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ABSTRACT: An operationally simple and entirely green protocol for heteropoly acid catalyst conjugate addition of indoles and pyrrole to unsaturated carbonyl compounds and nitro-alkene in water was investigated. It is important that the products arising from 1,2-addition were not observed under the reaction conditions. Pyrroles also readily underwent Michael addition at Α-positions under the same reaction conditions. Indole and many of its derivatives are present in many substances commonly found in nature. Micheal addition reactions are performed in organic solvents with the reactions in water are relatively scarce. The Michael addition between indole and methyl vinyl ketone in the presence of catalysts proceed efficiently furnishing moderate to excellent yields of the desired products. It was observed that a highly efficient and entirely green protocol for Friedel-Crafts alkylation of indole and pyrrole with several electron-deficient olefins in water has excellent yielding.
Organic & Biomolecular Chemistry 04/2007; 4(23):4275-7. DOI:10.1039/b610263h · 3.56 Impact Factor