PHOTO- AND THERMOINDUCED GENERATION OF 1,3-DIARYL CARBONYL YLIDES FROM 2,3-DIARYLOXIRANES. 1,3-DIPOLAR CYCLOADDITIONS TO DIPOLAROPHILES

Article abstract of DOI:10.1016/S0040-4020(01)92383-X

A group of symmetrically substituted 2,3-diaryloxiranes have been studied as photoprecursprs for carbonyl ylides.The stereochemistry of the adducts obtained upon interception of these 4n pi-transient systems with a variety of dipolarophiles provides information on the mode(s) of electrocyclic opening of the oxiranes to carbonyl ylides, as well as the mechanism of the 4n+2 cycloaddition process.The stereochemistry of the dipolarophiles is preserved in the cycloadducts, which is consistent with a concerted addition process; however, solvent effects, steric hindrance, and possibly secondary orbital overlap factors all may play a role in determining the product distribution.