Copper-catalyzed Mannichreactions of terminal alkynes and secondary amines with aqueous formaldehyde can be accelerated by the use of a catalytic amount of an imidazole ligand carrying a long alkyl chain. The alkyl chain shows an efficient steric effect and helps the reaction. This imidazole ligand is efficient for various substrates, including even bulky alkynes.
MIL-101 supported highly active single-site metal catalysts for tricomponent coupling
作者:Weng-Jie Sun、En-Qing Gao
DOI:10.1016/j.apcata.2018.10.020
日期:2019.1
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.