Stereoelectronic suppression and a remarkably low effective concentration for a cyclization to a benzo-fused five-membered ring

Abstract

The cyclization of o-chloromethylbenzylamine to dihydroisoindole has an effective concentration of 8.3 M(in CD₃OD at 21 °C); this very low value for a cyclization to a benzo-fused five-membered ring is ascribed to lessened conjugation in the transition state as compared to that of the model reaction, and is relevant to both the synthesis of rings and the application of effective concentrations in obtaining evidence of mechanism.