Selektive Acylierungen von 3(5)‐Alkyl‐5(3)‐amino‐1 H ‐pyrazolen und eine neue Pyrazolo[5,1‐ c ]‐1,2,4‐triazol‐Synthese

Selective Acylations of 3(5)‐Alkyl‐5(3)‐amino‐1 H ‐pyrazoles and a New Pyrazolo[5,1‐ c ]‐1,2,4‐triazole Synthesis ( Z )‐5‐Amino‐1‐[1‐(hydroximino)alkyl]‐1 H ‐pyrazoles 3 have been synthesized by acylation of 3(5)‐alkyl‐5(3)‐amino‐1 H ‐pyrazoles 1 with nitrile oxides. The tosylation of the hydroxyimino group of 3 to ( Z )‐5‐amino‐1‐[1‐( p ‐tosyloximino)alkyl]‐1 H ‐pyrazoles 4 and the subsequent acetylation of the 5‐amino group give ( E )‐ and ( Z )‐5‐acetamido‐1‐[1‐( p ‐tosyloximino)alkyl]‐1 H ‐pyrazoles 5 , which undergo cyclization under basic conditions to pyrazolo[5,1‐ c ]‐1,2,4‐triazoles 6, 7 or 8 .