RSS-Feed abonnieren
DOI: 10.1055/s-1999-3686
Sigmatropic Rearrangement of Uronic Acid Derived Saccharide Allyl Ketene Acetals. A Study of Stereochemistry and Structural Limitations
Publikationsverlauf
Publikationsdatum:
31. Dezember 1999 (online)
![](https://www.thieme-connect.de/media/synthesis/199901/lookinside/thumbnails/10.1055-s-1999-3686-1.jpg)
Allyl ketene acetal Claisen rearrangement of urinoc acid derivatives with furanoside structure was studied. Reproducibility of the observed stereodiscrimination was confirmed in the conversion of enantiomeric starting materials. From X-ray structural data of the major reaction product obtained from a cis-pentenyl uronate, the transition state was proven to preferentially adopt a chair-like geometry. Alterations in the protecting group pattern led to a significant decrease in total yields. Use of β-deoxygenated starting material allowed a greater extent of variation, but was accompanied by the total loss of stereodiscrimination. For the first time, the reaction was applied to pyranoid starting material structures. The conversion of a gluco-configurated compound remaining unsuccessful, with the corresponding galacto and 4-deoxy derivatives an interesting stereoselectivity could be observed. This was lost by further structural simplification to a 1,4-dideoxypyranoid ring. This way, however, a substantial improvement in yield could be achieved.
Claisen rearrangements - allyl ketene acetals - furanosiduronates - pyranosiduronates