2-Amino-6-benzothiazolol → 2-(4-Nitrophenyl)imidazo[2,1-b]benzothiazol-7-ol

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This product was prepared according to J. Med. Chem. 2009, 52, 7808-7816 with some modifications. A mixture of 2-amino-1,3-benzothiazol-6-ol (2.0 g, 12.18 mmol) and 2-bromo-4′-nitroacetophenone (2.97 g, 12.18 mmol) in IPA (40 ml) was heated to reflux for 24 h. The reaction mixture was then cooled to 0° C. and the resulting precipitate was filtrated and washed with IPA to afford 2-(4-nitrophenyl)imidazo[2,1-b][1,3]benzothiazol-7-ol (65% c.y.). To a DMF (52 ml) solution of 2-(4-nitrophenyl)imidazo[2,1-b][1,3]benzothiazol-7-ol was added potassium carbonate (2.94 g) and 4-(2-chloroethyl)morpholine hydrochloride (1.97 g). The reaction mixture was heated to 85° C. and stirred at the same temperature for 48 h. Then it was poured into water (100 ml), filtered and washed with water and ethyl ether to give 7-(2-morpholin-4-yl-ethoxy)-2-(4-nitrophenyl)imidazo[2,1-b][1,3]benzothiazole (86% c.y.). A mixture of 7-(2-morpholin-4-yl-ethoxy)-2-(4-nitrophenyl)imidazo[2,1-b][1,3]benzothiazole and ammonium chloride (0.77 g) in ethanol (50 ml) was heated to reflux, and then iron powder (3.0 g) was added. The mixture was refluxed for 5 h and then immediately filtered though Celite and washed with hot ethanol. The filtrate was concentrated, neutralized with saturated NaHCO3 solution and extracted with DCM. The organic solution was dried with Na2CO3 and the solvent was removed under reduced pressure to afford the desired product [4-(7-(2-morpholin-4-yl-ethoxy)imidazo[2,1-b]benzothiazol-2-yl]aniline (32% c.y.).

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