Stereochemistry of the methyne-methylene conversion in the biogeneration of (S)-δ-decanolide and (S)-γ-dodecanolide from (13RS)-13- hydroxyoctadeca-9Z,11E-dienoic and (10RS)-10-hydroxyoctadec-8E-enoic acid

In Cladosporium suaveolens the bioconversion of (13RS)-13-hydroxy-[9,10,11, 12-²H₄]octadeca-9Z,11E-dienoic acid into axially, 2,3,4-trideuteriated (S)-δ-decanolide indicates that protonation of the dienic system occurring at some stage of the degradative sequence takes place on the same face of the molecule. The protonation at position 9 of (10RS)-10-hydroxy-[9,10-²H₂]octadeca-8E-enoic acid occurring in Yarrowia lipolytica during the biogeneration of (S)-γ-dodecanolide shows the same steric course.