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Base Promoted Tandem Cyclization of o ‐Phenylenediamine with Ninhydrin‐phenol Adducts: An Unprecedented Route to Phenol Appended Isoindolo[2,1‐ a ]quinoxaline Fluorophore
Author(s) -
Das Suven,
Maity Suvendu,
Ghosh Prasanta,
Paul Bijan K.,
Dutta Arpita
Publication year - 2019
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201804069
Subject(s) - ninhydrin , chemistry , quinoxaline , fluorophore , adduct , phenol , fluorescence , base (topology) , photochemistry , medicinal chemistry , polymer chemistry , combinatorial chemistry , organic chemistry , mathematical analysis , biochemistry , physics , mathematics , amino acid , quantum mechanics
Synthesis of fluorescent molecules has drawn considerable attention due to their potential applications in life and material sciences. Here we report a metal‐free approach to a new class of fluorophore, namely, 6‐(2‐hydroxyaryl)isoindolo[2,1‐ a ]quinoxalin‐11(5 H )‐ones exploiting ninhydrin ring system via base promoted tandem cyclization. The readily obtainable phenolic adducts of ninhydrin undergoes smooth reaction with o ‐phenylenediamine in refluxing ethylene glycol/Et 3 N via breaking of C−C bond, N‐insertion, followed by heterocyclization to furnish the fully unsaturated isoindoloquinoxaline framework. Structures of the products are in good agreement with their IR, 1 H NMR, 13 C NMR, and mass spectral data. The photophysical properties of the synthesized compounds were studied by UV‐vis absorption and fluorescence spectroscopic techniques under ambient conditions, and the results reveal an interesting property of large Stokes shift.