A solution of hydroxy-(4-methoxy-phenyl)-acetic acid [1-(4-hydroxy-3-methoxy-phenyl)-meth-(E)-ylidene]-hydrazide (21 g, 63 mmol) in 500 ml of ethanol is hydrogenated under atmospheric pressure with hydrogen and a mixture of 5% of palladium on charcoal (10.5 g) as catalyst. The reaction is stirred for 6 hours at room temperature. Subsequently, the mixture is filtered under argon and the solvent is evaporated to yield hydroxy-(4-methoxy-phenyl)-acetic acid N′-(4-hydroxy-3-methoxy-benzyl)-hydrazide as colourless tarr.
