Selective oxidation reactions of diaryl- and dialkyldisulfides to sulfonic acids by CH3ReO3/hydrogen peroxide

Article abstract of DOI:10.1016/j.tetlet.2009.09.011

Diaryl- and dialkyl disulfides were oxidized in acetonitrile at 20 °C by CH₃ReO₃/H₂O₂ oxidant system to yield selectively the corresponding sulfonic acids in short reaction times and in high yields.

Full text of DOI:10.1016/j.tetlet.2009.09.011

Tetrahedron Letters 50 (2009) 6231–6232
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Tetrahedron Letters
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Selective oxidation reactions of diaryl- and dialkyldisulfides to sulfonic acids
by CH3ReO3/hydrogen peroxide
*
Francesco P. Ballistreri, Gaetano A. Tomaselli, Rosa M. Toscano
Dipartimento di Scienze Chimiche, University of Catania, Viale A. Doria 6, I-95125 Catania, Italy
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 1 July 2009
Revised 28 August 2009
Accepted 1 September 2009
Available online 6 September 2009
Diaryl- and dialkyl disulfides were oxidized in acetonitrile at 20 °C by CH3ReO3/H2O2 oxidant system to
yield selectively the corresponding sulfonic acids in short reaction times and in high yields.
Ó 2009 Elsevier Ltd. All rights reserved.
Keywords:
Disulfides
Sulfonic acids
Hydrogen peroxide
Oxidation
Methyltrioxorhenium
Sulfonic acids and their derivatives are very useful chemicals
which industrially find many applications. For instance, free acids
are widely used as catalysts in organic synthesis1 while their salts
and other derivatives form the basis for the manufacture of deter-
gents, water-soluble dyes, and catalysts, sulfonamide pharmaceu-
ticals and ion-exchange resins.2
Several methods are available for the synthesis of sulfonic acids.
Aromatic sulfonic acids are obtained generally by direct sulfonation
of aromatic compounds,3,4 whereas oxidation of sulfur-containing
functional group compounds and reactions of organometallic com-
pounds with amine complexes of sulfur trioxide4 represent some
protocols used to prepare aliphatic sulfonic acids.
Sulfonic acids have classically been prepared by the oxidation of
thiols by several oxidizing agents.5,6 Some of these procedures
suffer from a variety of disadvantages as long reaction times and
indirect and multi-step routes. However, the oxidation routes of
organic sulfur compounds involving peroxides and particularly
hydrogen peroxide are preferred because they are often more con-
venient, very selective, and environmentally friendly.7
Recently, we have reported a mild and convenient one-pot pro-
cedure to oxidize various aromatic and aliphatic thiols, under
homogeneous conditions, to the corresponding sulfonic acids in
high yields employing as a catalyst CH3ReO3 (MTO) in association
with H2O2.8,9
and a diperoxo complex [(CH3)ReO(O2)2], requires a work-up pro-
tocol that is quite simple and produces water as the only
byproduct.10,11
For the formation of sulfonic acids by thiol oxidation a reaction
pathway5,7 has been suggested starting from a proton-coupled
electron transfer step leading to disulfides (a) or from an S-oxygen
transfer step (b) (Scheme 1).
The possibility that disulfides might be intermediates in the
oxidation reactions of thiols (route a) by MTO/H2O2 is of interest
both from a mechanistic and a synthetic point of view, since the
larger availability of disulfides than thiols.
Therefore we deemed worthwhile to start a study on the oxida-
tion reactions of aromatic and aliphatic disulfides by the MTO/
H2O2 system in CH3CN at 20 °C, under homogeneous conditions12
(Scheme 2).
(a)
(b)
RSSR
RSH
RSH
RSO3H
RSO3H
(RSOH)
RSO2H
Scheme 1. Suggested reaction pathways for the formation of sulfonic acids by thiol
oxidation.
The MTO/H2O2 system, which generates in situ two electro-
philic oxidant species, a monoperoxo complex [(CH3)Re(O)2(O2)]
MTO
R-SS-R 5 H2O2
2 RSO3H
4 H2O
CH3CN, 20°C
* Corresponding author. Tel.: +39 095 7385006; fax: +39 095 580138.
E-mail address: rmtoscano@dipchi.unict.it (R.M. Toscano).
Scheme 2. Oxidation of aromatic and aliphatic disulfides to sulfonic acids.
0040-4039/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tetlet.2009.09.011

