Chlorosulfonic acid → 4-[2-(Acetylamino)-4-methyl-1,3-thiazol-5-yl]-5-bromothiophene-2-sulfonylchloride

Participants

Reaction Conditions

Reaction Steps

A mixture of N-[5-(2-bromo-thiophen-3-yl)-4-methyl-thiazol-2-yl]-acetamide obtained in Step II, as describe above (1100 mg; 3.47 mmol; 1 eq), in DCM (60 ml) is cooled to 0° C. with an ice bath. The reaction is degassed with nitrogen and chlorosulfonic acid (1.16 ml; 17.3 mmol; 5 eq) dissolved in DCM (30 ml) is added dropwise. The reaction mixture is stirred at 0° C. for 15 minutes. Phosphorus pentachloride (1444 mg; 6.94 mmol; 2 eq) is added followed directly by phosphorus oxide chloride (1.3 ml; 13.9 mmol; 4 eq). The reaction is stirred for an additional 2 hours at room temperature. Then the reaction mixture is poured into a beaker with crushed ice and directly transferred in a separated funnel. It is extracted with 2 portions EtOAc. The organic layer is dried over MgSO4, affording the title compound (1440 mg; quantitative yield).

Provenance & Evidence