Stereochemical issues on the fragmentation of non-enolisable β-heterosubstituted-cyclopentanones with wet and anhydrous potassium hydroxide
摘要:
Tandem Haller-Bauer-scission/Grob-fragmentation reaction of cyclopentanone bearing a leaving group in beta-position involves antiperiplanar arrangements which can be also achieved from epimeric derivatives, probably due to the high flexibility of the five-membered ring. We have observed that epimeric compounds react at different rates if the leaving group is a halogen and leads to very different types of compounds when it is a mesyl group. (C) 2010 Elsevier Ltd. All rights reserved.
in a nonconcerted fashion, from the bicyclicmethylenecyclopropanes 26, 30, 33, and 40, through the planar diradicals 28, 31, 35, and 50, respectively. The different reaction modes are viewed as being caused by the different coupling probabilities of the underlying vibrations. The orthogonal or planar geometries of the diradicals were derived from stereochemical and kinetic arguments. Additional thermodynamic
Es wird ein Verfahren zur Herstellung von 2,2,4-Trimethyl-cyclopent-4-en-1,3-dion beschrieben, bei welchem 3,5,5-Trimethyl-cyclohex-2-en-1,4-dion mit Sauerstoff oder einem Sauerstoff enthaltenden Gas in Gegenwart eines Katalysators auf der Basis von Mangan, Kobalt oder Kupfer oxidiert wird.