ꢁꢁꢁꢂ
4ꢀ ꢀD. Gautam etꢃal.: Thiazolidin-4-ones and perhydro-1,3-thiazin-4-ones
Synthesis of N-methylpyridinium p-toluene- Solvent-free procedure for synthesis of 3
sulfonate (ionic liquid)
An equimolar mixture of 1 (0.025 mol) and 3-chloropropionic acid
(2.71 g, 0.025 mol) and the ionic liquid (2.0 g) was stirred at 100°C
Pyridine (0.55 mol) was added to methyl p-toluenesulfonate (0.5 mol)
for 6 h. After the reaction was completed, as monitored by TLC, the
at 0–10°C and the mixture was stirred at room temperature for 1 h.
mixture was poured into ice-cold water. The resultant precipitate of 3
The resultant solid of N-methylpyridinium p-toluenesulfonate was
was filtered, dried and crystallized from ethanol (Table 3).
filtered, washed with ethyl acetate to remove unreacted substrates
and dried. The physical parameters of the ionic liquid were in good
agreement with those reported in the literature [21].
Conventional procedure for synthesis of 3
A mixture of 1 (0.005 mol), 3-chloropropionic acid (0.54 g, 0.005 mol),
Solvent-free procedure for synthesis of 2
anhydrous sodium acetate (0.8 g, 0.010 mol), glacial acetic acid (3.0
mL) and acetic anhydride (1.0 mL) was heated under reflux for 10–14
A mixture of 1 (0.025 mol), 2-bromopropionic acid (3.8 g, 0.025 mol)
h. The mixture was cooled to room temperature and poured into ice-
and the ionic liquid (2.0 g) was stirred at 100°C for 4 h. Afer the reac-
cold water. The gummy product obtained was extracted with ethyl
tion was completed, as monitored by TLC, the mixture was poured
acetate (2 × 25 mL). The extract was washed with water, dried over
into ice-cold water. The resultant precipitate of 2 was filtered, dried
anhydrous Na2SO4 and concentrated under reduced pressure. The
and crystallized from ethanol (Table 3).
solid residue of 3 was crystallized from ethyl acetate.
2-{(E)-[3,4-Dihydronaphthalene-1(2H)-ylidene]hydrazono}-perhy-
Conventional procedure for synthesis of 2
dro-1,3-thiazin-4-one (3a)ꢁMp 154–156°C; IR: ν 1697 (N-CO) 1589
(CN), 1543ꢀcm-1 (CC); 1H NMR (CDCl3): δ 1.89 (m, 2H, CH2), 2.79–3.07
A mixture of 1 (0.015 mol), 2-bromopropionic acid (2.3 g, 0.015 mol),
anhydrous sodium acetate (2.46 g, 0.03 mol) and absolute ethanol
(5 mL) was heated under reflux for 10 h. The mixture was cooled to
room temperature and then poured into ice-cold water. The sepa-
rated solid was filtered, washed with water and crystallized from
ethanol (Table 3).
(m, 8H, 4CH2), 7.15 (t, 1H, ArH, J = 7 Hz), 7.21–7.34 (m, 2H, ArH), 8.24
(dd, 1H, ArH, J = 7 Hz, J = 2 Hz), 9.72 (br, 1H, NH exchangeable with
D2O); 13C NMR (CDCl3): δ 169.4 (CO), 162.4 (CN), 140.9, 132.5, 130.3,
128.8, 126.3, 125.4 (ArC), 34.3 (SCH2), 29.9, 27.4, 23.2, 22.7, 22.1 (CH2); MS:
m/z 274 (M+H)+ (20), 233 (34), 231 (100%). Anal. Calcd for C14H15N3SO:
C, 61.53; H, 5.49; N, 15.38; S, 11.72. Found: C, 61.45; H, 5.44; N, 15.32; S,
11.80.
