An efficient photoredox‐catalyzed halo‐trifluoromethylation reaction of 1,7‐enynes has been developed under mild conditions. This photocatalytic protocol provides an efficient and functional strategy leading to CF3− and halogen‐containing 3,4‐dihydroquinolin‐2(1H)‐ones from a wide range of 1,7‐enynes through two different radical pathways. The reaction mechanism was proposed based on the control experiments.magnified image

A catalytic domino spirocyclization of 1,7-enynes with simple cycloalkanes and cyclo-1,3-dicarbonyls has been established via multiple C-C bond formations from alkynyl/alkenyl functions and dual α,α-C(sp(3))-H abstraction/insertion. The reaction involves addition, 6-exo-dig cyclization and radical coupling sequences under convenient catalytic conditions and provides a concise access to spiro cyclopenta[c]quinolines in good to excellent yields.

A new cascade three-component halosulfonylation of 1,7-enynes for efficient synthesis of densely functionalized 3,4-dihydroquinolin-2(1H)-ones has been established from readily accessible arylsulfonyl hydrazides and NIS (or NBS). The reaction pathway involves in situ-generated sulfonyl radical-triggered α,β-conjugated addition/6-exo-dig cyclization/radical coupling sequence, resulting in continuous multiple bond-forming events including C–S, C-C and C-I (or C-Br) bonds to rapidly build up molecular complexity.