Neighboring group effect of five-membered heteroaromatic rings for π-facial selectivity in the reactions of fused isopropylidenenorbornene systems with electrophilic reagents

The electrophilic reactions of novel isopropylidenenorbornadienes and isopropylidenenorbornenes fused with a furan, pyrrole, thiophene, and pyrazole ring with 1,2,4-triazole-3,5-(4H)-dione, m-chloroperbenzoic acid, dichlorocarbene, and N-bromosuccinimide (NBS) indicated that the neighboring group effect of the five-membered heteroaromatic rings was, unexpectedly, almost similar to that of a benzene ring except for the reaction with NBS.