DOI: 10.1039/C5RA19112B
Paper
RSC Advances
recorded on a Bruker (Avance) 300 MHz NMR instrument using
TMS as internal standard and CDCl3 as solvent. Standard
Bruker soware was used throughout. Chemical shis are given
in parts per million (d-scale) and the coupling constants are
given in Hertz. Silica gel-G plates (Merck) were used for TLC
analysis with a mixture of petroleum ether (60–80 ꢀC) and ethyl
acetate as eluent. Elemental analyses were performed on a Per-
kin Elmer 2400 Series II Elemental CHN analyzer. Mass spectra
were recorded in LCQ Fleet mass spectrometer, Thermo Fisher
Instruments Limited, US. Electrospray ionisation mass spec-
trometry (ESI-MS) analysis was performed in the positive ion
mode on a liquid chromatography ion trap.
4-Hydroxy-3-(p-tolyl)thiazolidine-2-thione 3e. Isolated as
white solid; yield 94%; mp ¼ 130–131 ꢀC [143–44 ꢀC];20 1H NMR
(300 MHz, CDCl3) dH: 2.39 (s, 3H), 3.29 (dd, J ¼ 12.3, 1.5 Hz, 1H),
3.63 (brs, 1H), 3.86 (dd, J ¼ 12.1, 6.1 Hz, 1H), 5.78 (brs, 1H),
7.41–7.72 (m, 4H); 13C NMR (75 MHz, CDCl3) dC: 20.8, 36.7, 92.4,
127.9, 129.4, 136.7, 137.5, 196.8; anal. calcd for C10H11NOS2: C,
53.31; H, 4.92; N, 6.22%. Found: C, 53.35; H, 4.99; N, 6.17%. ESI-
MS: m/z. Calcd: 225.03; found: 226.03 (M + 1).
3-(4-Ethylphenyl)-4-hydroxythiazolidine-2-thione 3f. Isolated
as white solid; yield: 93%; mp ¼ 148–149 ꢀC; 1H NMR (300 MHz,
CDCl3 + DMSO-d6) dH: 1.25 (t, J ¼ 7.6 Hz, 3H), 2.68 (q, J ¼ 7.5 Hz,
2H), 3.28 (d, J ¼ 12.0 Hz, 1H), 3.81 (dd, J ¼ 6.3, 12.0 Hz, 1H), 5.79
(t, J ¼ 6.6 Hz, 1H), 6.79 (d, J ¼ 8.4 Hz, 1H), 7.28 (d, J ¼ 8.1 Hz,
2H), 7.33 (d, J ¼ 8.4 Hz, 2H); 13C NMR (75 MHz, CDCl3 + DMSO-
d6) dC: 15.5, 27.9, 36.7, 92.4, 127.9, 128.2, 136.9, 143.6, 196.8;
anal. calcd for C11H13NOS2; C, 55.20; H, 5.47; N, 5.85%. Found:
C, 55.14; H, 5.52; N, 5.76%. ESI-MS: m/z. Calcd: 239.04; found:
239.99 (M + 1).
General procedure for the synthesis of 4-hydroxy-3-
arylthiazolidine-2-thiones, 3a–m
A vial containing a mixture of arylisothiocyanate (1 mmol) 1 and
1,4-dithiane-2,5-diol (0.5 mmol) 2 was placed in a microwave
synthesizer. The vial was subjected to microwave irradiation
programmed at 110 ꢀC, 120 W and 1 bar pressure. Aer 3–4 min
of irradiation, the mixture was cooled to room temperature.
Then the crude reaction mixture was triturated with cold
ethanol to give pure products.
