Browsing by Author "Kumari, M."

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    Efficient Synthesis of Novel Biginelli and Hantzsch Products Sourced from Biorenewable Furfurals Using Gluconic Acid Aqueous Solution as the Green Organocatalyst
    (American Chemical Society, 2023) Anchan, H.N.; Naik C, P.; Bhat, N.S.; Kumari, M.; Dutta, S.
    The Biginelli reaction provides 3,4-dihydropyrimidin-2(1H)-ones (DHPMs), whereas the Hantzsch reaction leads to 1,4-dihydropyridines (DHPs) by the one-pot, multicomponent, and operationally simple transformations starting from readily available starting materials. DHPMs and DHPs are well-established heterocyclic moieties in the synthetic organic chemistry literature and have pronounced pharmacological activities. This work reports the synthesis of novel DHPMs and DHPs from carbohydrate-derived 5-substituted-2-furaldehydes by employing gluconic acid aqueous solution (GAAS) as an efficient, inexpensive, and eco-friendly catalyst. The use of urea (or thiourea) as the reagent led to DHPMs, whereas ammonium acetate produced DHPs, selectively, keeping the other two starting materials (i.e., furfurals and ethyl acetoacetate) and the reaction parameters unaltered. Using the general synthetic protocol under optimized reaction conditions (60 °C, 3-6 h, 25 mol % GAAS cat.), all the DHPM and DHP derivatives were obtained in good to excellent isolated yields. © 2023 The Authors. Published by American Chemical Society
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    Synthesis of novel Biginelli and Hantzsch products from biorenewable furfurals using 1,4-diazabicyclo[2.2.2]octanium diacetate as a Brønsted acidic ionic liquid catalyst
    (John Wiley and Sons Inc, 2023) Bhat, N.S.; Kumari, M.; Naik C, P.; Mal, S.S.; Dutta, S.
    3,4-Dihydropyrimidin-2(1H)-ones (DHPMs) and 1,4-dihydropyridines (DHPs) are well-established classes of heterocyclic compounds with remarkable biological properties. Various protonated organic amines were screened as Brønsted acidic ionic liquid catalysts under the Biginelli and Hantzsch reaction conditions for synthesizing novel DHPMs and DHPs, respectively, starting from biorenewable furfurals. 1,4-Diazabicyclo[2.2.2]octanium diacetate (DABCO-DA) was found as an efficient catalyst for the organic solvent-free synthesis of novel DHPMs and DHPs in excellent (>85 %) isolated yields. The process parameters (e. g., temperature, molar ratio of reagents, duration, and loading of acid catalyst) were optimized, and a general synthetic protocol for synthesizing DHPMs and DHPs from 5-substituted-2-furaldehydes has been developed. The DABCO-DA catalyst was successfully recovered from the reaction mixture and reused for four consecutive cycles. © 2023 Wiley-VCH Verlag GmbH.