Cobalt-bridged secondary building units in a titanium metal-organic framework catalyze cascade reduction of N-heteroarenes

We report here a novel Ti 3 -BPDC metal-organic framework (MOF) constructed from biphenyl-4,4′-dicarboxylate (BPDC) linkers and Ti 3 (OH) 2 secondary building units (SBUs) with permanent porosity and large 1D channels. Ti-OH groups from neighboring SBUs point toward each other with an O-O distance of 2 Å, and upon deprotonation, act as the first bidentate SBU-based ligands to support Co II -hydride species for effective cascade reduction of N-heteroarenes (such as pyridines and quinolines) via sequential dearomative hydroboration and hydrogenation, affording piperidine and 1,2,3,4-tetrahydroquinoline derivatives with excellent activity (turnover number ∼ 1980) and chemoselectivity. We report here the synthesis of a robust Ti-MOF with novel SBUs and its use as oxo ligands to chelate Co-hydrides for cascade reduction of N -heteroarenes.