N-bromobutanimide → 5-Bromo-2-(bromomethyl)-1,3-benzothiazole

Participants

Reaction Steps

N-Bromosuccinimide (4.45 g, 25 mmol, 1.4 equiv.) and subsequently α,α′-azoisobutyronitrile (110 mg, 0.7 mmol, 0.04 equiv.) were added to a solution of 5-bromo-2-methyl-benzothiazole (4.07 g, 17.85 mmol, 1 equiv.) in CCl4 (110 ml). The reaction mixture was stirred at reflux for 24 hrs. After cooling, succinimide was removed by filtration and was rinsed with CCl4 (100 ml). The filtrate was evaporated to dryness under reduced pressure and the orange solid residue was purified by column chromatography on silica, eluted with CH2Cl2/hexane (20%-70% gradient), to give the desired product as a white solid, 2.15 g (39% yield). Mp 116-117, HPLC-MS (method 1): m/z 308 [M+H]+, Rt=4.84 min. The reaction gave also 1.40 g (20% yield) of the by-product 5-bromo-2-dibromomethyl-benzothiazole, as well as 0.89 g (22%) of un-reacted starting material.

Provenance & Evidence