Chemoenzymatic Asymmetric Total Synthesis of Nonanolide (Z)‐Cytospolides D, E and Their Stereoisomers

Abstract

AbstractChemoenzymatic asymmetric total synthesis of the (Z)‐isomer of the naturally occurring decanolide cytospolides D, E and six stereoisomers is reported. The main highlight of the synthetic venture involves ring‐closing metathesis (RCM) reaction of a suitably functionalized ester compound, which was assembled by the Yamaguchi coupling of the required acid and alcohol fragments. The alcohol fragment was accessed by two alternative chemoenzymatic processes, one being hydroxynitrile lyase mediated hydrocyanation, whereas lipase‐catalyzed transesterification was the key sep in the second route. The acid fragment was constructed by an enantioselective enzymatic desymmetrization (EED) of prochiral 2‐methyl‐1,3‐propanediol and Corey–Bakshi–Shibata (CBS) mediated stereoselective carbonyl reduction.