P. K. Mohanta et al. / Tetrahedron 56 (2000) 629–637
635
2-Oxazolidinethione (7). 0.82 g, 80% (0.92 g, 89%); Color-
less solid (ethanol); mp 97–98ЊC (lit. mp 98–99ЊC);36 IR
1-(20-Pyridyl)-3-phenylthiourea (8d). 2.04 g, 89% (2.08 g,
91%); Colorless solid (ethanol–water); mp 167–168ЊC (lit.
mp 167ЊC);39 IR (KBr): 3217, 1596, 1529, 1468, 1188,
(KBr): 3211, 1525, 1397, 1169, 913 cmϪ1 1H NMR
;
1
(300 MHz, CDCl3): d 8.18 (br s, 1H, NH), 4.73 (t,
J9.0 Hz, 2H, CH2), 3.85 (t, J9.0 Hz, 2H, CH2); 13C
NMR (75 MHz, CDCl3): d 190.26, 70.42, 44.19; MS (m/z,
%): 104 (Mϩϩ1, 92), 103 (Mϩ, 100); Anal. calcd for
C3H5NOS (103.15): C 34.93, H 4.89, N 13.58%; found: C
34.73, H 4.71, N 13.53%.
1140 cmϪ1; H NMR (400 MHz, CDCl3): d 13.69 (br s,
1H, NH), 9.68 (br s, 1H, NH), 8.21 (d, J4.8 Hz, 1H,
ArH), 7.67–7.63 (m, 3H, ArH), 7.42–7.39 (m, 2H, ArH),
7.26–7.23 (m, 1H, ArH), 7.02–6.96 (m, 2H, ArH); 13C
NMR (100.4 MHz, CDCl3): d 178.66, 153.40, 145.45,
138.74, 129.40 128.59, 126.14, 125.00, 118.04, 112.65;
MS (m/z, %): 229 (Mϩ, 84), 94 (98), 77 (63); Anal. calcd
for C12H11N3S (229.31): C 62.85, H 4.84, N 18.32%; found:
C 62.79, H 4.78, N 18.36%.
General procedure for the preparation of unsym-
metrical thioureas (8a–n)
1-Methyl-3-phenylthiourea (8e). 1.06 g, 64% (1.56 g, 94%);
Colorless solid (ethanol); mp 153–154ЊC (lit. mp 154–
157ЊC);16a IR (KBr): 3252, 3157, 2985, 1522, 1364, 1256,
In a typical experiment, a solution (or suspension) of 1
(1.58 g, 0.01 mol), or its salt 2 (3.0 g, 0.01 mol), and a
primary amine (0.01 mol) in absolute ethanol (30 mL) was
refluxed for 0.5–1.5 h. After disappearance of the amine
(monitored by TLC), a solution of the second amine
(0.01 mol), or ammonia solution (25%, 1 mL), in ethanol
(20 mL) was added. The reaction mixture was refluxed for
the stated time, then worked up as described for symmetrical
thioureas.
1
1035 cmϪ1; H NMR (400 MHz, CDCl3): d 8.21 (br s, 1H,
NH), 7.44–7.22 (m, 5H, ArH), 6.08 (br s, 1H, NH), 3.13 (d,
J4.6 Hz, 3H, NCH3); 13C NMR (100.4 MHz, CDCl3): d
181.60, 136.31, 130.16, 127.24, 125.39, 32.06; MS (m/z,
%): 167 (Mϩϩ1, 35), 166 (Mϩ, 100), 133 (50), 93 (99);
Anal. calcd for C8H10N2S (166.25): C 57.80, H 6.06, N
16.85%; found: C 57.78, H 6.18, N 16.72%.
For the synthesis of 8m and 8n the reagent 1 or 2 was first
reacted with ammonia solution (25%, 1 mL, 0.013 mol) at
room temperature, followed by treatment with secondary
amines (0.01 mol) and further refluxing in ethanol.
1-Cyclohexyl-3-phenylthiourea (8f). 1.52 g, 65% (1.92 g,
82%); Colorless solid (ethanol); mp 152–153ЊC (lit. mp
150–151ЊC);16a (KBr): 3311, 3240, 2929, 2854, 1554,
1
1452, 1292, 1190, 1064, 927 cmϪ1; H NMR (400 MHz,
CDCl3): d 7.65 (br s, 1H, NH), 7.47–7.38 (m, 2H, ArH),
7.34–7.26 (m, 1H, ArH), 7.22–7.15 (m, 2H, ArH), 5.90 (br
s, 1H, NH), 4.26 (br s, 1H, NHCH), 2.10–1.98 (m, 2H),
1.77–1.58 (m, 3H), 1.46–1.32 (m, 2H), 1.28–1.07 (m,
3H); 13C NMR (100.4 MHz, CDCl3): d 184.61, 136.09,
130.25, 127.20, 125.09, 54.18, 32.75, 25.42, 24.70; MS
(m/z, %): 234 (Mϩ, 62), 151 (72), 93 (100); Anal. calcd
for C13H18N2S (234.36): C 66.62, H 7.74, N 11.95%;
found: C 66.56, H 7.71, N 11.89%.
