Abstract: | In Z? CH? CH?CH? Y compounds (Z or Y being an alkyl group) the ethylenic part of the spectra is often very complex and the 3J(H? C?C? H) coupling constant which is a good tool for determining the configuration, is not easily determined. We have studied such allylic derivatives and many configurations have been assigned through stereospecific synthesis. Except a very few cases, δ CH(Z) of the cis isomer is larger than δ CHZ of the trans isomer. In alcohols RCH?CH? CHOHR′ the stereoisomers behave differently in solutions with europium, praseodymium, holmium and dysprosium complexes. The spectra of the trans isomers remain strongly coupled but 3J(H? C?C? H) becomes easy to measure in the cis compounds. |