2-BenzothiazolaMine, 5,7-dibroMo- synthesis

Yield:1000289-40-6 98%

Reaction Conditions:

Stage #1: N-[3,5-dibromophenyl]thioureawith bromine in chloroform at -60 - 75; for 4.25 h;Heating / reflux;
Stage #2: with ammonia in water; pH=10 - 12; for 0.5 h;

Steps:

1.A.5

5,7-Dibromo-benzothiazol-2-ylamine.To a solution of (3,5-dibromo-phenyl)-thiourea (35 g, 0.11 mol) in CHCI₃ (600 mL) at -55-6O⁰C was added dropwise a solution of Br₂ (40.40 g, 0.25 mol, in 100 ml of CHCI₃) over a period of 1 h. The reaction mixture was stirred at -55-6O⁰C for 15 min followed by refluxing at 70-75⁰C for 3 h. The reaction mixture was cooled to room temperature and filtered to get the crude residue that was washed with hexane and diethyl ether. The solid thus obtained was dissolved in H₂O, basified with aqueous ammonia solution to pH 10-12 and stirred for 30 min. The solid thus obtained was filtered and washed with water to get the desired product (34.0 g, 98%). ¹H-NMR (400 MHz, DMSO-d₆): δ 7.39 (s, 1 H), 7.48 (s, 1 H) and 7.95 (br s, 2H). MS: 308.96 (M+H)⁺.

References:

WO2007/148093,2007,A1 Location in patent:Page/Page column 18-19