Visible-Light-Promoted Cascade Cyclization of 3-Ethynyl-[1,1-biphenyl]-2-Carbonitriles with Unsaturated -Bromocarbonyls

A visible-light-promoted cascade cyclization of 3-ethynyl-[1,1 '-biphenyl]-2-carbonitriles with unsaturated alpha-bromocarbonyls for the synthesis of tetrahydrobenzo[mn]cyclopenta[b]acridines is described. Three C(sp(3))-C(sp(2)) bonds, one C(sp(2))-N bond, and three cycles can be formed in a single reaction through the addition of a C-centered radical to the carbon-carbon triple bond and three radical cyclizations. This reaction features mild conditions, wide substrate scope, and high bond-forming efficiency.