Methyl (5-oxopyrazol-3-yl)acetate N,S-ketene acetal as a new building block for the construction of pyrazolo[4,3-c]pyridines

Abstract

Methyl (5-oxopyrazol-3-yl)acetate is added to methylthiocyanate C≡N bond in the presence of Ni(OAc)₂ giving a corresponding heterocyclic N,S-ketene acetal. The latter compound was used as a convenient synthon in the synthesis of new pyrazolo[4,3-c]pyridin-3-ones and pyrazolo[4,3-c]pyridine-3,6-diones.