Polymer-supported acylhydrazones. Use in Sc(OTf)3-catalyzed Mannich-type reactions providing an efficient method for the preparation of diverse pyrazolone derivatives

Abstract Polymer-supported acylhydrazones, prepared from polystyrene resin (1%-divinylbenzene), reacted with ketene silyl acetals in the presence of a catalytic amount of scandium triflate (Sc(OTf) 3 ), to afford the corresponding β-hydrazinoesters, which were cyclized and cleaved from the support simultaneously by treatment with a base to produce diverse pyrazolone derivatives.