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
Modular POP Ligands in Rhodium-Mediated Asymmetric Hydrogenation: A Comparative Catalysis Study
作者:José L. Núñez-Rico、Pablo Etayo、Héctor Fernández-Pérez、Anton Vidal-Ferran
DOI:10.1002/adsc.201200477
日期:2012.11.12
Highly efficient and enantioselectivehydrogenation reactions for α-(acylamino)acrylates, itaconic acid derivatives and analogues, α-substituted enolester derivatives, and α-arylenamides (25 substrates) catalyzed by chiral cationic rhodium complexes of a set of POP ligands have been developed. The catalytic systems derived from these POP ligands provided a straightforward access to enantiomerically
Rhenium complex-catalyzed coupling reaction of enol acetates with alcohols
作者:Rui Umeda、Yuuki Takahashi、Yutaka Nishiyama
DOI:10.1016/j.tetlet.2014.09.054
日期:2014.10
The reaction of enolacetates with alcohols in the presence of a catalytic amount of a rhenium complex, such as ReBr(CO)5, produced the corresponding ketones and aldehydes in moderate to good yields. It was suggested that the preparation of an ether, an intermolecular dehydrated product, was the first step of the reaction.
When benzylic and allylic alcohols were treated with enolacetate in the presence of a catalytic amount of a rhenium complex, ReBr(CO)5, the carbon-carbon bond formation of the alcohols and enolacetate smoothly proceeded to give the corresponding ketones and aldehyde in moderate to good yields. For the reaction of allylic alcohols, γ,δ-unsaturated carbonylcompounds were obtained in good yields. When