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Greener Synthetic Alternatives to Heterocycles, Nanomaterials and Nanocomposites
Citation:
VARMA, R. S. Greener Synthetic Alternatives to Heterocycles, Nanomaterials and Nanocomposites. Presented at 6th International Microwave in Chemistry Conference, Cambridge, MA, May 12 - 16, 2008.
Impact/Purpose:
To inform the public.
Description:
Microwave (MW) expedited reaction of neat reactants or catalyzed by mineral support surfaces, such as alumina, silica, clay, or their ‘doped’ versions, for the rapid one-pot assembly of heterocyclic compounds from in situ generated reactive intermediates via enamines or using hypervalent iodine reagents will be described that can be adapted for parallel synthesis in multicomponent reactions. The eco-friendly nucleophilic substitution chemistry in water can be manipulated using microwaves to generate cyclic amines via double N-alkylation of primary amines or hydrazines by dihalides or tosylates. Greener protocols for the synthesis of pharmaceutically active heterocycles namely N-aryl azacycloalkanes, isoindoles, and dihydropyrazoles, 1,3,4-oxadiazoles, 1,3,4-thiadiazoles, 1,3-dioxanes, pyrazoles, hydrazones and 3,4-dihydropyrimidin-2(1H0-ones, catalyzed by basic water or polystyrene sulfonic acid (PSSA) in aqueous media or solid supported Nafio NR50 or (P4S10/Al2O3) under solvent-free conditions will be described.