Related Experiment Video
Updated: Sep 20, 2025
Line Shape Analysis of Dynamic NMR Spectra for Characterizing Coordination Sphere Rearrangements at a Chiral Rhenium Polyhydride Complex
Published on: July 27, 2022
Expanding Zirconocene Hydride Catalysis: In Situ Generation and Turnover of ZrH Catalysts Enabling Catalytic Carbonyl
Rebecca A Kehner1, Matthew Christian Hewitt1, Liela Bayeh-Romero1
1Department of Chemistry and Biochemistry, Baylor University, Waco, Texas 76706, United States.
Abstract:
Despite the wide use and popularity of metal hydride catalysis, methods utilizing zirconium hydride catalysts remain underexplored. Here, we report the development of a mild method for the in situ preparation and use of zirconium hydride catalysts. This robust method requires only 2.5-5 mol % of zirconocene dichloride in combination with a hydrosilane as the stoichiometric reductant and does not require careful air- or moisture-free techniques. A key finding of this study concerns an amine-mediated ligand exchange en route to the active zirconocene hydride catalyst. A mechanistic investigation supports the intermediacy of an oxo-bridged dimer precatalyst. The application of this method to the reduction of a wide variety of carbonyl-containing substrates, including ketones, aldehydes, enones, ynones, and lactones, is demonstrated with up to 92% yield and exhibits broad functional group tolerability. These findings open up alternative avenues for the catalytic application of chlorozirconocenes, potentially serving as the foundation for broader applications of zirconium hydride catalysis.
Related Concept Videos
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
02:23Alcohols from Carbonyl Compounds: Reduction
Catalytic hydrogenation is similar to the reduction of an alkene or alkyne by adding H2 across the pi bond in the presence of transition metal catalysts like Raney Ni, Pd–C, Pt, or Ru. Aldehydes and ketones can be reduced by this method, often under mild to moderate heat (25–100°C) and...
02:13Reduction of Alkenes: Catalytic Hydrogenation
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the...
01:28Reduction of Benzene to Cyclohexane: Catalytic Hydrogenation
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.