Metal-organic frameworks with regular pore structures provide powerful platforms for the design of single-site metal catalysts for chemical transformation. In this paper, we develop a facile, stable and recyclable MOF-supported Cu(II) catalyst, MIL-101-SO3Cu. It shows extremely high activity for the A(3) coupling of alkynes, aldehydes and amines. The turnover frequency can reach 6.8 x 10(5) h(-1) under neat conditions, which is the highest so far reported for the reaction. The high activity is because the specific structure of the MIL-101-SO3 support enables a single-site dispersion and an unhindered open environment for the metal ion. MIL-101-SO3Cu also exhibits high activity for the one-pot cascade reactions combining A(3) coupling and 5-endo-dig cyclization.