Formation of δ-Lactones with <i>anti</i>
-Baeyer-Villiger Regiochemistry: Investigations into the Mechanism of the Cerium-Catalyzed Aerobic Coupling of β-Oxoesters with Enol Acetates
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 this case of an oxidative C-C coupling reaction the less substituted alkyl residue undergoes a 1,2-shift. An endoperoxidic oxycarbenium ion comparable to the Criegee intermediate
Synthesis of 1,4-Diketones from β-Oxo Esters and Enol Acetates by Cerium-Catalyzed Oxidative Umpolung Reaction
作者:Irina Geibel、Jens Christoffers
DOI:10.1002/ejoc.201600057
日期:2016.2
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
1,4-Diketones were prepared by cerium-catalyzedoxidative coupling of styrene with molecular oxygen and 1,3-dicarbonyl compounds. This two-step sequence was performed as a one-pot procedure without isolation of the intermediate products. The first step is a metal-catalyzed radical reaction yielding 3-hydroxy-1,2-dioxane derivatives being the cyclotautomers of initially formed 4-hydroperoxy ketones
Eight-membered-ringlactams were prepared by the Bi-catalyzed reaction of 1,4-diketones with primaryamines. These lactams define a new type of non-planar molecular scaffold with three points allowing for diversification, which were evaluated as the basis for combinatorial library synthesis. For this reason, reaction conditions were optimized, and the scope and limitations were investigated. After
Dihydropyridazine Derivatives with Cyclopenta-, Benzo-, Furo-, Thiopyrano- and Pyrido-Annulation
作者:Miriam Penning、Jens Christoffers
DOI:10.1002/ejoc.201201158
日期:2013.1
Regioisomeric [c]annulated pyridazines were prepared from arylhydrazines and carbocyclic or heterocyclic β-oxo esters with an α-phenacetyl moiety. With AcOH/EtOH, the hydrazones were preferentially formed at the endocyclic ketone, which are further cyclized with trifluoroacetic acid (TFA)/CH2Cl2 to give 2,4a-dihydropyridazines. Use of TFA/CH2Cl2 led hydrazones at the exocyclic benzoyl group, which