REACTIONS OF CARBENES WITH BICYCLOBUTANES AND QUADRICYCLANE CYCLOADDITIONS WITH TWO ? BONDS

Article abstract of DOI:10.1016/S0040-4020(01)96386-0

Dicarcomethoxycarbene and dichlorocarbene add to 1,2,2-trimethylbicyclo<1.1.0>butane in such a fashion as to suggest a concerted addition in which the central and side bonds are cleaved simultaneously.MNDO calculations support such a pathway and suggest that endo attack on the bicyclobutane is preferred to exo.Reaction of the same two carbenes with quadricyclane gives substituted derivatives of the exo-tricyclo<3.2.1.0^2,4>oct-6-ene system.Although these products rearrange further under the conditions of reaction and/or analysis, they can be shown to be primary products.It is suggested that quadricyclane reacts with carbenes in a concerted fashion.