| Abstract: | The proton NMR spectra of 2,3,4,4-tetramethyl-3-t-butylpent-1-ene rotarners have been completely assigned by low temperature NOE measurements. Chemical shifts and cis and trans allylic coupling constants are unambiguously determined. It is shown that other 2-substituted propenes can be assigned on the basis of the coupling constants, but not from the chemical shift data. In 1,2-disubstituited propenes, however, the transoid coupling constant falls in the range of the cisoid coupling constant values of the 2-substituted propenes. Coupling constants cannot, therefore, be used in the 1,2-disubstituted propene series as a criterion for determining structure. |
