Dimercaptoethane oxirane ring opening reaction: β,β′-dihydroxy dithioether synthesis

Article abstract of DOI:10.1016/S0040-4039(01)00268-4

The action of dimercaptoethane on alkyl oxiranes in the presence of benzyltrimethylammonium hydroxide (Triton B) allows, via regiospecific opening reaction, the preparation of the corresponding β,β′-dihydroxy dithioethers in excellent yields.

Full text of DOI:10.1016/S0040-4039(01)00268-4

TETRAHEDRON
LETTERS
Pergamon
Tetrahedron Letters 42 (2001) 3167–3169
Dimercaptoethane oxirane ring opening reaction: b,b%-dihydroxy
dithioether synthesis
Moufida Romdhani Younes,a Mohamed Moncef Chaabounib and Ahmed Bakloutia,*
aLaboratoire de Chimie Structurale Organique, Faculte´ des Sciences de Tunis, 1060 Tunis, Tunisia
bEcole Supe´rieure des Industries Alimentaires, 58 Avenue Alain Savary, 1003 Tunis, Tunisia
Received 24 May 2000; accepted 15 February 2001
Abstract—The action of dimercaptoethane on alkyl oxiranes in the presence of benzyltrimethylammonium hydroxide (Triton B)
allows, via regiospecific opening reaction, the preparation of the corresponding b,b%-dihydroxy dithioethers in excellent yields.
© 2001 Elsevier Science Ltd. All rights reserved.
The ring opening of oxiranes1 with various nucleophiles
is an important synthetic transformation in organic
chemistry. The preparation of b-hydroxy thioethers is
generally realized by the action of thiolates2 or thiols in
the presence of acids or metal salts.3 Ring opening
reaction by thiols was also carried out in the presence of
alumina4 or polyethylene glycol.5 This reaction has been
recently performed in hexafluoroisopropanol without a
catalyst.6 Herein, we report the ring opening reaction of
two mole equivalents of epoxides with dimercaptoethane
using benzyltrimethylammonium hydroxide (Triton B)
as catalyst7 (Scheme 1).
molecule are far from each other so they could not be
discerned by NMR technique. The H NMR spectrum
shows a sharp singlet for the two methylene groups of
the dimercaptoethane moiety.
1
This is not the case for the cyclohexanic compound 2g,
for which two singlets of the same intensity were observed
for these methylene groups. The existence of two
diastereomers for the cyclohexanic compound may be
explained if we assume that the cyclohexene oxide 1g
gave exclusively trans products,9,10 which were formed as
an equimolar mixture of meso and threo11 (Scheme 2).
As shown in Table 1, this reaction allows the preparation
of b,b%-dihydroxy dithioethers in excellent yields. For the
starting oxiranes 1a–e, the epoxide ring was regiospecifi-
cally opened by nucleophilic attack on the terminal
carbon atoms affording a secondary diol. This regiospe-
cificity was not observed in the case of styrene oxide 1f,
which gave a mixture of three isomeric derivatives.8
Compounds 2a–f should be obtained as a mixture of
diastereomers, but the two stereogenic centers within the
By adding D
-camphosulfonic acid,12 splitting of one of
the two singlets was not observed, but the more
deshielded one broadens so it may be attributed to the
threo isomer.
The b,b%-dihydroxy dithioethers obtained were character-
ized by spectroscopic and HRMS methods.13 These new
compounds may be useful intermediates for the synthesis
of lipophilic thiacrown ethers.14
Scheme 1.
Keywords: epoxides; dimercaptoethane; thioethers.
* Corresponding author. Tel.: 216 1 872 600; fax: 216 1 885 008.
0040-4039/01/$ - see front matter © 2001 Elsevier Science Ltd. All rights reserved.
PII: S0040-4039(01)00268-4

3168
M. Romdhani Younes et al. / Tetrahedron Letters 42 (2001) 3167–3169
Table 1. Ring opening of epoxides with dimercaptoethane
aThe ratio of the three isomers was determined by GC and 1H NMR.bThe mixture of isomeric products was purified by column chromatography
(silica gel, hexane–diethyl ether, 1:1).

