Catalyst-Free Synthesis of 2-Arylbenzothiazoles in an Air/DMSO Oxidant System

Abstract

A straightforward strategy for the synthesis of 2-arylbenzothiazoles from 2-aminothiophenol and aryl aldehydes in air/DMSO oxidant system has been developed. This reaction is operationally simple, proceeds without catalysts, tolerates a wide range of functionalities, and provides desired products in good to excellent yields.

Key words

catalyst-free - 2-arylbenzothiazoles - air - DMSO

• References and Notes

• 1a Mortimer CG, Wells G, Crochard JP, Stone EL, Bradshaw TD, Stevens MF, Westwell AD. J. Med. Chem. 2006; 49: 179
• 1b Bénéteau V, Besson T, Guillard J, Léonce S, Pfeiffer B. Eur. J. Med. Chem. 1999; 34: 105
• 1c Chakraborty M, Jin KJ, Brewer SC, Peng H.-L, Platz MS, Novak M. Org. Lett. 2009; 11: 4862
• 1d Le Bozec L, Moody CJ. Aust. J. Chem. 2009; 62: 639
• 2 Bondock S, Fadaly W, Metwally MA. Eur. J. Med. Chem. 2010; 45: 3692
• 3 Gupta A, Rawat S. J. Chem. Pharm. Res. 2010; 2: 244
• 4 Rana A, Siddiqui N, Khan SA, Haque SE, Bhat MA. Eur. J. Med. Chem. 2008; 43: 1114
• 5a Sun Y, Jiang H, Wu W. Org. Lett. 2013; 15: 1598
• 5b Rezazadeh S, Akhlaghinia B, Razavi N. Aust. J. Chem. 2015; 68: 145
• 5c Luan Y, Zheng N, Qi Y. Eur. J. Inorg. Chem. 2014; 26: 4268
• 5d Paul S, Nanda P, Gupta R. Molecules 2003; 8: 374
• 5e Sakamoto T, Mori K, Akiyama T. Org. Lett. 2012; 14: 3312
• 6a Riadi Y, Mamouni R, Azzalou R, Haddad ME, Routier S, Guillaumet G, Lazar S. Tetrahedron Lett. 2011; 52: 3492
• 6b Dhakshinamoorthy A, Kanagaraj K, Pitchumani K. Tetrahedron Lett. 2011; 52: 69
• 6c Banerjee S, Payra S, Saha A. Tetrahedron Lett. 2014; 55: 5515
• 6d Shelkar R, Sarode S, Nagarkar J. Tetrahedron Lett. 2013; 54: 6986
• 6e Khalafi-Nezhad A, Panahi F, Yousefi R. J. Iran Chem. Soc. 2014; 11: 1311
• 6f Das S, Samanta S, Maji SK. Tetrahedron Lett. 2013; 54: 1090
• 6g Shelkar R, Sarode S, Nagarkar J. Tetrahedron Lett. 2013; 54: 6986
• 7a Ghashang M. Res. Chem. Intermed. 2014; 40: 1669
• 7b Yang Z, Chen X, Wang S. J. Org. Chem. 2012; 77: 7086
• 7c Sung G, Lee I, Bo RK. Tetrahedron 2013; 69: 3530
• 7d Bahrami K, Khodaei MM, Naali F. J. Org. Chem. 2008; 73: 6835
• 8a Soroko I, Bhole Y, Livingston AG. Green Chem. 2011; 13: 162
• 8b Tromov BA. Sulfur Rep. 1992; 74: 207
• 9a Zhou C, Larock RC. J. Org. Chem. 2006; 37: 3184
• 9b Vieira AA, Azeredo JB, Godoi M, Santi C, da Silva Júnior EM, Braga AL. J. Org. Chem. 2015; 80: 2120
• 9c Reddy MR, Rao NN, Ramakrishna K. Tetrahedron Lett. 2014; 55: 4758
• 10a Wu W, Jiang H. Acc. Chem. Res. 2012; 45: 1736
• 10b Vedernikov AN. Acc. Chem. Res. 2012; 45: 803
• 10c Campbell AN, Stahl SS. Acc. Chem. Res. 2012; 45: 851
• 10d Shi Z, Zhang C, Tang C, Jiao N. Chem. Soc. Rev. 2012; 41: 3381
• 10e Stahl SS. Science 2005; 309: 1824
• 10f Stahl SS. Angew. Chem. Int. Ed. 2004; 43: 3400
• 11 Naeimi H, Tarazian R. J. Heterocycl. Chem. 2014; 51: 566
• 12a Chusov D, List B. Angew. Chem. Int. Ed. 2014; 53: 5199
• 12b Kumará Verma P. Green Chem. 2013; 15: 1687
• 13 Shi X, Guo J, Liu J, Ye M, Xu Q. Chem. Eur. J. 2015; 21: 9988
• 14 Typical Procedure 2-Aminothiophenol (1a, 0.5 mmol, 1.0 equiv) and benzaldehyde (2a, 0.6 mmol, 1.2 equiv) were dissolved in DMSO (3 mL). Then, the reaction mixture was stirred at 60 °C for 6 h. After the reaction, H₂O was added to the mixture. The mixture was extracted with EtOAc (3 × 20 mL). The combined organic layers were then washed with sat. aq NaCl (30 mL). The solution was dried with anhydrous Na₂SO₄, filtered, and concentrated in vacuo. The crude residue was purified with silica gel chromatography (EtOAc–PE, 1:30) to give pure compound 3a in 96% yield. Selected Spectral Data for 2-Phenylbenzothiazole (3a) ¹H NMR (300 MHz, CDCl₃): δ = 8.07–8.12 (m, 3 H), 7.91 (d, J = 9.0 Hz, 1 H), 7.48–7.51 (m, 4 H), 7.39 (t, J = 9.0 Hz, 1 H).