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-a]­pyrrolo­[3,4-c]­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.