JOURNAL OF CHEMICAL RESEARCH 2016 307
Diphenyl sulfide (2e): Colourless oil;17 1H NMR (500 MHz,
DMSO-d6): δ 7.40–7.30 (m, 10H); 13C NMR (125 MHz, DMSO-d6): δ
135.3, 131.2, 130.0, 127.9; MS (EI) m/z: 186 M+.
at the present stage whether intermediate B can release another
reactive sulfur moiety in the acidic ionic liquid to form more
C, the result shows that 1 equiv. of CS2 is enough to convert 2
equiv. of the aryl halide.
Di-p-tolyl sulfide (2f): Colourless oil;17 1H NMR (500 MHz, CDCl3):
δ 7.23 (d, J = 8.1 Hz, 1H), 7.09 (d, J = 7.9 Hz, 1H), 2.32 (s, 6H);
13C NMR (125 MHz, CDCl3): δ 136.9, 132.7, 131.1, 129.9, 21.1; MS (EI)
m/z: 214 [M+].
Conclusion
In summary, a microwave-assisted direct coupling between
aryl halides and carbon disulfide catalysed by the ionic liquid
[DBUH]+[OAc]– has been developed. This protocol utilises
carbon disulfide as a cheap and odourless aryl thiol surrogate.
Good to excellent yields are obtained with aryl iodides although
some aryl chlorides possessing electron-withdrawing groups
also reacted. The ionic liquid [DBUH]+[OAc]– can be easily
recovered and reused for five successive runs with only a slight
decrease in its activity.
Di(2-nitrophenyl) sulfide (2h): Yellow solid; m.p. 118–120 °C (lit.24
1
114–116 °C); H NMR (500 MHz, DMSO-d6): δ 8.21 (d, J = 8.1 Hz,
2H), 7.74–7.63 (m, 4H), 7.40 (d, J = 7.9 Hz, 2H); 13C NMR (125 MHz,
DMSO-d6): δ 154.3, 139.6, 138.9, 135.1, 134.7, 130.7; MS (EI) m/z: 276 M+.
Bis(2-methyl-4-nitrophenyl) sulfide (2i): Yellow solid; m.p.
1
81–83 °C (lit.25 82 °C); H NMR (500 MHz, DMSO-d6): δ 8.27 (s,
2H), 8.04 (d, J = 8.6 Hz, 2H), 7.30 (d, J = 8.6 Hz, 2H), 2.46 (s, 6H);
13C NMR (126 MHz, DMSO-d6) δ 147.2, 141.5, 140.7, 132.0, 125.6,
122.5, 20.3; MS (EI) m/z: 304 M+.
Bis(2-pyridyl) sulfide (2j): Red solid; m.p. 214–216 °C (lit.17
218–220 °C); 1H NMR (500 MHz, DMSO-d6): δ 8.52–8.51 (m,
2H), 7.80–7.76 (m, 2H), 7.47 (d, J = 8.0 Hz, 2H), 7.32–7.30 (m, 2H);
13C NMR (125 MHz, DMSO-d6): δ 156.4, 150.6, 138.1, 126.1, 122.7;
MS (EI) m/z: 187 M+.
Bis(3-pyridyl) sulfide (2k): Colourless oil;13 1H NMR (500 MHz,
CDCl3): δ 8.61 (s, 2H), 8.53–8.52 (m, 2H), 7.66–7.64 (m, 2H),
7.27–7.25 (m, 2H); 13C NMR (125 MHz, CDCl3): δ 151.7, 148.7, 138.8,
131.9, 124.2; MS (EI) m/z: 188 M+.
Experimental
All reagents were obtained from local commercial suppliers and used
without further purification. [DBUH]+[OAc]– was prepared by mixing
DBU with HOAc (1:1 molar ratio) under simple heating. 1H NMR and
13C NMR spectra were recorded on a Bruker AV400 spectrometer in
chloroform-d (CDCl3) or DMSO-d6 using TMS as an internal standard.
GC-MS was recorded on an Agilent Technologies 7890A instrument
with an Agilent 5975C mass detector (EI). All the reactions were
performed in a commercial microwave reactor (XH-200A, Beijing
Xianghu Science and Technology Development Co. Ltd., Beijing,
China).
Dipyrimidin-5-ylsulfane (2l): Yellow oil;23 1H NMR (500 MHz,
CDCl3): δ 9.16 (s, 2H), 8.75 (s, 4H); 13C NMR (125 MHz, DMSO-d6): δ
159.5, 157.8, 130.4; MS (EI) m/z: 190 M+.
CAUTION: Acetic acid, DBU and CS2 can severely affect the skin,
eyes and respiratory system and are also harmful by ingestion. They
should be used in a fume cupboard with all appropriate precautions
taken.
Received 29 January 2016; accepted 4 April 2016
Published online: 29 April 2016
References
Synthesis of aryl thioethers; general procedure
1
D.H.R. Barton and D.W. Ollis, Comprehensive organic chemistry, ed. D.N.
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A sealed 10 mL glass tube containing aryl halide (1 mmol), CS2
(0.5 mmol) and [DBUH]+[OAc]– (1 mL) was placed in the cavity
of a microwave reactor and irradiated for 5–60 min at 100–120 °C
and power 150 W. After cooling to room temperature, the reaction
mixture was extracted with Et2O (3 × 5 mL) and the [DBUH]+[OAc]–
was separated from the product. The organic layers were combined
and the solvent removed under reduced pressure to provide the crude
product, which was further purified by column chromatography on
silica gel using petroleum ether/EtOAc as the eluent. The recovered
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the next reaction. All of the products are known compounds and their
characterisation data were compared and are consistent with literature
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Bis(4-nitrophenyl) sulfide (2a): Yellow solid; m.p. 159–161 °C (lit.21
157–158 °C); 1H NMR (500 MHz, CDCl3): δ 8.21 (d, J = 8.8 Hz, 4H),
7.49 (d, J = 8.8 Hz, 4H); 13C NMR (125 MHz, DMSO-d6): δ 147.2,
142.6, 131.8, 125.2; MS (EI) m/z: 276 M+.
Bis(4-cyanophenyl)sulfide (2b): Orange solid; m.p. 132–134 °C
(lit.22 135–136 °C); 1H NMR (500 MHz, DMSO-d6): δ 7.87 (d, J = 8.5
Hz, 4H), 7.54 (d, J = 8.5 Hz, 4H); 13C NMR (125 MHz, DMSO-d6): δ
140.5, 133.9, 131.6, 118.8, 110.8. MS (EI) m/z: 236 M+.
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Bis[4-(trifluoromethyl)phenyl] sulfide (2c): Colourless oil;23
1H NMR (500 MHz, DMSO-d6): δ 7.76 (d, J = 8.3 Hz, 4H), 7.58 (d,
J = 8.2 Hz, 4H); 13C NMR (125 MHz, DMSO-d6): δ 139.7, 131.7, 128.6
(q, J = 32.3 Hz), 127.0 (q, J = 3.7 Hz), 123.9 (q, J = 272.0 Hz); 19F NMR
(376 MHz, DMSO-d6): δ –62.7; MS (EI) m/z: 322 M+.
Di(4-acetylphenyl) sulfide (2d): Yellow oil;13 1H NMR (500 MHz,
DMSO-d6): δ 7.97 (d, J = 8.5 Hz, 4H), 7.49 (d, J = 8.5 Hz, 4H), 2.58
(s, 6H). 13C NMR (125 MHz, DMSO-d6): δ 197.6, 140.4, 136.2, 130.9,
129.9, 27.2; MS (EI) m/z: 270 M+.