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 SNAr 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 ρ value consistent with the operation of a partially concerted reaction mechanism.
Highlights
Intramolecular nucleophilic aromatic substitution (Truce–Smiles rearrangement) of the anions of 2-benzyl benzanilides leads to triarylmethanes in an operationally simple manner
Classical Truce–Smiles rearrangements proceed by 1,4- or 1,5-N or O to C intramolecular SNAr of electron-deficient aryl rings, but in our conformationally accelerated variant, much greater substrate generality is possible because no electronic activation is required.[20, 21]
Our proposed mechanism for the rearrangement that leads to the triarylmethane products starts with deprotonation of the 2-benzylbenzamide 1 by KHMDS (Scheme 6 a)
Summary
Intramolecular nucleophilic aromatic substitution (Truce–Smiles rearrangement) of the anions of 2-benzyl benzanilides leads to triarylmethanes in an operationally simple manner. E) This work: synthesis of triarylmethanes by conformationally accelerated intramolecular SNAr (Truce–Smiles) rearrangement.
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