3-(4-Fluorophenyl)-4-hydroxythiazolidine-2-thione 3a. Iso-
lated as off white solid. Yield: 88%; mp ¼ 166–167 ꢀC; 1H NMR
(300 MHz, DMSO-d6) dH: 3.20 (d, J ¼ 12.0 Hz, 1H), 3.89 (dd, J ¼
6.3, 12.0 Hz, 1H), 5.87 (t, J ¼ 7.05 Hz, 1H), 7.28–7.35 (m, 2H),
7.38–7.43 (m, 2H); 13C NMR (75 MHz, DMSO-d6) dC: 36.3, 91.9,
115.4 (d, 2JC,F ¼ 22.6 Hz), 130.0 (d, 3JC,F ¼ 8.8 Hz), 135.1, 160.9
(d, 1JC,F ¼ 243.3 Hz), 196.9; anal. calcd for C9H8FNOS2; C, 47.15;
H, 3.52; N, 6.11%. Found: C, 47.10; H, 3.56; N, 6.19%. ESI-MS:
m/z. Calcd: 229.00; found: 230.00 (M + 1).
3-(4-Chlorophenyl)-4-hydroxythiazolidine-2-thione 3b. Iso-
lated as off white solid. Yield: 90%; mp ¼ 153–154 ꢀC; 1H NMR
(300 MHz, DMSO-d6) dH: 3.20 (d, J ¼ 11.7 Hz, 1H), 3.90 (dd, J ¼
6.6, 11.8 Hz, 1H), 5.90 (t, J ¼ 6.0 Hz, 1H), 7.35–7.47 (m, 2H), 7.55
(d, J ¼ 8.7 Hz, 2H); 13C NMR (75 MHz, DMSO-d6) dC: 36.8, 92.2,
128.9, 130.0, 132.5, 138.1, 197.3; anal. calcd for C9H8ClNOS2: C,
43.99; H, 3.28; N, 5.70%. Found: C, 44.08; H, 3.23; N, 5.73%. ESI-
MS: m/z. Calcd: 244.97; found: 246.05 (M + 1).
4-Hydroxy-3-(4-isopropylphenyl)thiazolidine-2-thione
3g.
1
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Isolated as white solid; yield: 95%; mp ¼ 186–187 C; H NMR
(300 MHz, DMSO-d6) dH: 1.21 (d, J ¼ 7.2 Hz, 3H), 1.23 (d, J ¼ 3.3
Hz, 3H), 2.88–2.95 (m, 1H), 3.17 (d, J ¼ 12.0 Hz, 1H), 3.88 (ddd, J
¼ 3.2, 6.5, 11.9 Hz, 1H), 5.83 (m, 1H), 7.27–7.34 (m, 4H); 13C
NMR (75 MHz, DMSO-d6) dC: 23.8, 33.2, 36.7, 92.4, 126.8, 127.9,
136.9, 148.1, 196.8; anal. calcd for C12H15NOS2; C, 56.88; H,
5.97; N, 5.53%. Found: C, 56.98; H, 6.02; N, 5.60%. ESI-MS: m/z.
Calcd: 253.06; found: 254.04 (M + 1).
4-Hydroxy-3-(4-methoxyphenyl)thiazolidine-2-thione
3h.
ꢀ
Isolated as white solid; yield: 92%; mp ¼ 176–177 C [162–63
ꢀC];20 1H NMR (300 MHz, CDCl3 + DMSO-d6) dH: 3.02 (m, 1H),
3.54–3.59 (m, 4H), 4.45 (brs, 1H), 5.53 (brs, 1H), 6.71–6.79 (m,
2H), 7.07–7.17 (m, 2H); 13C NMR (75 MHz, DMSO-d6) dC: 36.5,
55.4, 92.3, 114.1, 129.3, 131.9, 158.7, 196.9; anal. calcd for
C
10H11NO2S2; C, 49.77; H, 4.59; N, 5.80%. Found: C, 49.69; H,
4.64; N, 5.89%. ESI-MS: m/z. Calcd: 241.02; found: 241.98 (M +
1).
