POLYFUNCTIONAL PYRAZOLES. 9*. SYNTHESIS OF 1-ALKYL(ARYL)-3-[4-(HYDROXYMETHYL)-1Н-PYRAZOL-3-YL]UREAS

Abstract

We have developed an effective method for the preparation of 1-alkyl(aryl)-3-[4-(hydroxymethyl)-1Н-pyrazol-3-yl]ureas based on the interaction of 4-hydroxymethylpyrazole-3-carbonyl azides with primary aliphatic and aromatic amines under the conditions of Curtius reaction. In the absence of amines in the reaction mixture, in situ generated 4-hydroxymethyl-3-isocyanatopyrazoles underwent intramolecular cyclization to pyrazolo[3,4-d][1,3]oxazin-6(4Н)-ones. The latter showed a tendency to form 1-alkyl(aryl)-3-[4-(hydroxymethyl)-1Н-pyrazol-3-yl]ureas in the presence of amines.