4-broMo-2-cyanobenzene-1-sulfonyl chloride synthesis

Yield: 60%

Reaction Conditions:

Stage #1:5-amino-2-bromobenzonitrile with hydrogenchloride;acetic acid at 0; for 0.166667 h;
Stage #2: with sodium nitrite in water at 0; for 0.333333 h;Further stages;

Steps:

5.a; 6.a a.
4-bromo-3-cyano-benzenesulfonyl chloride
Solution-A: To a stirred solution of 5-amino-2-bromo-benzonitrile (2 g, 10.1 mmol) in AcOH (25 mL) was added conc. HCl (5 mL) at 0 °C and stirred for 10 minutes.
Then NaNO₂ (770 mg, 11.1 mmol) in H₂O (10 mL) was added at the same temperature and stirred for 20 minutes.
Solution-B: SO2 gas was purged in AcOH (25 mL) for 30 minutes.
Then a solution of CuCl₂ (1.62 g, 12.2 mmol) in H₂O (10 mL) was added at 0 °C and stirred for 20 minutes.
After that, Solution-B was added drop wise to Solution-A.
The reaction mixture was stirred at RT for 20 minutes and diluted with water (20 mL).
The resulting precipitate was filtered, washed with n-pentane (2 x 20 mL) and dried under high vacuum to afford a yellow solid (1.7 g, 60%).

References:

Antabio SAS;The designation of the inventor has not yet been filed EP3431474, 2019, A1 Location in patent:Paragraph 0165