Triarylmethanes and their Medium‐Ring Analogues by Unactivated Truce–Smiles Rearrangement of Benzanilides

Abstract

Intramolecular nucleophilic aromatic substitution (Truce-Smiles rearrangement) of the anions of 2-benzyl benzanilides leads to triarylmethanes in an operationally simple manner. The reaction succeeds even without electronic activation of the ring that plays the role of electrophile in the S N Ar reaction, being accelerated instead by the preferred conformation imposed by the tertiary amide tether. The amide substituent of the product may be removed or transformed into alternative functional groups. A ring-expanding variant (n to n + 4) of the reaction provided a route to doubly benzo-fused medium ring lactams of 10 or 11 members. Hammett analysis returned a 1 value consistent with the operation of a partially concerted reaction mechanism.