Über die 1,2‐Verschiebung von Carbonestergruppen bei der Benzilsäureumlagerung von α,β‐Dioxobuttersäure‐estern. 25. Mitteilung über Reduktone und Tricarbonylverbindungen [1]

Abstract

Summary. I n the benzilic acid type rearrangement of t-butyl a, ,&dioxobutyrate (VII) the intact t-butoxycarbonyl group is shifted t o the p-carbonyl carbon atom.

Tandem Oxidation/Rearrangement of β-Ketoesters to Tartronic Esters with Molecular Oxygen Catalyzed by Calcium Iodide under Visible Light Irradiation with Fluorescent Lamp

“…The mixture of α,β-diketoester and its hydrated species 3a , which we could obtain as an intermediate, increased for 2 h and gradually decreased with increasing yield of 2aa (Table , entry 9) . In addition, 2aa was obtained in 90% yield when 3a was used as a substrate under the conditions mentioned above …”

An MNDO SCF-MO study of the mechanism of the benzilic acid and related rearrangements

“…16 Whilst clearly an approximation, such a procedure should give a qualitative indication of the characteristics of such species and the expected substituent effects. The UHF procedure however cannot be used to model quantitatively the conversion of biradicals such as (5) to (3), since a conversion from the triplet into singlet manifolds occurs. Pathway (c) (Scheme) involves intramolecular proton transfer in (5) resulting in the formation of a singlet biradical (6), followed by migration to form (4).…”

“…The UHF procedure however cannot be used to model quantitatively the conversion of biradicals such as (5) to (3), since a conversion from the triplet into singlet manifolds occurs. Pathway (c) (Scheme) involves intramolecular proton transfer in (5) resulting in the formation of a singlet biradical (6), followed by migration to form (4). Such a process can be studied within the UHF formalism, since it occurs entirely on the singlet manifold.…”