Lewis acid catalyzed reactions of methylenecyclopropylcarbinols with acetals for the construction of 3-oxabicyclo[3.1.0]hexane derivatives

Reactions of methylenecyclopropylcarbinols 1 with acetals 2 in the presence of Lewis acid Sc(OPf)3 produce the ring-closure products 3-oxabicyclo[3.1.0]hexane in moderate to high total yields along with the products in trans-configuration as the sole or major one. The plausible reaction mechanism has been discussed, which is based on the Prins-type reaction mechanism.