Hydrochloric Acid → 3-Methyl-5-(2,2,2-trifluoroethoxy)-1,2-thiazole-4-sulfonyl chloride

Participants

Reaction Conditions

Reaction Steps

5 ml of acetic acid, 6 ml of 85% phosphoric acid, and 3 ml of concentrated hydrochloric acid was added to 2.1 g of 4-amino-3-methyl-5-(2,2,2-trifluoroethoxy)isothiazole prepared in the above step (2). 2 ml of aqueous solution containing 0.77 g of sodium nitrite was added dropwise to the above mixture at -20° to -10° C. The resulted solution was stirred at -5° C. for 30 minutes and was gradually added dropwise at -10° to -5° C. into 30 ml of an acetic acid solution, which had been saturated with sulfur dioxide and had contained 0.3 g of cuprous chloride. After the completion of dropping, the resulted solution was stirred and reacted at 0° to 5° C. for an hour. After the completion of the reaction, the reaction mixture was poured into ice-cold water, and was extracted with dichloromethane, and the extracted layer was sufficiently washed with water and dried. The solvent was subjected to distillation under reduced pressure to give 1.2 g of oily 3-methyl-5-(2,2,2-trifluoroethoxy)-4-isothiazolesulfonyl chloride.

Provenance & Evidence