NMR-STUDY OF THE SOLID-STATE REARRANGEMENT OF 3-AMINO-1 AND 2-(CHLOROACETYL)PYRAZOLE TO 3-(CHLOROACETAMIDO)PYRAZOLE

Reaction of 3-aminopyrazole (1) with chloroacetyl chloride gives a mix ture of 3-amine-1- and -2-(chloroacetyl)pyrazole (2 and 3), both of wh ich rearrange in the solid-state to 3-(chloroacetamido)pyrazole (4) ov er a period of a few days. The course of the rearrangements was monito red directly by CP/MAS NMR and indirectly by H-1 NMR spectroscopy; the results suggest that the mechanism involves 3 --> 2 --> 4.