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Highly diastereoselective synthesis of tetrahydrofurans via Lewis acid-catalyzed cyclopropane/aldehyde cycloadditions.

A one-step procedure for the preparation of 2,5-disubstituted tetrahydrofurans from donor-acceptor cyclopropanes and aldehydes has been developed. In the presence of a catalytic amount of Sn(OTf)(2), cyclopropanes bearing an aryl or conjugated donor substituent vicinal to a malonyl diester group undergo cycloadditions with diverse conjugated aldehydes furnishing tetrahydrofurans with high cis diastereoselectivity. This method is useful for the preparation of regiodefined tetrahydrofurans.