Asymmetric Total Synthesis of Streptoglycerides A and B

Abstract A unified strategy for the asymmetric total synthesis of streptoglycerides A and B has been established and has confirmed their proposed absolute configurations. Key to our strategy is the synthesis of a bicyclic scaffold, employing a gold-catalyzed cascade cyclization of 1,6-diyn-ol operating through a 6-endo/5-exo-dig mechanism and its one-pot dihydroxylation followed trans-glycosylation to forge the central tricyclic core of these natural products. Noyori’s asymmetric transfer hydrogenation of an α, β-acetylenic ketones has been employed to install the key propargyl alcohol center with the desired absolute configuration. The pendant conjugated trans-1,3,5-triene/trans-1,3-diene side chains were introduced from a propanaldehyde unit following [Pd]-catalyzed oxidative dehydrogenation, Takai olefination, and Stille cross-coupling.