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 9 using a three-component imino Diels-Alder cycloaddition between trans-isoeugenol 4 or trans-anethole 5, anilines 6, and benzaldehyde 7 in the presence of BF3·OEt2 in PEG-400 has been developed. Also, BF3·OEt2-catalyzed formal [3+2] cycloaddition reaction of trans-isoeugenol or trans-anethole with 1,4-benzoquinone 8 in PEG-400 to give dihydrobenzo[b]furan derivatives 10 has been described.