6232
F. P. Ballistreri et al. / Tetrahedron Letters 50 (2009) 6231–6232
Table 1
Oxidation reactions of disulfides to sulfonic acids with CH3ReO3/H2O2 in CH3CN at 20°Ca
Entry
1
Substrateb
Time (min)
Product
Isolated yields (%)
98
25
SO3H
S
S
2
3
4
20
81
H2C
S
S
S
CH2
CH2 SO3H
10
98
H3CO
O2N
S
OCH3
NO2
H3CO
SO3H
>60
96c
S
S
O2N
SO3H
5
6
7
8
CH3CH2S–SCH2CH3
CH3CH2CH2S–SCH2CH2CH3
(CH3)2CHS–SCH(CH3)2
<1
<1
<1
<1
CH3CH2SO3H
CH3CH2CH2SO3H
(CH3)2CHSO3H
80
90
85
87
CH3(CH2)2CH2S–SCH2(CH2)2CH3
CH3(CH2)2CH2SO3H
a
b
c
Reaction conditions: disulfide (0.6 mmol), 35% H2O2 (6.0 mmol), MTO (0.006 mmol) in CH3CN (5 mL). Excess of H2O2 is removed by catalytic amounts of MnO2.
Conversion 100%.
In CH2Cl2/CH3CN (80/20; 9 mL).
References and notes
R
S
O
1. Tian, S. H.; Shu, D.; Wang, S. J.; Xiao, M.; Meng, Y. Z. Fuel Cells 2007, 7,
Re
+
RSO3H
RSSR
RS(O)SR
S
232–237.
R
O
O
O
Re
2. Boesten, W. H. J.; Quaedflieg, P. J. L. M. PCT Int. Appl. WO 9849133,
1998.
3. Hajipour, A. R.; Mirjalili, Bi Bi F.; Zarei, A.; Khazdooz, L.; Ruoho, A. E. Tetrahedron
Lett. 2004, 45, 6607–6609.
Scheme 3. Nucleophilic attack of disulfide onto a peroxide oxygen of the rhenium
4. (a) Smith, K.; Hou, D. J. Org. Chem. 1996, 61, 1530–1532; (b) El-Hiti, G. A. Sulfur
Reports 2001, 22, 217–250.
peroxo complex generated in situ.
5. Capozzi, G.; Modena, G. In The Chemistry of the Thiol Group; Patai, S., Ed.; 1974;
pp 785–839.
6. Shefer, N.; Carmeli, M.; Rozen, S. Tetrahedron Lett. 2007, 48, 8178–8181.
7. Jones, C. W. In Applications of Hydrogen Proxide and Derivatives; Clark, J. H., Ed.;
Royal Society of Chemistry-Clean Technology Monographs, 1999. Chapter 3, pp
146–155.
8. Catalytic oxidation of sulfenothioic acids with other transition metal peroxo
complexes (e.g., molybdenum) usually stops at the formation of disulfides,
whereas oxidants like MCPBA yield sulfinic acids.
9. Ballistreri, F. P.; Tomaselli, G. A.; Toscano, R. M. Tetrahedron Lett. 2008, 3291–
3293; Ballistreri, F. P.; Tomaselli, G. A.; Toscano, R. M. Synfacts 2008, 7,
0753.
10. Rudolph, J.; Reddy, K. L.; Chiang, J. P.; Sharpless, K. B. J. Am. Chem. Soc. 1997,
119, 6189–6190.
11. Adam, W.; Saha-Moller, C. R.; Weichold, O. J. Org. Chem. 2000, 65, 5001–5004.
and references therein.
12. General procedure for oxidation of disulfides: To a solution of 35% hydrogen
peroxide (6 mmol) in CH3CN (1.5 mL) in a glass reactor, maintained at 20 °C
Pertinent results, reported in Table 1, reveal that disulfides are
oxidized selectively to the corresponding sulfonic acids by the
MTO/H2O2 system in high yields. It is interesting to observe that
the reaction works well employing 1% of catalyst. Dialkyl disulfides
react much faster than diaryl disulfides completing the reaction in
less than 1 min. Electron-donating substituents (entry 3) in the aro-
matic nucleus reduce reaction time whereas electron-withdrawing
