Photomediated Radical Cascade Addition–Cyclization of N-Butenoyl Tetrahydroquinolines: Accessing Functionalized Julolidines

Herein, we describe the photomediated radical cascade addition-cyclization of N-butenoyl tetrahydroquinolines to access various functionalized julolidine-5-one. The scope of the methodology was illustrated with several sulfonyl chlorides and tetrahydroquinolines. Other radical precursors, such as trifluoromethyl, bromoacetonitrile, bromoacetates, etc., also worked efficiently, demonstrating the broad utility of the method. Finally, large-scale synthesis of sulfonyl-substituted julolidine-5-one and downstream conversions of the synthesized julolidine derivatives were carried out to illustrate the synthetic utility of the methodology.