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.