Syntheses of 5-Arylpyrazole Derivatives via Palladium-catalyzed Cross-Coupling Reactions

Abstract

The first examples of a direct introduction of an aryl group onto a pyrazole ring via palladium-catalyzed cross-coupling reactions are reponed.It w,as found that substituents at 1position on the pyrazole ring affected the yields.and dimethylsulfamoyl group, as an electronwithdrawing group.gave highest yield.Recently, considerable attention is being paid to the direct introduction of an aryl group onto nitrogencontaining heteroaromatics, such as ~yridine,l-~ pyrimidine4 and imidaz0le,~.6 as a method for construction of natural products3,5 or pharma~euticals.~,~The key reactions to build up these molecules are