New insight on the mechanism of 2-oxabicyclobutane fragmentation. A high-level ab initio study

High-level quantum chemical studies have been carried out to explain the un usual chemical reactivity of 2-oxabicyclobutane for the process of its frag mentation to acrolein. The predicted activation energy values for unimolecu lar and acid-catalysed fragmentation of OBB are high enough to rule out OBB intermediacy in the various thermal, photochemical and chemical reactions. These findings suggest that 2-oxabicyclobutane is so highly stable that th ere should be another mechanism of above mentioned reactions which leads to the formation of aldehydes and ketones. (C) 2001 Elsevier Science Ltd. All rights reserved.