5-Methoxy-1-methyl-3-sulfinamoyl-1H-indole-2-carboxylic acid methyl ester 、
potassium permanganate 以
丙酮 、
水 为溶剂,
以33.7 gm (78% of theory) of methyl 5-methoxy-1-methyl-3-sulfamoyl-indole-2-carboxylate, M.p.: 190° C., and 7.4 gm (19% of theory) of 7-methoxy-4-methyl-2H-isothiazolo[4,5-b]indole-3(4H)-one-1,1-dioxide, M.p.: above 290° C. (decomposition), were obtained的产率得到methyl 5-methoxy-1-methyl-3-sulfamoyl-indole-2-carboxylate