Direct Hydride Transfer from Dihydropyridine to Metal-Activated Substrate

摘要

Herein, we report a conceptually new approach to the catalytic reduction of unsaturated substrates, demonstrated for imine hydrogenation, based on mimicry of biological processes in which hydride is directly transferred from dihydronicotinamide adenine dinucleotide (phosphate) (NAD(P)H) cofactor to an enzyme-activated substrate. NAD(P)H is Nature's hydride carrier. In many (dehydrogenase enzymes that catalyze direct hydride transfer to/ from NAD(P)~+/NAD(P)H, the substrate is polarized and thus activated by binding to a metal ion. Classic examples are alcohol dehydrogenases (Zn~(2+) active site) and acetohydroxy acid isomeroreductase hydrogenases (with an (Mg~(2+))2 or (Mn~(2+))2 active site).