Lewis acid-catalyzed Prins-type reactions of methylenecyclopropylcarbinols with aldehydes and aldimines

Lewis acid-catalyzed Prins-type reactions of methylenecyclopropylcarbinols with aldehydes and N-tosyl aldimines proceeded smoothly to give the corresponding 3-oxa-bicyclo[3.1.0] hexane units via 5-exo cyclization in good to high total yields (both 3 and 3′ included a pair of diastereoisomers, see the Letter for details).