The Brønsted basicity in activated metal-organic framework-808 (hereinafter denoted as MOF-808a) was confirmed by the analyses of CO-TPD-MS, in situ DRIFTS, and acid-base titration. MOF-808a exhibited efficient recyclable catalytic activities for Heck coupling and oxidation of alcohol as a one-pot tandem reaction in base-free catalysis. It is the first evidence of the Brønsted basicity in zirconium metal-organic frameworks (Zr-MOFs) and gave rise to a new opportunity to extend the catalytic application of Zr-MOFs.
The convenient cross‐coupling of sp2 or sp3 carbons with a specific boron vertex on carborane cage represents significant synthetic values and insurmountable challenges. In this work, we report an Rh‐catalyzed reaction between o‐carborane and N‐acyl‐glutarimides to construct various Bcage−C bonds. Under the optimized condition, the removable imine directing group (DG) leads to B(3)− or B(3,6)−C couplings, while the pyridyl DG leads to B(3,5)−Ar coupling. In particular, an unexpected rearrangement of amide reagent is observed in pyridyl directed B(4)−C(sp3) formation. This scalable protocol has many advantages, including easy access, the use of cheap and widely available coupling agents, no requirement of an external ligand, base or oxidant, high efficiency, and a broad substrate scope. Leveraging the RhI dimer and twisted amides, this method enables straightforward access to diversely substituted and therapeutically important carborane derivatives at boron site, and provides a highly valuable vista for carborane‐based drug screening.
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