- Formation of δ-Lactones with anti-Baeyer–Villiger Regiochemistry: Investigations into the Mechanism of the Cerium-Catalyzed Aerobic Coupling of β-Oxoesters with Enol Acetates
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The cerium-catalyzed, aerobic coupling of β-oxoesters with enol acetates and dioxygen yields δ-lactones with a 1,4-diketone moiety. In contrast to the Baeyer–Villiger oxidation (BVO), where the higher substituted residue migrates; in the case of this oxid
- Geibel, Irina,Dierks, Anna,Müller, Thomas,Christoffers, Jens
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p. 7245 - 7254
(2017/05/31)
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- Formation of δ-Lactones by Cerium-Catalyzed, Baeyer-Villiger-Type Coupling of β-Oxoesters, Enol Acetates, and Dioxygen
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Formation of δ-lactones is observed when cyclopentanone-2-carboxylates are converted in a cerium-catalyzed reaction with α-aryl vinyl acetates under oxidative conditions. The products of this transformation possess a 1,4-dicarbonyl constitution together with a quaternary carbon center. Atmospheric oxygen is the oxidant in this process, which can be regarded as ideal from economic and ecological points of view. Further advantages of this new C-C coupling and oxidation reaction are its operational simplicity and the application of nontoxic and inexpensive CeCl3·7 H2O as precatalyst. This so far unprecedented reaction is proposed to proceed via 1,2-dioxane derivatives, which decompose under formation of an oxycarbenium cation in a Baeyer-Villiger-type pathway. This mechanistic picture is supported by the observation that electron-rich (donor substituted or heteroaromatic) enol esters give higher yields than electron deficient congeners. Apart from 1,4-diketones and α-hydroxylated β-oxoesters formed as byproducts, the yields of δ-lactones range from moderate to good (up to 74%).
- Geibel, Irina,Dierks, Anna,Schmidtmann, Marc,Christoffers, Jens
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p. 7790 - 7798
(2016/09/09)
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- Synthesis of 1,4-Diketones from β-Oxo Esters and Enol Acetates by Cerium-Catalyzed Oxidative Umpolung Reaction
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Cyclic β-oxo esters are converted with enol acetates in a cerium-catalyzed, oxidative Umpolung reaction to furnish 1,4-diketones with up to 95 % yield. Atmospheric oxygen is the oxidant in this process, which can be regarded as ideal from economic and ecological points of view. Further advantages of this new C-C coupling reaction are its operational simplicity and the application of nontoxic and inexpensive CeCl3·7H2O as precatalyst.
- Geibel, Irina,Christoffers, Jens
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p. 918 - 920
(2016/03/01)
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- Cerium-Catalyzed Reaction of β-Dicarbonyl Compounds with Styrene and Atmospheric Oxygen
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The cerium-catalyzed C-C coupling reaction of carbo- and heterocyclic β-dicarbonyl compounds 1 with styrenes 4, using oxygen (air) as the oxidant, at ambient temperature, is reported. The reaction afforded a mixture of diastereoisomeric hydroperoxides 5 w
- Christoffers, Jens,Werner, Thomas,Frey, Wolfgang,Baro, Angelika
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p. 4879 - 4886
(2007/10/03)
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