groups (entry 4) slow down the reaction rate, but the reaction is still
efficient. Note that to the best of our knowledge, direct oxidation of
organic disulfides containing nitro groups to the corresponding sul-
fonic acids is unprecedented. These findings seem in accord with an
electrophilic oxygen transfer13 step which envisages a rate-deter-
mining nucleophilic attack of disulfide onto a peroxide oxygen of
the rhenium peroxo complex generated in situ (Scheme 3).
The results displayed in Table 1 compared with those reported
previously9 for the oxidation reactions of thiols by the MTO/H2O2
oxidant system seem consistent with the intermediacy of disul-
fides in the oxidation of thiols to sulfonic acids. In fact, under the
same experimental conditions adopted for the oxidation reactions
of thiols by MTO/H2O2, disulfides structurally correlated to thiols
yield the same sulfonic acids with reaction times shorter than thi-
ols themselves.
by
a thermostatic bath, was added a solution of methyltrioxorhenium
(Aldrich) (0.006 mmol) in CH3CN (1 mL). This yellow mixture was stirred for
1 min. Then a solution of disulfide (0.6 mmol) in CH3CN (2.5 mL) was added
and the stirring was continued for
a suitable reaction time. After the
disappearance of disulfide (monitored by TLC), a catalytic amount of MnO2
was added.14 The organic phase was concentrated under reduced pressure.
The crude product obtained was purified by column chromatography
(chloroform and acetonitrile as eluents) over silicic acid (100 mesh,
Aldrich). The 1H NMR spectra were recorded at 500 MHz and 13C NMR at
125 MHz. All the products are known compounds and were easily identified
by comparison of their spectroscopic data with those reported in the
literature.4a,15
In conclusion this one-pot procedure to obtain aromatic and
aliphatic sulfonic acids from disulfides is very simple and very
selective, requires short reaction times, and affords high yields.
The use of hydrogen peroxide as the oxygen donor and the larger
availability of disulfides than thiols make very appealing this envi-
ronmentally friendly method.
13. (a) Herrmann, W. A.; Fischer, R. W.; Scherer, W.; Rauch, M. U. Angew. Chem., Int.
Ed. Engl. 1993, 32, 1157–1160; (b) Vassel, K.; Espenson, J. Inorg. Chem. 1994, 33,
5491–5498; (c) Abu-Omar, M. M.; Hansen, P. J.; Espenson, J. H. J. Am. Chem. Soc.
1996, 118, 4966–4974; (d) Gisdakis, P.; Yudanov, I. V.; Rösch, N. Inorg. Chem.
2001, 40, 3755–3765.
14. Coperet, C.; Adolfsson, H.; Sharpless, K. B. J. Chem. Soc., Chem. Commun. 1997,
1565–1566.
15. (a) Freeman, F.; Angeletakis, N. Org. Magn. Reson. 1983, 21, 86–93; (b)
Bassindale, A. R.; Iley, J. H. In The NMR and ESR Spectra of Sulphonic Acid and
their Derivatives; Patai, S., Rappoport, Z., Eds.; 1991; pp 197–247.
Acknowledgments
We thank M.I.U.R. and the University of Catania for financial
support.