The document summarizes the Buchwald-Hartwig coupling reaction and click reaction. The Buchwald-Hartwig reaction involves the coupling of an aryl halide and a primary or secondary amine in the presence of a base and palladium catalyst to form an aryl amine. The reaction proceeds by oxidative addition, substitution, and reductive elimination steps. The click reaction refers to the copper-catalyzed cycloaddition of an azide and alkyne to form a 1,2,3-triazole ring. This reaction has simple reaction conditions and provides products with high atom economy.