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V. N. Telvekar et al.
LETTER
6-Methyl-1,3-benzothiazol-2-amine (Table 3, entry 2)
(d) Joyce, L. L.; Evindar, G.; Batey, R. A. Chem. Commun.
2004, 4, 446. (e) Benedi, C.; Bravo, F.; Uriz, P.; Fernandez,
E.; Claver, C.; Castillon, S. Tetrahedron Lett. 2003, 44,
6073.
Mp 132–133 °C (Lit.16b 135–137 °C); IR (KBr): 3373, 3285,
3072, 2934, 1637, 1535, 1458, 1374, 1302, 1107 cm–1. 1H
NMR (300 MHz, CDCl3): δ = 7.63–7.50 (m, 3 H), 5.49 (s,
2 H), 2.51 (s, 3 H). Anal. Calcd for C8H8N2S: C, 58.51; H,
4.91; N, 17.06. Found: C, 58.47; H, 4.93; N, 17.08.
4,5-Dichloro-1,3-benzothiazol-2-amine (Table 3, entry 8)
Mp 274–277 °C (Lit.16c 275–276 °C); IR (KBr): 3403, 3326,
3221, 1629, 1571, 1460, 1380, 810, 580 cm–1; 1H NMR
(300 MHz, CDCl3): δ = 7.48–7.36 (m, 2 H), 6.78 (s, 2 H).
Anal. Calcd for C7H4Cl2N2S: C, 38.37; H, 1.84; N, 12.79.
Found: C, 38.39; H, 1.85; N, 12.76.
(11) (a) Joyce, L. L.; Batey, R. A. Org. Lett. 2009, 11, 2792.
(b) Inamoto, K.; Hasegawa, C.; Hiroya, K.; Doi, T. Org.
Lett. 2008, 10, 5147.
(12) (a) Bernardi, D.; Ba, L. A.; Kirsch, G. Synlett 2007, 2121.
(b) Ding, Q.; Huang, X.-G.; Wu, J. J. Comb. Chem. 2009,
11, 1047.
(13) (a) Tour, J. M.; Kosynkin, D. V. Org. Lett. 2001, 3, 991.
(b) Hajipour, A. R.; Arbabian, M.; Ruoho, A. E. J. Org.
Chem. 2002, 67, 8622.
(14) (a) Telvekar, V. N.; Jadhav, N. C. Synth. Commun. 2008, 38,
3107. (b) Telvekar, V. N.; Patel, K. N.; Kundaikar, H. S.;
Chaudhari, H. K. Tetrahedron Lett. 2008, 49, 2179.
(15) General procedure for synthesis of 6-chloro-2-
aminobenzthiazole (Table 2, entry 1): To a stirred solution
of 4-chloroaniline (0.1 g, 0.78 mmol) and potassium
thiocyanate (0.53 g, 5.5 mmol) in DMSO–H2O (9:1 mL) was
added NaICl2 (2 M, 0.52 g, 2.3 mmol). The reaction mixture
was stirred vigorously at r.t. for 5 min, then the mixture was
heated to 70 °C and progress of the reaction was monitored
by TLC. The reaction was quenched with H2O (10 mL) and
extracted with EtOAc (3 × 10 mL). The organic phases were
separated and washed successively with 10% aq Na2S2O4
(2 × 10 mL), 10% aq NaHCO3 (2 × 15 mL), and finally with
H2O (2 × 20 mL). The organic layer was dried over
anhydrous Na2SO4, filtered and concentrated under reduced
pressure to give the crude product. Pure 6-chloro-2-
aminobenzthiozole was obtained as a yellow solid after
silica gel column chromatography (EtOAc–hexane, 80:20).
1,3-Benzothiazol-2-amine (Table 3, entry 1)
6-Nitro-1,3-benzothiazol-2-amine (Table 3, entry 11)
Mp 245–247 °C (Lit.16d 247–248 °C); IR (KBr): 3452, 3298,
3047, 1652, 1566, 1528, 1494, 1325 cm–1; 1H NMR (300
MHz, CDCl3): δ = 8.20–8.12 (m, 3 H), 5.90 (s, 2 H). Anal.
Calcd for C7H5N3O2S: C, 43.07; H, 2.58; N, 21.53. Found:
C, 43.02; H, 2.59; N, 21.57.
6-(Trifluoromethyl)-1,3-benzothiazol-2-amine (Table 3,
entry 14)
Mp 119–122 °C (Lit.16e 122 °C); IR (KBr): 3461, 3221,
1634, 1600, 1480, 1441, 1340, 1263, 1167, 1128 cm–1; 1H
NMR (300 MHz, CDCl3): δ = 7.70–7.62 (m, 3 H), 4.32 (s,
2 H).
4-Methoxy-1,3-benzothiazol-2-amine (Table 3, entry 17)
Mp 148–153 °C (Lit.16f 149–151 °C); IR (KBr): 3379, 3283,
3091, 2937, 1636, 1545, 1458, 1333, 1270, 1049 cm–1; 1H
NMR (300 MHz, CDCl3): δ = 7.37–7.10 (m, 3 H), 5.45–5.10
(br s, 2 H), 3.84 (s, 3 H). Anal. Calcd for C8H8N2OS: C,
53.31; H, 4.47; N, 15.54. Found: C, 53.26; H, 4.48; N, 15.58.
(16) (a) Ramana, T.; Saha, P.; Das, M.; Punniyamurthy, T.
Org. Lett. 2010, 12, 84. (b) Hrobarik, P.; Hrobarikova, V.;
Sigmundova, I.; Zahradnik, P.; Fakis, M.; Polyzos, I.;
Persephonis, P. J. Org. Chem. 2011, 76, 8726. (c) Cossey, H.
D. J. Chem. Soc. 1965, 954. (d) Li, Z.; Xiao, S.; Tian, G.;
Zhu, A.; Feng, X.; Liu, J. Phosphorus, Sulfur Silicon Relat.
Elem. 2008, 183, 1124. (e) Jimonet, P.; Audiau, F.; Barreau,
M.; Blanchard, J.-C.; Boireau, A. J. Med. Chem. 1999, 42,
2828. (f) Inoue, H.; Konda, M.; Hashiyama, T.; Otsuka, H.;
Watanabe, A. Chem. Pharm. Bull. 1997, 45, 1008.
Mp 127–129 °C (Lit.16a 129–130 °C); IR (KBr): 3402, 3266,
3052, 1637, 1525, 1442, 1306, 1102 cm–1; 1H NMR
(300 MHz, CDCl3): δ = 7.73–7.60 (m, 4 H), 5.70 (s, 2 H).
Anal. Calcd for C7H6N2S: C, 55.97; H, 4.03; N, 18.65.
Found: C, 55.99; H, 4.04; N, 18.62.
Synlett 2012, 23, 2219–2222
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