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Redox-Noninnocent Ligand-Supported Vanadium Catalysts for the Chemoselective Reduction of CX (X = O, N) Functionalities
journal contribution
posted on 2019-09-12, 15:35 authored by Guoqi Zhang, Jing Wu, Shengping Zheng, Michelle C. Neary, Jincheng Mao, Marco Flores, Ryan J. Trovitch, Pavel A. DubCatalysis
is the second largest application for V after its use
as an additive to improve steel production. Molecular complexes of
vanadium(V) are particularly useful and efficient catalysts for oxidation
processes; however, their ability to catalyze reductive transformations
has yet to be fully explored. Here we report the first examples of
polar organic functionality reduction mediated by V. Open-shell VIII complexes that feature a π-radical monoanionic 2,2′:6′,2″-terpyridine
ligand (Rtpy•)− functionalized
at the 4′-position (R = (CH3)3SiCH2, C6H5) catalyze mild and chemoselective
hydroboration and hydrosilylation of functionalized ketones, aldehydes,
imines, esters, and carboxamides with turnover numbers (TONs) of up
to ∼1000 and turnover frequencies (TOFs) of up to ∼500
h–1. Computational evaluation of the precatalyst
synthesis and activation has revealed underappreciated complexity
associated with the redox-active tpy chelate.
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Keywords
Open-shell V III complexesestersfunctionality reductionC 6 H 5oxidation processesRtpyligandfunctionalized ketonesprecatalyst synthesisredox-active tpy chelateComputational evaluationMolecular complexesFunctionalities Catalysisactivationability3 SiCH 2carboxamidesteel productionchemoselective hydroborationcatalyze reductive transformationsCH 3additiveiminemonoanionicπ-frequencyChemoselective ReductionRedox-Noninnocent Ligand-Supported Vanadium CatalystsTOFhydrosilylationapplicationaldehydeturnover numbersterpyridineturnover frequenciesvanadiumcomplexity