PEG-400 as green reaction medium for Lewis acid-promoted cycloaddition reactions with isoeugenol and anethole

A simple and efficient one-pot method for the synthesis of new 2,4-diaryl-1,2,3,4-tetrahydroquinolines using a three-component imino Diels-Alder cycloaddition between trans-isoeugenol or trans-anethole, anilines, and benzaldehyde in the presence of BF3 center dot OEt2 in PEG-400, a green and reusable solvent, has been developed. Also, BF3 center dot OEt2-catalyzed formal [3+2] cycloaddition reaction of tralls-isoeugenol or trans-anethole with 1,4-benzoquinone in PEG-400 to give dihydrobenzo[b]furan derivatives has been described. (C) 2008 Elsevier Ltd. All rights reserved.