Browsing by Author "Singh, Jujhar"

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    Organic Photoredox Catalyzed Direct Hydroamination of Ynamides with Azoles
    (Wiley, 2022-03-15) Wang, Ban; Mccabe, Gavin E.; Parrish, Mitchell J.; Singh, Jujhar; Zeller, Matthias; Deng, Yongming; Chemistry and Chemical Biology, School of Science
    Disclosed herein is a photoinduced selective hydroamination of ynamides with nitrogen heteroaromatic nucleophiles. By using an organocatalytic photoredox system, a direct method to construct a diverse of (Z)-α-azole enamides from ynamides and pyrazoles, as well as triazoles, benzotriazoles, indazoles, and tetrazoles, is developed, thus providing a photocatalytically synthetic route to heterocyclic motifs common in medicinal agents. Based on the mechanistic studies, the hydroamination is postulated to operate via a mechanism in which the single-electron oxidation of ynamide and the intermediacy of an alkyne radical cation, is responsible for the observed reactivity.
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    Photoredox-Catalyzed Divergent Radical Cascade Annulations of 1,6-Enynes via Pyridine N-Oxide-Promoted Vinyl Radical Generation
    (American Chemical Society, 2023) Wang, Ban; Singh, Jujhar; Deng, Yongming; Chemistry and Chemical Biology, School of Science
    The divergent organophotoredox-catalyzed radical cascade annulation reactions of 1,6-enynes were developed. A series of cyclopropane-fused hetero- and carbo-bicyclic, tricyclic, and spiro-tetracyclic compounds were facilely synthesized from a broad scope of 1,6-enynes and 2,6-lutidine N-oxide under mild and metal-free conditions with blue light-emitting diode light irradiation. The cascade annulation reaction occurs with the intermediacy of a β-oxyvinyl radical, which is produced from photocatalytically generated pyridine N-oxy radical addition to the carbon-carbon triple bond.