A general and efficient synthesis of pyrazoles catalyzed by Sc(OTf)3 under solvent-free conditions

Abstract

Pyrazoles were prepared in excellent yields via solventless condensation of various 1,3-diketones (R1COCHXCOCH3, R1 = Me, Ph; X = H, Me, Cl) and hydrazines, acylhydrazines or sulfonyl hydrazines in the presence of a catalytic amount of Sc(OTf)3 at room temperature. Additionally, the catalyst could be recovered easily after the reactions and reused without evident loss in activity. ©2009 Sociedade Brasileira de Química.