A practical, two-step synthesis of 1-alkyl-4-aminopyrazoles

A novel synthesis of N1 alkyl-substituted pyrazoles with a free amino group at the C4 position is described. Commercially available 4-nitropyrazole was found to readily undergo Mitsunobu reactions with primary and secondary alcohols. Subsequent reduction of the nitro group via hydrogenation affords 1-alkyl-4-aminopyrazoles, which are valuable intermediates in the synthesis of pharmaceutically active compounds.