A Novel System for the Synthesis of 2-Aminobenzthiazoles using Sodium Dichloroiodate

Vikas N. Telvekar; Harshal M. Bachhav; Vinod Kumar Bairwa

doi:10.1055/s-0032-1317080

Synlett, Table of Contents

Synlett 2012; 23(15): 2219-2222
DOI: 10.1055/s-0032-1317080

letter

A Novel System for the Synthesis of 2-Aminobenzthiazoles using Sodium Dichloroiodate

Vikas N. Telvekar*

Department of Pharmaceutical Sciences & Technology, Institute of Chemical Technology, Matunga, Mumbai 400 019, India, Fax: +91(22)24145614 Email: vikastelvekar@rediffmail.com

,

Harshal M. Bachhav

Department of Pharmaceutical Sciences & Technology, Institute of Chemical Technology, Matunga, Mumbai 400 019, India, Fax: +91(22)24145614 Email: vikastelvekar@rediffmail.com

,

Vinod Kumar Bairwa

Department of Pharmaceutical Sciences & Technology, Institute of Chemical Technology, Matunga, Mumbai 400 019, India, Fax: +91(22)24145614 Email: vikastelvekar@rediffmail.com

› Author Affiliations

Abstract

All articles of this category

Abstract

2-Aminobenzthiazole is a privileged scaffold with a range of biological activities. However, to date, an efficient protocol for the synthesis of this ring system using aniline as a starting material has been lacking. Herein, for the first time, we describe a highly efficient and mild protocol for the synthesis of 2-aminiobenzthiazole using NaICl₂.

Key words

synthetic methods - oxidative cyclization - sodium dichloroiodate - aniline - aminobenzthiazole

Full Text

References

References and Notes
1 Suter H, Zutter H. Helv. Chim. Acta 1967; 50: 1084
2 He Y, Benz A, Fu T, Wang M, Covey DF, Zorumski CF, Mennick S. Neuropharmacology 2002; 42: 199
3 Sawhney SN, Arora SK, Singh JV, Bansal OP, Singh SP. Indian J. Chem., Sect. B: Org. Chem. Incl. Med. Chem. 1978; 16: 605
4 Bensimon G, Lacomblez L, Meininger V. New Engl. J. Med. 1994; 330: 585
5 Foscolos G, Tsatsas G, Champagnac A, Pommier M. Ann. Pharm. Fr. 1977; 35: 295
6 Shirke VG, Bobade K, Bhamaria RP, Khadse BG, Sengupta SR. Indian Drugs 1990; 27: 350

7a Bradshaw TD, Wrigley S, Shi DF, Schulz RJ, Paull KD, Stevens MF. G. Br. J. Cancer 1998; 77: 745
7b Hutchinson I, Chua MS, Browne HL, Trapani V, Bradshaw TD, Westwell AD, Stevens MF. G. J. Med. Chem. 2001; 44: 1446

8 Paget CJ, Kisner K, Stone RL, Delong DC. J. Med. Chem. 1969; 12: 1016

9a Bose DS, Idrees M. Tetrahedron Lett. 2007; 48: 669
9b Bose DS, Idrees M. J. Org. Chem. 2006; 71: 8261
9c Downer-Riley NK, Jackson YA. Tetrahedron 2008; 64: 7741
9d Xian H, Jing T. Tetrahedron 2003; 59: 4851
9e Garin J, Melendez E, Merchan FL, Merino P, Orduna J, Tejero T. Synth. Commun. 1990; 20: 2327

10a Vera MD, Pelletier JC. J. Comb. Chem. 2007; 9: 569
10b Spatz JH, Bach T, Umkehrer M, Bardin J, Ross G, Burdack C, Kolb J. Tetrahedron Lett. 2007; 48: 9030
10c Evindar G, Batey RA. J. Org. Chem. 2006; 71: 1802
10d Joyce LL, Evindar G, Batey RA. Chem. Commun. 2004; 4: 446
10e Benedi C, Bravo F, Uriz P, Fernandez E, Claver C, Castillon S. Tetrahedron Lett. 2003; 44: 6073

11a Joyce LL, Batey RA. Org. Lett. 2009; 11: 2792
11b Inamoto K, Hasegawa C, Hiroya K, Doi T. Org. Lett. 2008; 10: 5147

12a Bernardi D, Ba LA, Kirsch G. Synlett 2007; 2121
12b Ding Q, Huang X.-G, Wu J. J. Comb. Chem. 2009; 11: 1047

13a Tour JM, Kosynkin DV. Org. Lett. 2001; 3: 991
13b Hajipour AR, Arbabian M, Ruoho AE. J. Org. Chem. 2002; 67: 8622

14a Telvekar VN, Jadhav NC. Synth. Commun. 2008; 38: 3107
14b Telvekar VN, Patel KN, Kundaikar HS, Chaudhari HK. 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) 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. 6-Methyl-1,3-benzothiazol-2-amine (Table 3, entry 2) 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. 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

16a Ramana T, Saha P, Das M, Punniyamurthy T. Org. Lett. 2010; 12: 84
16b Hrobarik P, Hrobarikova V, Sigmundova I, Zahradnik P, Fakis M, Polyzos I, Persephonis P. J. Org. Chem. 2011; 76: 8726
16c Cossey HD. J. Chem. Soc. 1965; 954
16d Li Z, Xiao S, Tian G, Zhu A, Feng X, Liu J. Phosphorus, Sulfur Silicon Relat. Elem. 2008; 183: 1124
16e Jimonet P, Audiau F, Barreau M, Blanchard J.-C, Boireau A. J. Med. Chem. 1999; 42: 2828
16f Inoue H, Konda M, Hashiyama T, Otsuka H, Watanabe A. Chem. Pharm. Bull. 1997; 45: 1008