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.