Comparison of the room- and low-temperature
1H NMR spectra of the bis-(
R)- or bis-(
S)-MPA esterderivative of an open chain
sec,sec-1,2-diol allows the easy determination of its relative stereochemistryand in some cases absolute configuration. If the diol is anti, its absolute configuration can be directlydeduced from the signs of
T1T2 for substituents R
1/R
2, but if the relative stereochemistry of the diol issyn, the assignment of its absolute configuration requires the preparation of two derivatives (both thebis-(
R)- and bis-(
S)-MPA esters), comparison of their room-temperature
1H NMR spectra, and calculationof the
RS signs for the methines H
(R
1) and H
(R
2) and R
1/R
2 protons. The reliability of thesecorrelations is validated with 17 diols of known absolute configuration used as model compounds.