Lactones 12.: Enzymatic lactonization of γ,δ-epoxy esters by the apple fruit and Jerusalem artichoke bulb

The enzymatic lactonization of three acyclic γ,δ-epoxy esters (ethyl 3,7-dimethyl-4,5-epoxyoctanoate, ethyl 3,7,7-trimethyl-4,5-epoxyoctanoate, and ethyl 3,3,7-trimethyl-4,5-epoxyoctanoate) by apple fruit (Malus silvestris) and Jerusalem artichoke bulb (Helianthus tuberosus L.) was investigated. The substrates were transformed into a mixture of isomeric δ-hydroxy-γ-lactones and γ-hydroxy-δ-lactones. The γ-lactones (yields ranging from 45–70%) predominated over δ-lactones (yields ranging from 8–40%). The composition of the product mixture depended on the structure of substrate as well as the biocatalyst. The enzymatic system in these biocatalysts also exhibited diastereoselectivity and enantioselectivity.