2-{(E)-[3,4-Dihydro-2H-naphthalen-(1E)-ylidene]-hydrazono}-
5-methylthiazolidin-4-one (2c) Mp 158–160°C; IR: ν 3132 (NH), 1713
(N-CO), 1612ꢀcm-1 (CN); 1H NMR (CDCl3): δ 1.68 (d, 3H, CH3, J = 7 Hz),
1.90 (m, 2H, CH2), 2.81 (t, 2H, CH2, J = 6 Hz), 2.89 (t, 2H, CH2, J = 7 Hz),
4.06 (q, 1H, SCH, J = 7 Hz), 7.15 (d, 1H, ArH, J = 7 Hz), 7.23 (d, 1H, ArH,
J = 7 Hz), 7.30 (t, 1H, ArH, J = 7 Hz), 8.21 (dd, 1H, ArH, J = 7 Hz, J = 1
Hz); 13C NMR (CDCl3): δ 175.9 (CO), 162.2 (CN), 140.9, 132.12, 130.25,
128.7, 126.4, 125.5 (ArC), 42.5 (SCH), 29.8 (CH2), 27.5 (CH2), 22.1 (CH2), 19.1
(CH3); MS: m/z 274 (M+H+, 100%). Anal. Calcd for C14H15N3SO: C, 61.53;
H, 5.49; N, 15.38; S, 11.72. Found: C, 61.58; H, 5.60; N, 15.49; S, 11.83.
2-{(E)-[6-Methoxy-3,4-dihydronaphthalen-1(2H)-ylidene]
hydrazono}-perhydro-1,3-thiazin-4-one (3b)ꢁMp 139–140°C; IR:
1
ν 1697 (N-CO), 1589 (CN), 1551ꢀcm-1 (CC); H NMR (CDCl3): δ
1.85–2.17 (m, 2H, CH2), 2.76–3.16 (m, 6H, 3CH2), 3.83 (s, 3H, OCH3), 6.65
(m, 1H, ArH), 6.78–6.81 (dd, 1H, ArH, J = 6 Hz, J = 3 Hz), 8.17 (m, 1H,
ArH), 9.74 (br, 1H, NH exchangeable with D2O); 13C NMR (CDCl3): δ
169.5 (CO), 162.6 (CN), 140.8, 132.1, 130.1, 127.2, 125.1, 123.4 (ArC),
58.9 (OCH3), 33.4 (SCH2), 28.9, 27.2, 23.1, 22.4, 22.6 (CH2); MS: m/z 304
(M+H)+ (20%). Anal. Calcd for C15H17N3O2S: C, 59.40; H, 5.61; N, 13.86;
S, 10.56. Found: C, 59.33; H, 5.56; N, 13.78; S, 10.45.
2-{(E)-[6-Methoxy-3,4-dihydronaphthalen-1(2H)-ylidene]-hy-
drazono}-5-methyl-thiazolidin-4-one (2d) Mp 172–174°C; IR: ν
3070 (NH), 1705 (N-CO), 1597ꢀcm-1 (CN); 1H NMR (DMSO-d6): δ 1.58
(d, 3H, CH3, J = 7 Hz), 1.87 (t, 2H, CH2, J = 6 Hz), 2.80 (m, 4H, 2CH2),
3.81 (s, 3H, OCH3), 3.99 (q, 1H, SCH, J = 7 Hz), 6.66 (s, 1H, ArH), 6.75
(d, 1H, ArH, J = 9 Hz), 8.08 (d, 1H, ArH, J = 9 Hz); 13C NMR (DMSO-d6):
δ 181.7 (CO), 165.5 (CN), 164.9 (C-OCH3), 147.2, 131.7, 130.1, 117.9,
117.3 (ArC), 60.0 (OCH3), 34.9 (SCH), 34.9 (CH2), 32.0 (CH2), 27.0 (CH2),
24.1 (CH3); MS: m/z 304 (M+H+, 100%). Anal. Calcd for C15H17N3O2S:
C, 59.40; H, 5.61; N, 13.86; S, 10.56. Found: C, 59.49; H, 5.69; N, 13.91;
S, 10.86.
Acknowledgments: The authorities of Sant Longowal
Institute of Engineering and Technology, Longowal, India
are gratefully acknowledged for providing the research
facilities.
Received December 20, 2012; accepted December 28, 2012
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