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Microwave-Assisted Rapid Access to Bio-active Heterocycles: Synthesis of 1,3,4-Oxadiazoles, 1,3,4-Thiadiazoles, 1,3-Dioxanes, Pyrazoles, Hydrazones and 3,4-Dihydropyrimidin-2(1H)-ones under Benign Conditions
Citation:
Polshettiware, V. AND R. S. VARMA. Microwave-Assisted Rapid Access to Bio-active Heterocycles: Synthesis of 1,3,4-Oxadiazoles, 1,3,4-Thiadiazoles, 1,3-Dioxanes, Pyrazoles, Hydrazones and 3,4-Dihydropyrimidin-2(1H)-ones under Benign Conditions. Presented at Select Biosciences Conference on Miscrowave-Assisted Organic Synthesis (MAOS), San Francisco, CA, October 03 - 04, 2007.
Impact/Purpose:
To inform the public.
Description:
Green chemistry is a rapidly developing new field that provides us a proactive avenue for the sustainable development of future science and technologies.1 It emphasis the use of highly efficient and environmental benign synthetic protocols to deliver bio-active heterocycles, accelerating lead optimization processes in drug discovery, with minimal environmental impact.2 Environmentally benign protocols have been developed for the synthesis of various pharmaceutically active heterocycles namely 1,3,4-oxadiazoles, 1,3,4-thiadiazoles, 1,3-dioxanes, pyrazoles, hydrazones and 3,4-dihydropyrimidin-2(1H)-ones, which proceed under the influence of microwave irradiation and using eco-friendly conditions. These greener protocols were catalyzed efficiently by solid supported Nafion®NR50,3 phosphorus pentasulfide on alumina (P4S10/Al2O3) under solvent-free conditions3 and polystyrene sulfonic acid (PSSA) in aqueous media,4-6 providing excellent yields.