Iridium-catalyzed alkane C−H borylation has long suffered from poor atom economy, resulting from both the inclusion of only 1 equiv of boron from the diboron reagent and a requirement for neat substrate. An appropriately substituted dipyridylarylmethane ligand was found to give highly active alkane borylation catalysts that facilitate C−H borylation with improved efficiency. This system provides for complete consumption of the diboron reagent, producing 2 molar equivalents of product at low catalyst loadings. The superior efficacy of this system also enables borylation of unactivated alkanes in hydrocarbon solvent with a reduced excess of substrate and improved functional group compatibility. The effectiveness of this ligand is displayed across a selection of functional groups, both under traditional borylation conditions in neat substrate and under atypical conditions in cyclohexane solvent. The utility of this catalytic system is exemplified by the borylation of substrates containing polar functionality, which are unreactive toward C−H borylation under neat conditions.

Cationic bis(phosphine)iridium complexes are found to catalyze the cleavage of cyclohexyl methyl ethers by triethylsilane. Selectivity for C−O cleavage is determined by the relative rates of S N 2 demethylation versus S N 1 demethoxylation, with the axial or equatorial disposition of the silyloxonium ion intermediate acting as an important contributing factor. Modulation of the electron-donor power of the supporting phosphine ligands enables a switch in selectivity from demethylation of equatorial methyl ethers to 2°demethoxylation. Applications of these accessible catalysts to the selective demethoxylation of the 3α-methoxy group of cholic acid derivatives is demonstrated, including a switch in observed selectivity controlled by 7α-substitution. The resting state of the catalyst has been characterized for two phosphine derivatives, demonstrating that the observed switch in C−O cleavage selectivity likely results from electronic factors rather than from a major perturbation of the catalyst structure.

Highly defective UiO-66-type MOFs are stabilized by Lewis basic sites on pendant groups, resulting in water-, acid-, and base-stable MOFs.

A catalytic, light-promoted hydrosilylative cleavage reaction of alkyl ethers is reported. Initial studies are consistent with a mechanism involving heterolytic silane activation followed by delivery of a photohydride equivalent to a silyloxonium ion generated in situ. The catalyst resting state is a mixture of Cp*Ir­(ppy)­H (ppy = 2-phenylpyridine-κC,N) and a related hydride-bridged dimer. Trends in selectivity in substrate reduction are consistent with nonradical mechanisms for C–O bond scission. Irradiation of Cp*Ir­(ppy)H with blue light is found to increase the rate of hydride delivery to an oxonium ion in a stoichiometric test. A comparable rate enhancement is found in carbonyl hydrosilylation catalysis, which operates through a related mechanism also involving Cp*Ir­(ppy)H as the resting state.