Abstract The reaction of substituted ethyl 5-aminopyrazole-4-carboxylates with two equivalents of methanesul-fonyl chloride gave the substituted ethyl 5-[bis (methylsufonyl) amino]-1H.-pyrazole-4-carboxylates II. Removal of one of the methanesulfonyl groups, followed by alkylation of the ethyl 5-[(methylsulfonyl) amino]-1H-pyrazole-4-carboxylates III with methyl iodide produced the substituted ethyl 5-[methyl (methylsulfonyl) amino]-1H- ...