Martin Petrzilka

Intramolecular n-alkenylnitrone-additions: Regio- and stereochemistry

Abstract Efficient intramolecular cycloadditions of N-3-alkenyl- and N-4-alkenylnitrones proceed with opposite regioselection which is modified by dipolarophile-substituent effects. Polycyclic isoxazolidines are obtained in a highly stereocontrolled fashion, consistent with an endo-addition of the Z-nitrones.

The regiochemistry of intramolecular n-alkenylnitrone additions: preparative and mechanistic implications

Abstract The opposite regiochemistry, observed for the reactions 7a → 8a and 7d → 8d , as compared with additions 7b → 9b , 7c → 9c and 7e → 9e , supports the hypothesis that in the transition state of nitrone-olefin additions the new C,C bond is more advanced than the C,0, bond. Further examples show the superimposition of substituent effects on this intramolecular control.