Reaction of 7,7-diphenyl-6-oxabicyclo[3.2.0]hept-1-ene with ROH; controlling factors on the regioselectivity in the nucleophilic addition reaction

ROH-induced decomposition of the strained 7,7-diphenyl-6-oxabicyclo[3.2.0]hept-1-ene was investigated in detail. The selective formation of the endo double-bonded alkene was observed for the reaction with H2O or MeOH. Alternatively, the reaction with hexafluoro-2-propanol or acetic acid exclusively afforded the exo double-bonded alkene . The dramatic ROH effect on the product distribution is rationalized in this study. Strain energy (SE=41.3 kcal/mol) of 6-oxabicyclo[3.2.0]hept-1-ene was calculated at RHF/6-31G∗ level of theory.