Chiral bicyclic keto lactones: determination of the absolute configuration by the study of chiroptical properties and chemical correlation
Author
Summary, in English
Chiral bifunctional oxabicyclodecanediones (keto lactones) were synthesized from the corresponding bicyclo[3.3.1]nonane diones 1-5 by employing a regioselective Baeyer-Villiger oxidation. Enantiomers with high enantiomeric excess were obtained by chiral HPLC enantiomer separation on microcrystalline, triacetylcellulose column. Circular dichroism spectra of molecules containing two chromophores, namely a carbonyl and lactone in one molecule, were studied. The conformational analysis was performed with the aim to apply the octant and lactone sector rules for the determination of the absolute configuration. Ab initio and molecular mechanics calculations revealed that for all compounds investigated a single conformer, that is c-tb for 1a-3a and 1b-2b, and c-tc for 4a, tc-tc for 5a is prevalent in the gas phase at room temperature. The applicability and limitations of the semi-empirical rules was demonstrated. The enantiospecific synthesis of enantiomerically enriched keto lactones 1-2a and 1b-2b from the corresponding enantiomeric ketones unambiguously led to the final proof of the absolute configurations. (C) 2004 Elsevier Ltd. All rights reserved.
Department/s
Publishing year
2004
Language
English
Pages
2405-2413
Publication/Series
Tetrahedron: Asymmetry
Volume
15
Issue
15
Document type
Journal article
Publisher
Elsevier
Topic
- Organic Chemistry
Status
Published
ISBN/ISSN/Other
- ISSN: 0957-4166