De Novo Asymmetric Synthesis of Daumone via a Palladium-Catalyzed Glycosylation

The enantioselective syntheses of daumone and two analogues have been achieved in seven to eight steps. This route relies upon a diasteroselective palladium-catalyzed glycosylation reaction for the formation of the anomeric bond. The asymmetry of the sugar and aglycone portion of daumone were introduced by Noyori reduction of an acylfuran and a propargyl ketone. A highly diastereoselective epoxidation and reductive ring opening established the desired C-2 and C-4 stereochemistry of daumone. [reaction: see text]