STEREOSELECTIVITY IN THE CYCLOADDITION OF CHIRAL GLYCERALDEHYDE DERIVED NITRONE TO STYRENE

The stereoselectivity of 1,3-dipolar cycloadditions of C-alpha-alkoxy- substituted chiral nitrones with styrene was investigated. Diastereose lectivity far the glyceraldehyde derived nitrone cycloaddition to the styrene was found w(r) 73:11:9:7. The major product was found to have the C-3/C-4' erythro and C-3/C-5cis relative stereochemistry. It likel y derives via less hindered Endo attack and in an antiperiplanar manne r with respect to the largest methylene group of the dioxolane ring. T he cycloaddition with L-lactate derived nitrone was less selective and stereoisomers were found in the ratio of w(r) = 39:30:20:11.