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.