7-Benzothiazolecarboxylicacid,ethylester(9CI) synthesis

Yield:677304-90-4 71%

Reaction Conditions:

with isopentyl nitrite in tetrahydrofuran; for 4 h;Heating / reflux;

Steps:

89

iso-amylnitrite (7.4 mL, 53 mmol, 2.2 eqiv) was added to a solution of ethyl 2-amino-1,3-benzothiazole-7-carboxylate (5.40 g, 24.3 mmol) in tetrahydrofuran (70 mL) and the mixture was heated at reflux for 4 h. The volatiles were removed under reduced pressure and the residue was purified by chromatography (0/100 to 5/95 methanol/dichloromethane) to provide 3.56 g (71%) of the ester. 1H NMR (500 MHz, CDCl3) & δ 1.47 (t, J= 7.5, 3H), 4.49 (q, J= 7, 2H), 7.62 (t, J= 8, 1H), 8.20 (d, J= 6.5, 1H), 8.33 (d, J= 8, 1H), 9.12 (s, 1H); MS (EI) m/z 208 (M+ +1)

References:

WO2004/29050,2004,A1 Location in patent:Page 69