M. Romdhani Younes et al. / Tetrahedron Letters 42 (2001) 3167–3169
3169
Scheme 2.
Acknowledgements
2g exhibited good integrals but it showed two signals for
OH and CH2S. The isomers ratio is determined from
CH2S signals intensity.
We thank Professor J. Courtieu and F. Perez for
HRMS realization.
12. Russi, M.; Szanto, T.; Vasiolini, V. G.; Balog, A.; Mure-
san, V.; Nicoara, T. N. Chem. Abstr. 1974, 80, 108851u.
13. Spectral data: compound 2a: 1H NMR (300 MHz,
CDCl3): l=1.25 (d, J=6.3 Hz, 6H), 2.51 (m, 2H), 2.73
(m, 2H), 2.78 (s, 4H), 2.95 (br, 2H), 3.87 (m, 2H). 13C
NMR (75 MHz, CDCl3): l=21.98 (2CH3), 32.43
(2CH2S), 41.42 (2CH2), 65.95 (2CH). HRMS: mol. mass
calcd 233.064595 (for C8H18NaO2S2), found 233.064180
References
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(M+Na)+. Compound 2b: H NMR (300 MHz, CDCl3):
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l=0.97 (t, J 7.5 Hz, 6H), 1.54 (m, 4H), 2.52 (m, 2H),
2.75 (m, 2H), 2.78 (s, 4H), 2.95 (br, 2H), 3.61 (m, 2H).
13C NMR (75 MHz, CDCl3): l=9.82 (2CH3), 28.87
(2CH2), 32.24 (2CH2S), 39.46 (2CH2), 71.02 (2CH).
HRMS: mol. mass calcd 239.113950 (for C10H23O2S2),
found 239.113090 (M+H)+. Compound 2c: 1H NMR (300
MHz, CD3COCD3): l=2.78 (m, 4H), 2.84 (S, 4H), 3.69
(m, 4H), 3.98 (br, 2H), 4.48 (m, 2H). 13C NMR (75 MHz,
CD3COCD3): l 33.21 (2CH2S), 36.21 (2CH2), 48.68
(2CH2Cl), 71.56 (2CH). HRMS: mol. mass calcd
300.98665 (for C8H16NaO2S2Cl2), found 300.98704 (M+
1
Na)+. Compound 2d: H NMR (300 MHz, CD3COCD3):
l=2.78 (m, 4H), 2.84 (S, 4H), 4.03 (m, 2H), 4.11 (m,
2H), 4.13 (m, 4H), 6.88–7.27 (m, 10H). 13C NMR (75
MHz, CD3COCD3): l=33.14 (2CH2S), 35.83 (2CH2),
69.95 (2CH2O), 70.95 (2CH), 114.94, 121.13, 120.78,
159.27 (2Ph); mol. mass calcd 417.11702 (for
C20H26NaO4S2), found 417.11728 (M+Na)+. Compound
6. Kesavan, V.; Bennet-delpar, D.; Be´gue´, J. P. Tetrahedron
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1
7. Dimercaptoethane (27 mmol) was added dropwise over
30 minutes to a stirred solution of epoxide 1 (50 mmol)
and Triton B (1.5 mmol) at room temperature. The
consumption of the epoxide was monitored by TLC
(silica gel 60 F254, hexane–diethylether, 1:1). The obtained
mixture was purified by distillation (2a and 2b), column
chromatography (2f, 2c) and by recrystallization from
carbon tetrachloride (2d, 2e and 2g).
2e: H NMR (300 MHz, CD3COCD3): l=2.88–2.99 (m,
8H), 4.40 (m, 2H), 5.67 (br, 2H). 19F NMR (282 MHz,
C6F6): l=85.54 (6F, 2CF3), 47.81 (2F, 2CFAa), 45.36
(4F, 2CF2d), 44.70 (12F, 2CF2d, 2CF2o, CF2z), 43.89 (4F,
2CF2b), 40.43 (4F, 2CF2v), 40.28 (2F, 2CFBa) mol. mass
calcd 1040.96335 (for C24H12NaO2S2), found 1040.96340
1
(M+Na)+. Compound 2g: H NMR (300 MHz, CDCl3):
l=1.26–1.40 (m, 8H), 1.74 (m, 4H), 2.09 (m, 4H), 2.41
(m, 2H), 2.80 and 2.83 (two singlets, 4H), 3.18 and 3.37
(two peaks, 2H), 3.31 (m, 2H). 13C NMR (75 MHz,
CDCl3): l=24.22, 26.08, 30.77 and 31.16 (two peaks),
32.92 and 33.01 (two peaks), 33.87, 53.38 and 53.47 (two
peaks), 72.46 and 72.83 (two peaks). HRMS: mol. mass
calcd 313.127195 (for C14H26NaO2S2), found 313.127210
(M+Na)+.
8. Compound 2f. HRMS: mol. mass calcd 335.113950 (for
C18H23O2S2), found 335.113860 (M+H)+.
9. De Sousa, A. S.; Hancock, R. O. J. Chem. Soc., Chem.
Commun. 1995, 415–416.
10. Epoxides are normally subsect to anti ring opening. Rick-
born, B. In Comprehensive Organic Synthesis; Trost, B.
M., Ed.; Pergamon Press: Oxford, 1991; pp. 733–734.
11. Examination of the 13C NMR spectra of 2g showed
14. Guyon, V.; Guy, A.; Foos, J.; Lemaire, M.; Draye, M.
Tetrahedron 1995, 51, 4065–4074.
1
doubling of a number of the peaks. H NMR spectra of
.
.