Enantioselective biosynthesis of vicinal diamines enabled by synergistic photo/biocatalysis consisting of an ene-reductase and a green-light-excited organic dye

ABSTRACT

Vicinal diamines are key motifs widely-found in many pharmaceuticals and biologically active molecules. An appealing approach for synthesizing these molecules is the amination of enamines, but few examples have been explored. With the utilization of nitrogen-centered radicals (NCRs), here we present the development of a dual bio-/photo-catalytic system for achieving enantioselective hydroamination of enamides, which can give easy access to diverse enantioenriched vicinal diamines. These reactions progress efficiently under green light excitation and exhibit excellent enantioselectivities (up to >99% enantiomeric excess). Mechanistic studies uncovered the synergistic effect of the enzyme and the externally added organophotoredox catalyst Rhodamine B (RhB). This work demonstrates the effectiveness of photobiocatalysis to generate and control high-energy radical intermediates, addressing a long-standing challenge in chemical synthesis.