Synthesis and stereochemical assignment of (+)-Cladospolide D

Cladospolides A-D are 12-membered, α,β-unsaturated lactones isolated from various species of Cladosporium. Cladospolide D is unique in its γ-keto functionality and possesses antifungal activity; however, the stereochemistry of Cladoapolide D was unknown. We report the asymmetric syntheses to generate both possible diastereomers of Cladospolide D. Two regioselective cross-metatheses were applied to form the carbon skeleton, and the two olefins were differentiated by Michael addition, hydrogenation, and elimination. Later, the macrocycle was achieved through the Yamaguchi protocol. After comparing the spectroscopic data of the synthetic Cladospolide D with the reported values, the stereochemistry of Cladospolide D is confirmed as (2E,5R,11S).

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