Analyse Conformationnelle en Serie Alcoylidene-5 Dioxanne-1,3

Some 5-alkylidene 2-alkyl 1,3-dioxans have been studied by NMR. Analysis of the spectra leads to the conclusion that these derivatives are predominantly in the chair form, the alkyl substituent on carbon 2 being in the equatorial position. In the case of 5-alkylidene 1,3 dioxans unsubstituted at carbon 2, there is a rapid ring inversion with a very low energy barrier.