N‐N migration of a carbamoyl group in a pyrazole derivative revealed by NMR

Abstract

During a synthesis of 5-amino-4-(6-methoxy-2-methylpyridin-3-yl)-3-methyl-1H-pyrazole-1-carboxamide (see Scheme 1), a side-reaction produced 3-amino-4-(6-methoxy-2-methylpyridin-3-yl)-5-methyl-1H-pyrazole-1-carboxamide as a by-product that forms an equilibrium with the target-compound. The structure of the by-product was elucidated by the interpretation of 1D and 2D (HMQC, HMBC) NMR data where (1)H-(15)N HMBC correlations revealed the position of carbamoyl group attachment on the pyrazole. Comparison of structures of the target-compound and the by-product showed that the latter resulted from N-N migration of the carbamoyl group in the target-compound.