Browsing by Author "Paul, Avijit K."

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    DABCO Mediated Sulfur Activation-Intramolecular De-Nitration Strategy for the Synthesis of Novel Dihydrothiochromeno[4,3-c]pyrazoles
    (John Wiley and Sons Inc, 2023-07-24T00:00:00) Deepika; Paul, Avijit K.; Malakar, Chandi C.; Bansal, Ajay; Singh, Virender
    A facile and highly efficient metal-free approach has been unfolded for the synthesis of novel dihydrothiochromeno[4,3-c]pyrazoles using elemental sulfur as a powerful sulfurating reagent. This method includes sp2 C?H functionalization followed by sp2 C?NO2 group displacement using elemental sulfur as an odourless sulfur source activated by DABCO in DMSO. Using the developed synthetic strategy, a library of 29 novel dihydrothiochromeno[4,3-c]pyrazoles, incorporating two pharmacologically important scaffolds has been synthesized in 52�76% yield with a broad substrate scope. A sensible mechanistic proposal has been projected based on control experiments. � 2023 Wiley-VCH GmbH.
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    KI-assisted Sulfur Activation/Insertion/Denitration Strategy towards Dual C?S Bond Formation for One-pot Synthesis of ?-Carboline-tethered 2-Acylbenzothiophenes
    (John Wiley and Sons Inc, 2021-12-13T00:00:00) Singh, Manpreet; Jamra., Rahul; Paul, Avijit K.; Malakar, Chandi C.; Singh, Virender
    A simple and efficient KI promoted sulfur activation-insertion/de-nitration strategy has been developed for the synthesis of ?-carboline C1 tethered 2-acylbenzothiophenes via one-pot assembly of 1-acetyl ?-carbolines (an alkaloid based scaffold), 2-nirobenzaldehydes and elemental sulfur. This expeditious reaction proceeds through the formation of ?-carboline linked nitro-chalcones followed by embodiment of elemental sulfur to generate the multifunctional ?-carboline linked benzothiophene derivatives. The highlighted features of this efficient methodology are transition metal-free conditions, use of inexpensive and non-toxic catalyst, easy procedure, short reaction time, and broad substrate scope with good yields. The scope of this protocol has been extended for the synthesis of a range of novel compounds with significant diversity. � 2021 Wiley-VCH GmbH