Trivalent Zirconium and Hafnium Metal-Organic Frameworks for Catalytic 1,4-Dearomative Additions of Pyridines and Quinolines

Abstract

We report the quantitative conversion of [M^IV₆(μ₃-O)₄(μ₃-OH)₄Cl₁₂]^6- nodes in the MCl₂-BTC metal-organic framework into the [M^III₆(μ₃-O)₄(μ₃-ONa)₄H₆]^6- nodes in M^IIIH-BTC (M = Zr, Hf; BTC is 1,3,5-benzenetricarboxylate) via bimetallic reductive elimination of H₂ from putative [M^IV₆(μ₃-O)₄(μ₃-OH)₄H₁₂]^6- nodes. The coordinatively unsaturated M^IIIH centers in M^IIIH-BTC are highly active and selective for 1,4-dearomative hydroboration and hydrosilylation of pyridines and quinolines. This work demonstrated the potential of secondary building unit transformation in generating electronically unique and homogeneously inaccessible single-site solid catalysts for organic synthesis.