Phenazine Radical Cations as Efficient Homogeneous and Heterogeneous Catalysts for the Cross‐Dehydrogenative Aza‐Henry Reaction

The redox activity of molecular phenazine catalysts has been previously exploited for aerobic oxidative amine homo‐ and cross‐coupling reactions. In this contribution, we have extended the reaction scope of this novel type of organocatalyst and used them in the cross‐dehydrogenative aza‐Henry coupli...

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Bibliographic Details
Published in:Helvetica chimica acta 2020-12, Vol.103 (12), p.n/a
Main Authors: Unglaube, Felix, Hünemörder, Paul, Guo, Xuewen, Chen, Zixu, Wang, Dengxu, Mejía, Esteban
Format: Article
Language:English
Subjects:
Aerobic conditions
aerobic oxidation
aza-Henry reaction
Catalysts
Cations
Chemical reactions
Coupling (molecular)
Cross coupling
cross-dehydrogenative coupling
Dehydrogenation
Nitromethane
Phenazine
phenazines
Polymers
porous organic polymers
Reaction mechanisms
Selectivity
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Summary:The redox activity of molecular phenazine catalysts has been previously exploited for aerobic oxidative amine homo‐ and cross‐coupling reactions. In this contribution, we have extended the reaction scope of this novel type of organocatalyst and used them in the cross‐dehydrogenative aza‐Henry coupling of isoquinolines with nitromethane under aerobic conditions. Additionally, we have designed and prepared a novel porous organic polymer by cross‐linking of tetrakis(4‐bromophenyl)silane and dihydrophenazine through Pd‐catalyzed Buchwald‐Hartwig cross‐coupling. This new type of heterogeneous catalyst, apart from being robust and easily reusable, also showed outstanding catalytic activities and improved selectivity compared to its molecular counterpart. A plausible reaction mechanism was proposed based on spectroscopic and kinetic measurements.
ISSN:0018-019X
1522-2675
DOI:10.1002/hlca.202000184