1-Benzyl-3-phenylthiourea (8a). 1.82 g, 75% (2.23 g,
92%); Colorless solid (ethanol–water); mp 165–166ЊC
(lit. mp 162–164ЊC);16a IR (KBr): 3363, 3145, 2974,
1
1541, 1504, 1301, 1245, 1178, 1066, 970 cmϪ1; H NMR
(400 MHz, CDCl3): d 8.18 (br s, 1H, NH), 7.40–7.20 (m,
10H, ArH), 6.25 (br s, 1H, NH), 4.85 (d, J5.4 Hz, 2H,
CH2Ar); 13C NMR (100.4 MHz, CDCl3): d 180.78,
137.21, 136.07, 130.50, 128.65, 127.54, 125.10, 49.30;
MS (m/z, %): 242 (Mϩ, 62), 106 (53), 91 (98); Anal. calcd
for C14H14N2S (242.34): C 69.39, H 5.82, N 11.56%; found:
C 69.45, H 5.91, N 11.77%.
1-Benzyl-3-cyclohexylthiourea (8g). 1.51 g, 61% (2.38 g,
96%); Colorless solid (ethanol); mp 91–92ЊC (lit. mp 93–
94ЊC);40 IR (KBr): 3309, 3238, 2927, 2852, 1552, 1540,
1-Phenethyl-3-phenylthiourea (8b). 1.87 g, 73% (2.38 g,
93%); Colorless solid (ethanol); mp 106–107ЊC (lit. mp
106ЊC);37 IR (KBr): 3371, 3021, 1536, 1494, 1350, 1263,
1
1512, 1491, 1304, 1212, 1197 cmϪ1; H NMR (400 MHz,
CDCl3): d 7.38–7.26 (m, 5H, ArH), 6.16 (br s, 1H, NH),
5.79 (br s, 1H, NH), 4.63 (br s, 2H, ArCH2), 3.84 (br s, 1H,
HNCH), 1.98–1.90 (m, 2H), 1.68–1.54 (m, 3H), 1.39–1.27
(m, 2H), 1.20–1.08 (m, 3H); 13C NMR (100.4 MHz,
CDCl3): d 180.59, 136.97, 128.95, 127.95, 127.56, 52.99,
48.43, 32.71, 25.33, 24.53; MS (m/z, %): 248 (Mϩ, 52), 106
(39), 91 (100); Anal. calcd for C14H20N2S (248.39): C 67.70,
H 8.12, N 11.28%; found: C 67.67, H 8.04, N 11.19%.
1
1000 cmϪ1; H NMR (400 MHz, CDCl3): d 7.77 (br s, 1H,
NH), 7.34–6.97 (m, 10H, ArH), 5.95 (br s, 1H, NH), 3.89 (q,
J7.0 Hz, 2H, HNCH2), 2.93 (t, J7.0 Hz, 2H, CH2); 13C
NMR (100.4 MHz, CDCl3): d 181.60, 138.47, 135.92,
130.13, 128.77, 127.19, 126.67, 125.19, 46.38, 34.84; MS
(m/z, %): 256 (Mϩ, 84), 152 (81), 151 (100), 93 (88); Anal.
calcd for C15H16N2S (256.38): C 70.27, H 6.29, N 10.93%;
found: C 70.13, H 6.32, N 11.05%.
1,10-Dimethyl-3-phenylthiourea (8h). 1.42 g, 79% (1.69 g,
94%); White solid (ethanol); mp 137–138ЊC (lit. mp 137–
138ЊC);16a IR (KBr): 3271, 2927, 1598, 1494, 1375, 1253,
1-(40-Methoxyphenyl)-3-phenylthiourea (8c). 1.91 g, 74%
(2.22 g, 86%); Colorless solid (ethanol–water); mp 142–
143ЊC (lit. mp 143ЊC);38 IR (KBr): 3250, 2960, 2835,
1
1137, 935 cmϪ1; H NMR (400 MHz, CDCl3): d 7.34–7.14
(m, 6H, ArH, NH), 3.28 (s, 6H, (CH3)2); 13C NMR
(100.4 MHz, CDCl3): d 182.57, 139.85, 128.64, 125.36,
124.54, 41.47, 41.39; MS (m/z, %): 180 (Mϩ, 59), 179 (38),
147 (48), 88 (69); Anal. calcd for C9H12N2S (180.27): C
59.97, H 6.71, N 15.54%; found: C, 60.01, H 6.90, N 15.61%.
1546, 1506, 1463, 1333, 1246, 1033 cmϪ1 1H NMR
;
(400 MHz, DMSO-d6): d 9.41 (br s, 2H, NH), 7.33–7.30
(m, 5H, ArH), 6.94–6.88 (m, 4H, ArH), 3.34 (s, 3H, OMe);
13C NMR (100.4 MHz, DMSO-d6): d 180.19, 156.49,
139.39, 132.22, 128.36, 126.07, 123.64, 113.62, 55.20;
MS (m/z, %): 258 (Mϩ, 14), 123 (73), 108 (100); Anal.
calcd for C14H14N2OS (258.34): C 65.09, H 5.46, N
10.84%; found: C 65.12, H 5.53, N 10.97%.
N-Benzyl-1-piperidinethiocarbamide (8i). 2.04 g, 87%
(2.25 g, 96%); White solid (ethanol); mp 86–87ЊC (lit. mp