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Desulfurization Strategy in the Construction of Azoles Possessing Additional Nitrogen, Oxygen or Sulfur using a Copper(I) Catalyst
Author(s) -
Guin Srimanta,
Rout Saroj Kumar,
Gogoi Anupal,
Nandi Shyamapada,
Ghara Krishna Kanta,
Patel Bhisma K.
Publication year - 2012
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201200408
Subject(s) - chemistry , copper , catalysis , nucleophile , intramolecular force , iodide , sulfur , copper oxide , flue gas desulfurization , catalytic cycle , combinatorial chemistry , regioselectivity , inorganic chemistry , organic chemistry
A tandem and convergent approach to various N‐, O‐, or S‐containing azoles has been developed by exploiting the thiophilic property of copper(I) iodide used in a catalytic quantity. The present protocol gives access to amino‐substituted tetrazoles, triazoles, oxadiazoles and thiadiazoles via oxidative desulfurization of their respective precursors followed by inter‐ or intramolecular attack of suitable nucleophiles. For aminotetrazoles and triazoles an excellent regioselectivity has been achieved through proper tuning of the pK a values of the parent amines attached to unsymmetrical thioureas. The method represents an autocatalytic process in which copper(I) iodide gets converted to copper(II) sulfide which in turn transforms to active copper(II) oxide that effectively carries forward the catalytic cycle. The fate of the copper catalyst has also been studied using scanning electron microscopic (SEM) and energy‐dispersive X‐ray spectroscopic (EDS) analyses which give an insight into the mechanism for this catalytic process.