Protic guanidinium ionic liquid as a green and highly efficient catalyst for the synthesis of functionalized spirochromenes under solvent-free conditions
Résumé A simple and efficient method for the synthesis of functionalized spirochromenes is explained using protic guanidinium ionic liquid as a catalyst under solvent-free conditions at room temperature. This procedure is simple, clean, and excellent yields are obtained in short reaction times.
AbstractIsinglass, derivedfrom swim bladders of Caspian Sea fish and consisting predominantly of protein collagen, was found to be an effective, easily accessible heterogeneous biocatalyst for the synthesis of biologically important functionalized spirooxindoles and spiroacenaphthylenes in water. This facile and efficient one-pot, three-component synthesis route involving isatin or acenaphthenequinone
Gold(III) chloride (HAuCl4 center dot 3H(2)O) in PEG 400 was found to be an efficient catalytic system for the synthesis of biologically important functionalized spirochromene derivatives via one-pot three-component reaction of isatins/acenaphthoquinone, active methylene compounds and cyclic 1,3-diketones/4-hydroxycoumarin. A new catalytic system, recyclability of reaction medium, little reaction times and excellent yields with easy workup render this protocol more attractive and economically viable. (C) 2012 Elsevier B.V. All rights reserved.