Constructing a synergistic catalyst by confining Pd within a MOF using an extended "bottle-around-ship" protocol

Developing confined heterogeneous catalytic systems with diverse and evenly dispersed active sites is a hot research topic for various applications. However, the issues related to the agglomeration of active nanoparticles, spatial distribution uniformity of active nanoparticles, and coverage of active sites with the participation of surfactant or organic ligand restrict the activity or selectivity. In this work, a confined catalyst Pd(PPh3)(4)@MOF808-150 was successfully prepared through a host-guest assembling strategy followed by thermal activation to enhance the rigidity of the catalyst. The synthesized catalyst is employed to generate beta-ketoenamines in the cascade reaction involving nitro-reduction and sequential condensation. This catalyst effectively resolves the electronic preference conflict of the two catalytic steps by isolating the different active sites, demonstrating excellent activity and high chemoselectivity. It is generally applicable to the synthesis of many beta-ketoenamines, with up to 16 kinds of products that have been successfully prepared with conversion and selectivity up to 99%. The extended synthesis method holds significant potential for developing the nanoconfined catalyst without surfactant encapsulation.