beta.-Epimerization and .gamma.-hydrogen abstraction via homoenolate ions

Using α- and β-Epimerizations of cis-2,3-Bis(hydroxymethyl)-γ-butyrolactone for the Synthesis of Both Enantiomers of Enterolactone

In the context of asymmetric synthesis, epimerization is usually problematic. Here, we describe the use of the epimerization of cis-2,3-bis(hydroxymethyl)-γ-butyrolactone for the synthesis of enterolactones with anti-carcinogenic, anti-inflammatory, anti-angiogenic, and antioxidant activity. Selective α- or β-epimerization of a γ-butyrolactone was used to selectively synthesize both enantiomers of enterolactone. Theoretical and kinetic studies were performed to elucidate the epimerization mechanism.

Biosynthesis in theory and practice: structure determinations

Classical appraoches to structure determinations of natural molecules can be assisted by biosynthetic considerations. Application of these needs some structural evidence, based on degradations and spectra, as to biogenetic type. This evidence can be effectively supplemented by incorporations of precursors labelled with 14C, 13C or 15N, as appropriate, with examinations of the distributions of label in the product. Several examples of both classical and incorporation techniques are reviewed.

Isomerization of 4-amino-6,7-diphenylbicyclo[2.2.2]octan-2-ones

Under strongly basic conditions (6SR,7SR)-4-amino-6,7-diphenylbicyclo[2.2.2]octan-2-ones isomerized regioselectively in position 6 giving their (6RS,7SR) analogues. The structure of the new products was established with the aid of NMR experiments.Key words: aminobicyclo[2.2.2]octanones, isomerization, structure elucidation.