Abstract
The n.m.r. spectra of triterpenes related to serratenediol was examined by use of the shift reagent Eu(DPM)3. The upfield and downfield shifts of methyl resonances were observed for the same molecule and this is an example of the importance of the angle dependence term in the McConell and Robertson equation. The relative strength of association at the competing sites in a polyacetoxytriterpene was different, and the association coefficient at each co-ordinating site was taken as a measure of the relative strength of association. Assignment of the methyl resonances of serratenediol diacetate [C(14a)-homo-27-norgammacer-14-ene-3β,21α-diyl diacetate] and serratriol triacetate [C(14a)-homo-27-norgammacer-14-ene-3β,21α,24-triyl triacetate] has been achieved.

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