1H and 13C studies of alkenes,epoxides and cyclic thionocarbonates

¹H and ¹³C chemical shift data are presented and discussed for a number of di- and tri-alkyl substituted alkenes, epoxides and thionocarbonates. The completely stereospecific interconversion of these compounds, together with the n.m.r. data, allows a straightforward and quantitative stereochemical analysis. For ¹H n.m.r., the most useful intermediates proved to be the thionocarbonates. The differential shieldings between cis and trans isomers are tentatively explained in terms of the conformational change of the 5-membered thionocarbonate ring. In ¹³C n.m.r., either series can be useful to distinguish between stereoisomers. The conclusions stemming from the ¹³C n.m.r. results complement the ¹H n.m.r. studies.