文摘
Making distinctions between two stereoisomers characterized by diastereotopic deuterium atoms can ordinarily be achieved using standard NMR spectroscopic methods. Mixtures of stereoisomers having both diastereotopic and enantiotopic deuterium labels, however, may be difficult to analyze quantitatively. The present work introduces a simple way to gain quantitative analyses of mixtures of the four stereoisomeric 2-deuterio-1-vinylcyclobutanes, an essential prerequisite to establishing the stereochemical characteristics of the thermal stereomutations of vinylcyclobutane and its structural isomerizations to cyclohexene. The unconventional NMR method introduced and validated in this work will likely prove convenient and generally applicable to related stereochemical investigations.