Relative and Absolute Stereochemistry of Secondary/Secondary Diols: Low-Temperature 1H NMR of Their bis-MPA Esters§

摘要: Comparison of the room- and low-temperature 1H NMR spectra bis-(R)- or bis-(S)-MPA ester derivative an open chain sec,sec-1,2-diol allows easy determination its relative stereochemistry in some cases absolute configuration. If diol is anti, configuration can be directly deduced from signs DeltadeltaT1T2 for substituents R1/R2, but if syn, assignment requires preparation two derivatives (both esters), comparison their room-temperature spectra, calculation DeltadeltaRS methines Halpha(R1) Halpha(R2) R1/R2 protons. The reliability these correlations validated with 17 diols known used as model compounds.