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Abstract Ade novoasymmetric strategy for the synthesis ofd‐bradyrhizose diastereomers from an achiral ketoenolester precursor is described. Key transformations used in the stereodivergent approach include two Noyori asymmetric reductions, an Achmatowicz rearrangement, diastereoselective alkene oxidations, and the first example of a palladium(0)‐catalyzed glycosylation of a vinylogous pyranone. The isomeric composition of the bicyclic reducing sugars obtained was analyzed and their behaviour was compared to the natural product, revealing key stereocentres that impact the overall distribution. 

Abstract An asymmetric approach toward the synthesis of the marine natural product aspergillide‐C has been developed. The convergent asymmetric synthesis uses two asymmetric Noyori transfer hydrogenations to enantioselectively prepare the two key fragments, aC‐1 toC‐7 pyranone fragment and aC‐8 toC‐14β‐keto‐sulfone fragment. The absolute stereochemistry of the pyranone fragment was established by a Noyori reduction ofβ‐furylketoester to form a furyl alcohol. An Achmatowicz rearrangement was used to stereoselectively convert the furyl alcohol in to the key pyranone fragment. The absolute stereochemistry of theβ‐keto‐sulfone fragment was established by a Noyori reduction of an ynone to form a propargyl alcohol. An alkyne zipper isomerization was used to stereospecifically convert the propargyl alcohol in to theβ‐keto‐sulfone fragment. Finally, a Pd‐catalyzedC‐glycosylation was used to diastereoselectively couple the two fragments, which when combined with a reduction and Julia‐Kocienski type elimination formed a protected variant of the 4‐epi‐seco‐acid of aspergillide‐C.