Further experimental evidence regarding the occurrence of sudden polarization in acyclic alkenes is presented. It is shown that the yield of formation of the product derived from an intramolecular photochemical [1,3]-OH shift in 1 is dependent only on the polarity of the solvent employed. This result could be well explained in terms of a stabilization of the zwitterionic intermediate formed upon irradiation of 1 by reorientation polarization of the dipole solvent molecules. Besides this, it was found that replacement of the alkyl group at the terminal carbon atom of the C3–C9 exocyclic double bond in 1 by a phenyl substituent led to the occurrence of a photochemical [1,3]-H shift. This directive effect of the substituents at the exocyclic double bond could be well explained on the basis of the sudden polarization model.
Peijnenburg, W. J. G. M., & Buck, H. M. (1988). The effects of substituents and solvent polarity on photochemical [1,3] sigmatropic shifts. Experimental evidence in favor of the occurrence of sudden polarization in acyclic alkenes. Tetrahedron, 44(15), 4927-4940. https://doi.org/10.1016/S0040-4020(01)86197-4