3-(3-Fluorophenyl)-4-hydroxythiazolidine-2-thione 3i. Iso-
lated as white solid; yield: 93%; mp ¼ 175–176 ꢀC; 1H NMR (300
MHz, DMSO-d6) dH: 3.21 (dd, J ¼ 7.2, 12.1 Hz, 1H), 3.89 (dd, J ¼
6.6, 12.0 Hz, 1H), 5.93–5.95 (m, 1H), 7.24–7.29 (m, 2H), 7.39 (d, J
¼ 7.5 Hz, 1H), 7.48–7.55 (m, 1H); 13C NMR (75 MHz, DMSO-d6)
dC: 36.9, 92.3, 114.9 (d, 2JC,F ¼ 20.0 Hz), 115.3 (d, 2JC,F ¼ 23.3 Hz),
3-(4-Bromophenyl)-4-hydroxythiazolidine-2-thione 3c. Iso-
lated as off white solid. Yield: 92%; mp ¼ 148–149 ꢀC; 1H NMR
(300 MHz, CDCl3) dH: 3.31 (dd, J ¼ 1.5, 12.3 Hz, 1H), 3.63 (d, J ¼
9.3 Hz, 1H), 3.89 (dd, J ¼ 6.0, 12.3 Hz, 1H), 5.79 (t, J ¼ 5.7 Hz,
1H), 7.31–7.36 (m, 2H), 7.57–7.62 (m, 2H); 13C NMR (75 MHz,
CDCl3 + DMSO-d6) dC: 36.5, 91.6, 121.1, 129.1, 131.4, 137.7,
197.4; anal. calcd for C9H8BrNOS2; C, 37.25; H, 2.78; N, 4.83%.
Found: C, 37.32; H, 2.89; N, 4.88%. ESI-MS: m/z. Calcd: 288.92;
found: 287.94 (M ꢁ 1), 289.91 (M + 1).
124.4 (d, 4JC,F ¼ 2.8 Hz), 130.5 (d, 3JC,F ¼ 8.9 Hz), 140.7 (d, 3JC,F
¼
1
10.2 Hz), 161.8 (d, JC,F ¼ 242.8 Hz), 197.3; anal. calcd for
C9H8FNOS2: C, 47.15; H, 3.52; N, 6.11%. Found: C, 47.18; H,
3.48; N, 6.17%. ESI-MS: m/z. Calcd: 229.00; found: 230.00 (M +
1).
3-(3-Bromophenyl)-4-hydroxythiazolidine-2-thione 3j. Iso-
lated as white solid; yield: 91%; mp ¼ 124–125 ꢀC; 1H NMR (300
MHz, CDCl3 + DMSO-d6) dH: 3.29–3.33 (m, 1H), 3.82 (d, J ¼ 6.3,
12.0 Hz, 1H), 5.81 (t, J ¼ 6.0 Hz, 1H), 7.22 (d, J ¼ 8.1 Hz, 1H),
7.35–7.40 (m, 1H), 7.50–7.53 (m, 1H), 7.63 (m, 1H); 13C NMR (75
MHz, DMSO-d6) dC: 36.9, 92.3, 121.2, 127.5, 130.8, 130.9, 140.7,
197.4; anal. calcd for C9H8BrNOS2; C, 37.25; H, 2.78; N, 4.83%.
Found: C, 37.18; H, 2.89; N, 4.87%. ESI-MS: m/z. Calcd: 288.92;
found: 289.92 (M + 1), 291.88 (M + 2).
4-Hydroxy-3-phenylthiazolidine-2-thione 3d. Isolated as off
white solid. Yield: 96%; mp ¼ 157–158 C [168 C];20 1H NMR
(300 MHz, DMSO-d6) dH: 3.20 (dd, J ¼ 2.1, 12.0 Hz, 1H), 3.91 (dd,
J ¼ 6.3, 12.0 Hz, 1H), 5.88–5.93 (m, 1H) 7.32–7.41 (m, 3H), 7.45–
7.56 (m, 2H); 13C NMR (75 MHz, DMSO-d6) dC: 36.8, 92.4, 128.0,
128.1, 128.9, 139.3, 196.9; anal. calcd for C9H9NOS2: C, 51.16; H,
4.29; N, 6.63%. Found: C, 51.24; H, 4.33; N, 6.68%. ESI-MS: m/z.
Calcd: 211.01; found: 212.08 (M + 1).
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90454 | RSC Adv., 2015, 5, 90451–90456
This journal is © The Royal Society of Chemistry 2015