Related Experiment Video
Updated: Nov 11, 2025

Synthesis of pH Dependent Pyrazole, Imidazole, and Isoindolone Dipyrrinone Fluorophores using a Claisen-Schmidt Condensation Approach
Published on: June 10, 2021
A Phosphine-Mediated Dearomative Skeletal Rearrangement of Dianiline Squaraine Dyes
Emily P Bacher1, Kevin J Koh1, Antonio J Lepore1
1Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556, United States.
Abstract:
A phosphorus(III)-mediated dearomatization of ortho-substituted dianiline squaraine dyes results in an unusual skeletal rearrangement to provide exotic, highly conjugated benzofuranone and oxindole scaffolds bearing a C3 side chain comprised of a linear conflagration of an enol, a phosphorus ylide, and 2,4-disubstituted aniline. Employing experimental and computational analysis, a mechanistic evaluation revealed a striking dependence on the acidity of the aniline ortho substituent. Notably, the rearrangement adducts underwent rapid and complete reversion to the parent squaraine in the presence of a Brønsted acid.
Related Concept Videos
[3,3] Sigmatropic Rearrangement of 1,5-Dienes: Cope Rearrangement
Diazonium Group Substitution: –OH and –H
[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
Nucleophilic Aromatic Substitution of Aryldiazonium Salts: Aromatic SN1
In the Sandmeyer reaction, for example, the diazonio group is replaced by a chloro, bromo,...
Preparation of 1° Amines: Hofmann and Curtius Rearrangement Overview
Diazonium Group Substitution with Halogens and Cyanide: Sandmeyer and Schiemann Reactions

