3510
A. Akdag et al. / Tetrahedron Letters 47 (2006) 3509–3510
Table 1. Thiols used in this experiment and the yield of conversion to
disulfides
Company. The authors thank Dr. J. F. Williams for
helpful discussions during the course of this work.
Thiol
Isolated yield (%)
a
b
c
d
e
f
g
h
Ethanethiol
Butanethiol
85
81
91
86
60
90
93
92
References and notes
2-Mercaptoethanol
2-Propanethiol
2-Methyl-2-propanethiola
Thiophenol
4-Methoxythiophenol
Benzylthiol
1. (a) Organosulfur Chemistry Synthetic Aspects; Page, P., Ed.;
Academic Press: San Diego, 1995; (b) Organic Sulfur
Chemistry: Structure and Mechanism; Oae, S., Ed.; CRC:
Boca Raton, FL, 1991.
2. Vogel, A. I. Vogel’s Textbook of Practical Organic Chem-
istry; Longman Scientific & Technical; Wiley: New York,
1989.
a Only 50% conversion was observed by NMR even after 24 h.
3. Some examples are: (a) Iranpoor, N.; Mohajer, D.; Reza-
eifard, A.-R. Tetrahedron Lett. 2004, 45, 3811–3815; (b)
Lazzaro, F.; Crucianelli, M.; De Angelis, F.; Neri, V.;
Saladino, R. Tetrahedron Lett. 2004, 45, 9237–9240; (c)
Freeman, F.; Angeletakis, C. N. J. Am. Chem. Soc. 1983,
105, 4039–4049.
as formation of disulfide bonds and the prior
literature.4g
Different types of thiols were employed in this study:
primary, secondary, tertiary, phenylic, and benzylic
thiols. Except for tert-butyl thiol, excellent conversion
of thiols to disulfides has been observed. The low yield
using tert-butyl thiol may be due to the low acidity of
the tert-butyl thiol, or to steric hindrance caused by
the bulky tert-butyl group.8 The reaction products were
analyzed with 1H and 13C NMR spectroscopy (Table 1).
All of the spectra are in excellent agreement with the
literature9.
4. Some examples: (a) Khazaei, A.; Zolfigol, M. A.; Rostami,
A. Synthesis 2004, 2959–2961; (b) Joshi, A. V.; Bhusare, S.;
Baidossi, M.; Qafisheh, N.; Sasson, Y. Tetrahedron Lett.
2005, 46, 3583–3585; (c) Ali, M. H.; McDermott, M.
Tetrahedron Lett. 2002, 43, 6271–6273; (d) Patel, S.;
Mishra, B. K. Tetrahedron Lett. 2004, 45, 1371–1372; (e)
Leino, R.; Lo¨nnqvist, J.-E. Tetrahedron Lett. 2004, 45,
8489–8491; (f) Laszlo, P.; Delaude, L. J. Org. Chem. 1996,
61, 6360–6370; (g) Peskin, A. V.; Winterbourn, C. C. Free
Radical Biol. Med. 2001, 30, 572–579.
5. (a) Sun, G.; Wheatley, W. B.; Worley, S. D. Ind. Eng.
Chem. Res. 1994, 33, 168–170; (b) Chen, Y.; Worley, S. D.;
Kim, J.; Wei, C.-I.; Chen, T.-Y.; Santiago, J. I.; Williams, J.
F.; Sun, G. Ind. Eng. Chem. Res. 2003, 42, 280–284; (c)
Chen, Y.; Worley, S. D.; Kim, J.; Wei, C.-I.; Chen, T.-Y.;
Suess, J.; Kawai, H.; Williams, J. F. Ind. Eng. Chem. Res.
2003, 42, 5715–5720; (d) Sun, G.; Worley, S. D. Chem.
Oxid. 1997, 134–144.
6. The following general oxidation procedure was applied to
all thiols presented in Table 1. To a mixture of monochloro
polystryrene hydantoin beads (3 g) (obtained from Halo-
Source Company) in water (50 mL) was added a thiol (1 g).
The mixture was stirred at room temperature for 6 h. Then,
the mixture was filtered, and the residue was washed with
methylene chloride (DCM). The water was extracted with
DCM (50 mL · 2). The combined organic phase was dried
over anhydrous sodium sulfate, filtered, and the solvent
evaporated to provide a disulfide.
There are several advantages of this reaction over other
methods in the literature. The used monochloro beads
can easily be regenerated by exposure to free chlorine
(bleach).5c The reactions were very clean, gave excellent
reproducible yields, and were facile to apply to various
thiols. Moreover, excellent selectivity was obtained from
these reactions.
In conclusion, the method for oxidizing thiols with
monochloro poly(styrenehydantoin) beads, as reported
in this paper, is a simple, efficient, facile to handle,
very mild procedure for the conversion of thiols to
disulfides.
7. Akdag, A.; Okur, S.; Mckee, M. L.; Worley, S. D. J. Chem.
Theory Comput., in press.
Acknowledgments
8. Arnett, E. M.; Small, L. E. J. Am. Chem. Soc. 1977, 99,
808–816.
9. Freeman, F.; Angeletakis, C. N. J. Org. Chem. 1982, 47,
4194–4200.
This work has been supported by The US Air Force and
the Vanson HaloSource company. The monochloro
beads were kindly supplied by the Vanson HaloSource