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
Mechanistic Insights into the Formation of δ‐Lactones by Cerium‐Catalyzed Aerobic Coupling of β‐Oxoesters with Enol Acetates
作者:Jean‐Marico Speldrich、Jens Christoffers
DOI:10.1002/ejoc.202001532
日期:2021.2.12
The mechanism of the cerium‐catalyzed radical coupling reaction of β‐oxoesters, enol acetates, and dioxygen was elucidated by the introduction of cyclopropyl substituents and stereocenters in the starting materials. The 1,2‐alkyl shift within the endoperoxidic oxycarbenium intermediate proceeded with retention of configuration.
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
A Simple and Effective Method for α-Hydroxylation of β-Dicarbonyl Compounds Using Oxone as an Oxidant without a Catalyst
作者:Jun Yu、Jian Cui、Chi Zhang
DOI:10.1002/ejoc.201000940
日期:2010.12
Oxone has been found to be a highly efficient reagent for the introduction of a hydroxy group at the α position of a variety of β-dicarbonylcompounds in the homogeneous solvent mixture of water and 1,4-dioxane at 60 °C.
已发现 Oxone 是一种高效试剂,可在 60 °C 下在水和 1,4-二恶烷的均相溶剂混合物中在各种 β-二羰基化合物的 α 位引入羟基。
A Biomimetic Iron Catalyst for the Epoxidation of Olefins with Molecular Oxygen at Room Temperature
作者:Kristin Schröder、Benoît Join、Arlin Jose Amali、Kathrin Junge、Xavi Ribas、Miquel Costas、Matthias Beller
DOI:10.1002/anie.201004623
日期:2011.2.7
It's no sacrifice: A bio‐inspired iron system, in which a β‐keto ester serves as a sacrificial cosubstrate, readily epoxidizes olefins under ambient conditions with air. Aromatic olefins are oxidized in high yields with excellent chemoselectivity. Mechanistic investigations point out substantial differences to well‐known radical‐based autoxidations.