* All experimental methods are cited from the reference, please refer to the original source for details. We do not guarantee the accuracy of the content in the reference.
A mixture OF 5-NITRO-1, 3-benzothiazole (Description 5,1. 9 g, 11 mmol) and tin (II) chloride dihydrate (8.6 g, 38 mmol) in 2-propanol (30 ml) was heated to reflux for 24 h. The cooled reaction mixture was poured onto an ice/water mixture (85 ml) and adjusted to pH7 with sodium hydroxide (s). The mixture was extracted with ethyl acetate (3 X 50 ml) and the combined organic layers were dried over sodium sulfate, filtered and evaporated. The residue was purified by column chromatography on silica (eluant 1 : 1 hexane: ethyl acetate) to give 1, 3-benzothiazol-5-amine (820 mg, 52 %). LHNMR (CDCL3) 6 6.85 (1H, dd, J2. 3,8. 6), 7.40 (1H, d, J2. 1), 7.66 (1H, d, J 8.4), 8.90 (1H, s).
With stannous chloride;
5-Aminobenzothiazole To a solution of SnCl2 (7.0 g, 8.8 mmol) and 14 mL of con.HCl was added 5-nitrobenzothiazole (0.65 g, 3.6 mmol) in a portion and resulting reaction mixture was stirred for 1 h at 25 C. The reaction mixture was basified with aqueous NaOH and extracted with EtOAc. Combined organic layers were dried over Na2 SO4 and concentrated in vacuo, yielding an oil (0.47 g, 3.2 mmol, 89%) which was identified as the amine (>95% pure) and subjected to the following reaction without further purification.
With hydrogen;palladium 10% on activated carbon; In tetrahydrofuran; methanol;
Step 9.2: 5-Amino-benzothiazole Purified 5-nitro-benzothiazole (7.2 g, 0.04 mol, see WO 98/23612, example 7A), dissolved in 160 mL of methanol and 160 mL of THF, is hydrogenated in the presence of 1.6 g Pd/C (10%; Engelhard 4505). The catalyst is filtered off, the filtrate concentrated and the residual oil purified by flash chromatography on silica gel using dichloromethanol/methanol 97:3 as eluent. The title compound is obtained as a colorless solid: m.p. 76-78 C., HPLC tR=0.76 min; MS-ES+: (M+H)+=151; Rf (dichloromethane/methanol 97:3)=0.76.
With hydrogen;10% palladium on activated carbon; In tetrahydrofuran; methanol;
Purified 5-nitro-benzothiazole (7.2 g, 0.04 mol, see WO 98/23612, example 7A), dissolved in 160 mL of methanol and 160 mL of THF, is hydrogenated in the presence of 1.6 g Pd/C (10 %; Engelhard 4505). The catalyst is filtered off, the filtrate concentrated and the residual oil purified by flash chromatography on silica gel using dichloromethanol/methanol 97:3 as eluent. The title compound is obtained as a colorless solid: m.p. 76-78 0C, HPLC tR = 0.76 min; MS-ES+: (M+H)+ = 151 ; Rf (dichloromethane/methanol 97:3) = 0.76.
5-Nitrobenzo[d]thiazole (150 mg) was dissolved in THF (20 mL) at 0 0C and AcOH (1 mL) was added followed by Zinc dust (1.65 g). Mixture was stirred at RT for 1 h and was filtered on silica pad (rinsed with EtOAc). Solvent was evaporated, residue was diluted with NaHCO3 and extracted with EtOAc. Organic phases was dried, filtered and evaporated to give benzo[d]thiazol-5-amine.
2.1 g
With tin(II) chloride dihdyrate; In ethyl acetate;Reflux;
A mixture of 5-nitrobenzo[d]thiazole (3.0 g, 16.7 mmol) and SnCl2*2H2O (19 g, 84.2 mmol) in EtOAc (150 mL) was stirred at reflux overnight. The reaction mixture was basified with Et3N until pH 8 and the precipitate was filtered. The filtrate was concentrated in vacuo and the residue was purified by column chromatography on silica gel (EtOAc/DCM = 2:1) to afford the title compound as a yellow solids (2.1 g). 1H NMR (400 MHz, CDCl3): oe 8.92 (s, 1H), 7.69 (d, 1H), 7.41 (d, 1H), 6.86 (dd, 1H), 3.82 (brs, 2H); LCMS: 151 (M+H).
B. 5-Aminobenzothiazole A mixture of 3.46 g of 5-nitrobenzothiazole and 15.7 g of stannous chloride dihydrate in 55 mL of 2-propanol is heated to reflux for 3 hours. The cooled reaction mixture is poured into 150 mL of ice/water and neutralized to pH 7 using solid sodium hydroxide. The mixture is extracted with ethyl acetate (3*50 mL). The combined organic layers are dried over sodium sulfate, filtered through a short pad of silica gel, and rotary evaporated to provide 2.45 g of 5-aminobenzothiazole as a yellow-brown solid.
Chemistry
Pharmaceutical Intermediates
Inhibitors/Agonists
Material Science
For Research Only
120K+ Compounds
Competitive Price
1-2 Day Shipping
