The 7-Cycloheptatrienylmethyl/7-Norcaradienylmethyl Cation System

Reaction of 7-carbomethoxycycloheptatriene with either BCl 3 or BBr 3 gave a 1:1 complex in which the Lewis acid was complexed to the carbonyl oxygen. The low temperature p.m.r. and u.v. spectra of these zwitterions indicated that they existed almost entirely in the norcaradiene forms 10 and 14, respectively. In contrast, reaction of N,N-dimethyl-1,3,5-cycloheptatriene-7-carboxamide with BCl 3 was found to result in the formation of a mixture …