55. The regiochemistry of intramolecular n-alkenylnitrone additions: preparative and mechanistic implications
    Oppolzer, W.; Siles, S.; Snowden, R. L.; Bakker, B. H.; Petrzilka, M.
    Tetrahedron Lett. 1979, 20, 4391-4394

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.

DOI : 10.1016/S0040-4039(01)86596-5