Reaction of 1,1-diphenyl-2-vinylcyclopropane with tetracyanoethylene, diene, diborane, and dibromocarbene. Formation of unusual adducts after rearrangements supporting a two-step process
Reaction of 1,1-diphenyl-2-vinylcyclopropane with 2,3,4,5-tetrachlorocyclopentadienone ethylene ketal proceeded smoothly to give a diene adduct quantitatively, whereas its reaction with tetracyanoethylene gave unexpected adducts after rearrangements. These results evidence that the latter donor-acceptor type cycloaddition proceeds via a zwitterionic intermediate.