Nitropyrazoles 16. The use of methoxymethyl group as a protecting group for the synthesis of 4-methyl-3-nitro-5-R-pyrazoles

4-Methyl-3,5-dinitropyrazole prepared by nitration of 1,4-dimethylpyrazole readily reacts with methoxymethyl chloride and methyl vinyl ketone in acetonitrile in the presence of a base giving 1-methoxymethyl-4-methyl-3,5-dinitropyrazole and 4-methyl-3,5-dinitro-1-(3-oxobutyl)pyrazole, respectively. The action of the thioglycolanilide anion on 4-methyl-3,5-dinitro-1-(3-oxobutyl)pyrazole results only in the removal of 1-protecting group and the formation of 2-[(3-oxobutyl)thio]acetanilide, while the action of anionic S-nucleophiles on 1-methoxymethyl-4-methyl-3,5-dinitropyrazole leads to the substitution products of the 5-NO2 group in which the methoxymethyl group can be removed by acid hydrolysis.