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
Remarkable rate acceleration of the solvent-free Baeyer–Villiger reaction on the surface of NaHCO3 crystals for sterically congested cyclic and acyclic ketones
Baeyer-Villiger reactions of sterically crowded cyclic and acyclic ketones are remarkably accelerated by carrying out the reactions under solvent-free conditions in the presence of powdered NaHCO3. The corresponding lactones and esters have been obtained in excellent yields. (C) 2002 Elsevier Science Ltd. All rights reserved.