Synthesis of 6-hydroxy δ-lactones and 5,6-dihydroxy eicosanoic/docosanoic acids from meadowfoam fatty acids via a lipase-mediated self-epoxidation

Meadowfoam fatty acids were reacted with hydrogen peroxide in a lipase-catalyzed autocatalytic system, forming a mixture of 5,6-epoxyeicosanoic, 13,14-epoxydocosanoic, 5,6-epoxydocosanoic, and 5,6-13,14-diepoxydocosanoic acids in 98% yield. The 5,6-epoxy acids were cyclized to 6-hydroxy δ-eicosanoic/docosanoic lactones by sulfuric acid catalysis in high yield (99%). 5,6-Dihydroxy acids could be obtained from 6-hydroxy δ-lactones by a simple alkaline work-up procedure. Meadowfoam fatty acids were converted (77% yield) in a one-pot reaction to 6-hydroxy δ-lactones by in situ performic acid epoxidation and subsequent addition of sulfuric acid.