Photoredox catalyzed cascade CF3 addition/chemodivergent annulations of ortho-alkenyl aryl ureas

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.

Visible-light-mediated selenocyclization of o-vinylanilides with diselenides

Herein, we describe a visible-light-mediated selenocyclization of o-vinylanilides with diselenides, which provides a mild and effective method for the synthesis of selenylated 4H-3,1-benzoxazines. This reaction proceeds under metal-free conditions, without the need for a chemical oxidant or a controlled O2 atmosphere and shows a broad substrate scope with yields of up to 98%. Additionally, the process is easily scalable to the gram scale.

Oxo-Sulfonylation of 1,7-Enynes via a Multicomponent Oxidative Radical Polar Crossover Approach

Diastereoselective synthesis of trans-3,4-difunctionalized tetrahydroquinoline and chromane derivatives via the oxo-sulfonylation of 1,7-enynes is demonstrated. The reaction involves a three-component oxidative radical polar crossover (ORPC) approach wherein a vinyl carbocation intermediate undergoes nucleophilic substitution to afford the corresponding keto functional group. Deprotection of the N-Ts group, gram-scale synthesis, and other synthetic applications were illustrated. Control experiments and mechanistic studies show that water acts as the nucleophile in this reaction.

Photomediated Tandem Sulfonyl Addition-Chemoselective N-Cyclization of o-Alkenyl Aryl Ureas: Direct Assembly of Functionalized Dihydroquinazolinones

Photoredox-mediated tandem addition-chemoselective cyclization of o-alkenyl aryl ureas is reported for the synthesis of sulfonyl and activated alkyl-decorated dihydroquinazolinones. By a careful choice of o-alkenyl aryl urea starting materials, we achieved chemoselective N-cyclization in the presence of more reactive amidic oxygen. We have demonstrated the scope of the methodology with a variety of sulfonyl chlorides and activated alkyl halides. Finally, large-scale synthesis of sulfonyl-substituted dihydroquinazolinone showcases the synthetic utility of the methodology.