A new application of N,N′-dibromo-N,N′-1,2-ethanediylbis(p- toluenesulfonamide) as selective and efficient reagent for the oxidation of various thiols to disulfides

Article abstract of DOI:10.1080/104265090517316

An efficient method for oxidation of thiol to their corresponding disulfides in high yields with N,N′-Dibromo-N,N′-1,2-ethanediyl bis (p-toluensulphonamide) in dichloromethane at room temperature is described. Copyright Taylor & Francis Inc.

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Phosphorus, Sulfur, and Silicon
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A New Application of
N,N ′-dibromo-N,N
′–1,2-ethanediylbis(p-
toluenesulfonamide) as
Selective and Efficient Reagent
for the Oxidation of Various
Thiols to Disulfides
Ardeshir Khazaei a & Amin Rostami a
a Department of Chemistry, Faculty of Science, Bu-
Ali Sina University, Hamedan, IR, Iran
Version of record first published: 21 Dec 2010.
To cite this article: Ardeshir Khazaei & Amin Rostami (2005): A New Application
of N,N ′-dibromo-N,N ′–1,2-ethanediylbis(p-toluenesulfonamide) as Selective and
Efficient Reagent for the Oxidation of Various Thiols to Disulfides, Phosphorus, Sulfur,
and Silicon and the Related Elements, 180:2, 555-557
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Phosphorus, Sulfur, and Silicon, 180:555–557, 2005
Copyright © Taylor & Francis Inc.
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/104265090517316
A New Application of N,Nꢀ-dibromo-N,Nꢀ–1,2-
ethanediylbis(p-toluenesulfonamide) as Selective
and Efficient Reagent for the Oxidation of Various
Thiols to Disulfides
Ardeshir Khazaei
Amin Rostami
Department of Chemistry, Faculty of Science, Bu-Ali Sina University,
Hamedan, IR, Iran
An efficient method for oxidation of thiol to their corresponding disulfides in
high yields with N,Nꢀ-Dibromo-N,Nꢀ–1,2-ethanediyl bis (p-toluensulphonamide)
in dichloromethane at room temperature is described.
Keywords BNBTS; Disulfide; Oxidation; Thiol
INTRODUCTION
Disulfides are an important compounds from both biological and syn-
thetic points of views.1,2 Disulfides are also important intermediates
with a great deal of application in organic synthesis.3–5 The trans-
formation of thiols to disulfides has been studied employing various
oxidants.6–9 However, some of these reagents suffer from one or more
of the following disadvantages: availability of the reagents, toxicity, te-
dious work-up, high cost, preparation, and stability of the reagent . As a
result, there is still a need for introducing readily available, safe, stable,
and in a cheap reagents for the oxidation of thiols to disulfides.
Extending our work on the use of N-halosolulfonamid, in organic
synthesis.10–14 We now report an efficient and convenient method for
the oxidative coupling of thiols to their corresponding disulfides by
using a new, cheap, and easily made reagent N,Nꢀ-Dibromo-N,Nꢀ–1,2-
ethanediylbis(p-toluenesulfonamide), [BNBTS] (2) that was prepared
Received June 4, 2004; in final form July 13, 2004.
We are thankful to the Bu-Ali Sina University Research Councils for partial support
of this work.
Address correspondence to Ardeshir Khazaei, Department of Chemistry, Faculty
of Science, Bu-Ali Sina University, PO Box 65174-4119, Hamedan, IR, Iran. E-mail:
a khazaei@basu.ac.ir
555

556
A. Khazaei and A. Rostami
FIGURE 1
from N,Nꢀ–1,2-ethanediylbis(p-toluenesulfonamide) [BNHTS] (1) (Fig-
ure 1).
Different kinds of thiols were subjected to oxidation reaction in the
presence of BNBTS in CH2Cl2 at room temperature (Scheme 1).
SCHEME 1
The results of this study are summarized in Table I. As shown in the
Table I, a variety of aliphatic (cyclic and acyclic), aromatic thiols are con-
verted into symmetrical disulfides with high yields. In case of aromatic
thiols bromination of aromatic ring was not observed; also selectivity of
the present method is evident by the oxidation of 2-mercaptoethanol
(entry 11) where only mercaptan functionality is converted to the
disulfides.
TABLE I Oxidation of Thiols to Disulfides with
BNBTS in Dichloromethane at Room Temperature
Entry
R
Time (h)
Mol ratio
Yield (%)
1
2
3
4
5
6
7
8
9
Ph
1.5
1.5
2
1.7
1.8
2.5
3
3
3
3.2
3.5
3.8
1
1
1
1
1
1
1
1
1
1
1
1
93
94
95
92
94
93
91
92
90
94
90
93
4-MeC6H4
4-ClC6H4
2-MeC6H4
2-Naphthyl
PhCH2
Cyclohexyl
n-Ethyl
n-Buthyl
10
11
12
n-Octyl
HOCH2CH2
HOOCCH2CH2

Disulfides
557
CONCLUSION
This article describes a facile synthesis of disulfides using BNBTS that
is cheap, stable, and an easily handled oxidizing agent in comparison
to most oxidants usually employed for this transformation. Also the
recovered starting martial (1) was rebrominated and used many times
without reducing the yield. The method offers several other advantages
including simplicity of the reaction conditions, application to alkyl and
aryl thiol, selectivity, and ease of isolation of the products.
EXPERIMENTAL
All products are known compounds and were characterized by com-
parison of their spectral data (1H- NMR and IR) and their physical
properties with those reported in the literature.
GENERAL PROCEDURE FOR OXIDATION OF THIOLS
To a solution of thiol (1 mmol) in dichloromethane (10 mL) was added
BNBTS (1 mmol) and the mixture was stirred vigorously and magnet-
ically at room temperature for the indicated time according to Table I.
The reaction was monitored by thin layer chromatography (TLC). After
completion of the reaction, the insoluble sulfonamide (1) was removed
by filtration and washed with dichloromethan (10 mL). Evaporation of
the solvent followed by recrystallization or chromatography on silica
gel afforded pure disulfide in 90–95% yields (Table I).
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