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On the basis of the assignment of methylene proton signals in 1H NMR and determination of the chemical shift difference (Δδ), the relative configuration of 1,3,n-methyl-branched deoxypropionates can be determined directly. Comparison of the chemical shifts in the corresponding syn- and anti-configured compound pairs shows remarkable differences, while the absolute values depend on the presence and nature of adjacent functional groups. The determination of the Δδ values provides a reliable assessment of the relative configuration in 1,3,n-methyl-branched polypropionate chains and is even valid for macrocycles. [ABSTRACT FROM AUTHOR]

The first asymmetric total synthesis of vittatalactone features the divergent synthesis of two diastereomers to assign the absolute configuration of the natural product. Its consecutive propionate and deoxypropionate stereogenic centers are established by enantioselective o-DPPB directed allylic substitution. [ABSTRACT FROM AUTHOR]