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Updated: May 19, 2026
Palladium N-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions
Published on: July 30, 2017
Rhodacarborane complexes with a triphenylphosphonium substituent as efficient catalysts for on-water transfer
Mikhail M Vinogradov1, Yulia V Nelyubina2, Ivan A Godovikov1
1A.N. Nesmeyanov Institute of Organoelement Compounds of Russian Academy of Sciences, INEOS, Vavilova str. 28, Moscow 119334, Russia. vmm@ineos.ac.ru.
Abstract:
Two isomeric rhodacarborane chloride complexes [1,8-Bn2-2,2-Cl2-X-PPh3-2,1,8-closo-RhC2B9H8]2 (X = 7 and 11) were synthesized. One of them (X = 7) exhibits high catalytic activity in the on-water reduction of aromatic and aliphatic aldehydes and ketones with ammonium formate to the corresponding alcohols with a 0.2 mol% loading. The enantiopure form of a planar chiral catalyst was obtained via isolation of a cyclometallated complex with (S)-proline. The enantiopure form of the catalyst affords alcohols with enantiomeric excess when prochiral ketones are used in the reaction. The same catalyst is active in the Oppenauer-type oxidation of (±)-1-phenylethanol with acetone in the presence of K2CO3. The transfer hydrogenation is accompanied by in situ reversible cyclometallation of the catalytic species engaging the ortho-CH bonds of PPh3.
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