Lewis acid-catalyzed enantioselective Friedel-Crafts reaction of pyrazole-4,5-diones withβ-naphthol

A series of pyrazolone derivatives bearing a tetrasubstituted chiral center were prepared by virtue of a Lewis acid-catalyzed Friedel-Crafts reaction,in which a chiral copper complex was employed as the catalyst.This reaction can be carried out smoothly under mild condition to afford the pyrazolone derivatives with high yields(up to 85%)and excellent enantioselectivities(up to 99%).In addition,the gram scale synthesis proved the practicality of this reaction.