3-Acylaminopyrazole derivatives via a regioselectively N-protected 3-nitropyrazole

A simple procedure for the selective protection of the enclocyclic 1-N of 3-aminopyrazoles as tert-butoxycarbamate (Boc) in good yield is described. A 3-nitropyrazole derivative represents the key intermediate with the nitro substituent determining the regiochemistry of the obtained protected Compound. Subsequent acylation at the exocyclic amino group gave rise, after Bee removal, to a series of 3-acylaminopyrazoles in high yields and purities. (C) 2004 Elsevier Ltd. All rights reserved.