Highly diastereoselective 5-hexenyl radical cyclizations with Lewis acids and carbohydrate scaffolds.
[figure: see text] Carbohydrates as removable chiral scaffolds for free radical cyclizations were examined for the first time. This investigation illustrates the utility of two inexpensive carbohydrate derivatives as sources of asymmetry for 5-hexenyl radical cyclizations. Diastereomeric ratios as high as 100:1 were achieved with an ester-appended (+)-isosorbide hexose and 70:1 for a diol-protected D-xylose pentose. Temperature dependence, Lewis acids, and solvents were all examined. By correlation with known compounds, the newly generated chiral centers were of the (S)-configuration.
Enholm
E J
EJ
Department of Chemistry, University of Florida, Gainesville, Florida 32611, USA. enholm@chem.ufl.edu
Cottone
J S
JS
Allais
F
F
D000475:Alkenes / Q000737:chemistry*; D002241:Carbohydrates / Q000737:chemistry*; D005609:Free Radicals; D006601:Hexoses / Q000737:chemistry; D007202:Indicators and Reagents; D008968:Molecular Conformation; D015394:Molecular Structure; D010429:Pentoses / Q000737:chemistry; D013237:Stereoisomerism
D000475:Alkenes; D002241:Carbohydrates; D005609:Free Radicals; D006601:Hexoses; D007202:Indicators and Reagents; D010429:Pentoses