Synthesis of 3-(2-benzyloxy-6-hydroxyphenyl)-1-methylpyrazoles by the reaction of chromones with methylhydrazine

The 3-(2-benzyloxy-6-hydroxyphenyl)-5-(methyl, phenyl or styryl)pyrazoles were prepared from the reaction of 2-(methyl, phenyl or styryl)chromones with methylhydrazine. The structure of these compounds has been determined by several nmr techniques, and the reaction mechanism is discussed.