Hydrogen Bromide → 2-Bromo-4-chlorobenzothiazole

Participants

Reaction Conditions

Reaction Steps

[(2-(4-Chlorobenzothiazotyl))carbonyl]-1-piperidinecarboxylic acid, 1,1-dimethylethyl ester ##STR29## Slurry 2-amino-4-chlorobenzothiazole (0.255 mol) in water (325 mL), heat to reflux and add 48% hydrobromic acid (130 mL). Maintain at reflux for 20 minutes, cool to 0° C. and add a solution of sodium nitrite (17.56 g, 0.255 mol) in water (90 mL), maintaining a temperature of 0° C. Stir at 0° C. for 15 minutes and add by dropwise addition (while keeping cold) to a rapidly stirring mixture of copper (I) bromide (42.03 g, 0.293 mol) in 48% hydrobromic acid (86 mL) and water (225 mL). Stir at room temperature for 20 minutes and then heat on a steam bath for an additional 20 minutes. Allow to stand overnight, extract into methylene chloride and dry (MgSO4). Evaporate the solvent in vacuo and purify by chromatography to give 2-bromo-4-chlorobenzothiazole.

Provenance & Evidence