Steric and electronic effects on the conformations and singlet oxygen ene regiochemistries of substituted tetramethylethylenes. The origin of the geminal effect

Article abstract of DOI:10.1021/ja00169a030

The reactions of singlet oxygen with 22 allylically substituted tetramethylethylenes have been studied. Steric and electronic effects on the regiochemistries of the ene reactions have been discovered. Large groups and electron-rich groups increase geminal hydrogen abstraction. Molecular mechanics calculations have been conducted and reveal that the site of hydrogen abstraction is correctly predicted by the rotational barriers of the methyl groups.