Yield:69145-58-0 85%

Reaction Conditions:

with chlorosulfonic acid at 20 - 40; for 4 h;

Steps:

1

Intermediate (2) 2,4-Dichloro-3-bromomethyl-benzenesulfonyl chloride; 10 ml of chlorosulfonic acid are dropwise added with 4.8 ml of 2,6- dichlorotoluene in two hours, under magnetic stirring at room temperature. After completion of the addition, the mixture is heated at 4O⁰C for two hours, thereby obtaining a purple solution, which is cooled and carefully poured into ice-water (0.5 1), stirring vigorously. The separated white solid is filtered, triturated, washed with water, dried over KOH and purified by washing with n-hexane, adding 200 ml of solvent under strong stirring. The mixture is filtered, the solid is discarded and the solvent is evaporated to dryness to obtain 2,4-dichloro-3-methyl-benzenesulfonyl chloride as a crystalline white solid. Yield: 85%. HPLC purity: 86% (30% B, 3%/min, Rt=19.7 min).¹H-NMR (CDCl₃): δ (ppm) 2.6 (s, 3H), 7.5 (d, IH), 7.95 (d, IH); ESI(+)MS: m/z 260 [M+H]⁺.

References:

WO2006/40004,2006,A1 Location in patent:Page/Page column 9