Porous and Robust Lanthanide Metal-Organoboron Frameworks as Water Tolerant Lewis Acid Catalysts

Porous and robust 12-connected metal-organic frameworks (MOFs) were constructed by linking tetranuclear lanthanide (Ln) carbonate clusters with organoboron-derived tricarboxylate bridging ligands. The high-connectivity Ln-MOFs feature remarkable thermal and hydrolytic stability and a large number of isolated Lewis acid B(III) and Ln(III) sites on the pore surfaces. The Nd-MOF assisted with sodium dodecylsulfate was found to be highly effective, recyclable, and reusable heterogeneous catalyst for the carbonyl allylation reaction, the Diels-Alder reaction, and the Strecker-type reaction in water. The transformations were cocatalyzed by Nd(III) and B(III) Lewis acids, with activities much higher than those of the individual organoboron and lanthanide counterparts and their mixture. This work highlights the potential of generating highly efficient water-tolerant solid catalysts via heterogenization of different weak and/or mild Lewis acids in confined spaces of robust MOFs.