PAPER
Reaction between Epoxides and Carbon Disulfide under Hydrotalcite Catalysis
55
3J = 10.8, 4.5 Hz, 1 H, OCH2CH), 3.84 (dd, 3J = 10.8, 4.9 Hz, 1 H,
OCH2CH), 4.58 (d, J = 11.9 Hz, 1 H, CH2Ph), 4.63 (d, J = 11.9
Hz, 1 H, CH2Ph), 5.2–5.3 (m, 1 H, CH), 7.2–7.4 (m, 5 H, Harom).
13C NMR (75 MHz; CDCl3/TMS): d = 36.1, 68.5, 73.7, 89.2, 127.8,
128.1, 128.5, 137.1, 211.9.
S
S
3
3
S
S
O
S
S
O
S
+
+
O
S
S
O
+
3e
4e
Ph
Ph
S
Ph
Ph
3e
4e
MS (EI, 70 eV): m/z (%) = 91 (100), 107 (40), 147 (10), 240 (3)
S
S
[M+].
50 °C
75 °C
Ph
Anal. Calcd for C11H12O2S2: C, 43.60; H, 5.04; S, 26.72. Found: C,
43.42; H, 4.98; S, 26.56.
Ph
O
6e
7e
+ CS2
100 °C
S
Ph
25 °C
5-(Isopropoxymethyl)-1,3-oxathiolane-2-thione (3c)
Bp 135–137 °C.
1H NMR (300 MHz, CDCl3/TMS): d = 1.12 (dd, 3J = 6.1, 1.2 Hz, 6
H, 2 CH3), 3.5–3.8 (m, 5 H, OCH2CHCH2S), 5.1–5.3 [m, 1 H,
CH(CH3)2].
13C NMR (75 MHz, CDCl3/TMS): d = 21.9, 36.1, 66.7, 72.7, 89.9,
212.4.
S
S
NO REACTION
6e
Ph
Scheme 2 Product distribution as a function of temperature in the
reaction between styrene oxide and carbon disulfide
MS (EI, 70 eV): m/z (%) = 57 (100), 74 (91), 131 (51), 192 (79)
At 50 °C 3e and 4e are obtained in 83% total yield (3e/
4e = 62:38), by carrying out the reaction at 75 °C, byprod-
ucts 6e and 7e were also produced (91% total yield, 3e/4e/
6e/7e = 43:13:22:22) and by increasing the temperature
up to 100 °C, the trithiocarbonate 6e was isolated as the
sole reaction product (98% yield).
[M+].
Anal. Calcd for C7H12O2S2: C, 43.79; H, 6.30; S, 33.40. Found: C,
43.60; H, 6.38; S, 33.45.
5-Oxiran-2-yl-1,3-oxathiolane-2-thione (3g)
Bp 118–119.5 °C.
Finally, we faced the problem of catalyst recycling; at the
end of the model reaction the crude was filtered and the
catalyst, after washing with carbon disulfide, was reused
for at least four times affording product 3a with the same
high yield (reaction: 99%; 1st recycle: 98%; 2nd recycle:
97%; 3rd recycle: 99%; 4th recycle: 98%).
1H NMR (300 MHz, CDCl3/TMS): d = 2.9–3.0 (m, 2 H, OCH2),
3.3–3.4 (m, 1 H, OCH2CH), 3.6–3.7 (m, 2 H, SCH2), 5.0–5.2 (m, 1
H, SCH2CH).
13C NMR (75 MHz, CDCl3/TMS): d = 35.9, 44.2, 51.0, 89.1, 210.9.
MS (EI, 70 eV): m/z (%) = 57 (35), 71 (39), 162 (100) [M+].
Anal. Calcd for C5H6O2S2: C, 37.03; H, 3.73; S, 39.59. Found: C,
36.96; H, 3.65; S, 39.68.
In conclusion we have shown for the first time that a het-
erogeneous catalyst, namely commercially available hy-
drotalcite MG30, can be successfully and efficiently
utilized for the highly selective synthesis of cyclic dithio-
carbonates. Moreover, the use of carbon disulfide as sol-
vent–reagent, the high atom economy, and the possibility
of recycling the catalyst for several runs, make this ap-
proach practical and environmentally acceptable.
Acknowledgment
The authors thank the support of the Ministero dell’Istruzione,
dell’Università e della Ricerca (MIUR), Italy. The authors are also
grateful to the Centro Interdipartimentale Misure (CIM) for the use
of NMR instruments. The authors are indebted with Dr. Alexander
Malyschew (SASOL-Germany) for donation of the hydrotalcite
samples.
All compounds were purchased from Aldrich and used without fur-
1
ther purification. H (300 MHz) and 13C (75 MHz) NMR spectra
References
were recorded on a Bruker Avance 300 spectrometer. MS spectra
were obtained with a HP 5971 A Mass Selective Detector.
(1) (a) Corma, A. Chem. Rev. 1995, 95, 559. (b) Sheldon, R. A.
CHEMTECH 1991, 566. (c) Arends, I. W. C. E.; Sheldon,
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Chapman and Hall: London, 1995.
1,3-Oxathiolane-2-thiones 3; General Procedure
Epoxide 1 (10 mmol), CS2 (3 mL), and hydrotalcite MG 30 (0.75 g)
were successively added to a test tube, which was stopped and the
mixture was magnetically stirred (800 rpm) at 50 °C for 5 h. After
cooling to r.t. the catalyst was separated by Büchner filtration,
washed with CS2 (10 mL), and the solvent removed under reduced
pressure. The crude residue was column chromatographed (silica
gel, hexane–EtOAc, 70:30) to afford the products. Spectral data of
known dithiocarbonates 3a and 3d–f are in accordance with litera-
ture data.5c,10
(3) Sheldon, R. A. CHEMTECH 1994, 38.
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Itagaki, Y.; Sudo, A.; Endo, T. J. Polym. Sci., Part A: Polym.
Chem. 2005, 43, 3711.
5-(Benzyloxymethyl)-1,3-oxathiolane-2-thione (3b)
Bp 55–56 °C/0.026 mbar.
1H NMR (300 MHz, CDCl3/TMS): d = 3.58 (dd, 3J = 11.1, 7.2 Hz,
3
1 H, CH2S), 3.67 (dd, J = 11.1, 8.1 Hz, 1 H, CH2S), 3.76 (dd,
Synthesis 2008, No. 1, 53–56 © Thieme Stuttgart · New York