Brønsted acid cocatalysis in copper(I)-photocatalyzed α-amino C−H bond functionalization

We have exploited a bis(1,10-phenanthroline)copper(I) visible light photocatalyst (VLP), [Cu(dap)₂]⁺, to effect the direct α-C–H functionalization of amines. To our knowledge, this represents the first example of the oxidation of amines that are ultimately incorporated into synthetic targets by a copper(I) VLP. We have utilized this approach to rapidly prepare unprecedented octahydroisoquinolino[2,1-<i>a</i>]pyrrolo[3,4-<i>c</i>]quinoline frameworks and exploited this process to synthesize a novel aglycone analogue of the natural product incargranine B. Most significantly, our studies suggest that the presence of trifluoroacetic acid (TFA) is crucial in mediating the aerobic oxidative quenching of a putative photoexcited copper(I) species involved in the catalytic cycle.