Asymmetric reduction of 2,2-dimethyl-6-(2-oxoalkyl/oxoaryl)-1,3-dioxin-4-ones and application to the synthesis of (+)-yashabushitriol

The asymmetric transfer hydrogenation of a series of 2,2-dimethyl-6-(2-oxoalkyl)-1,3-dioxin-4-ones and 2,2-dimethyl-6-(2-oxoaryl)-1,3-dioxin-4-ones was achieved in high enantiomeric excess using a Ru(II) catalyst. The aryl substrates were most compatible with the methodology and this process facilitated a total synthesis of enantiomerically pure (+)-yashabushitriol

Catalyst-Controlled Stereoselective Olefin Metathesis as a Principal Strategy in Multistep Synthesis Design: A Concise Route to (+)-Neopeltolide

Molybdenum-, tungsten-, and ruthenium-based complexes that control the stereochemical outcome of olefin metathesis reactions have been recently introduced. However, the complementary nature of these systems through their combined use in multistep complex molecule synthesis has not been illustrated. A concise diastereo- and enantioselective route that furnishes the anti-proliferative natural product neopeltolide is now disclosed. Catalytic transformations are employed to address every stereochemical issue. Among the featured processes are an enantioselective ring-opening/cross-metathesis promoted by a Mo monoaryloxide pyrrolide (MAP) complex and a macrocyclic ring-closing metathesis that affords a trisubstituted alkene and is catalyzed by a Mo bis(aryloxide) species. Furthermore, Z-selective cross-metathesis reactions, facilitated by Mo and Ru complexes, have been employed in the stereoselective synthesis of the acyclic dienyl moiety of the target molecule.National Institutes of Health (U.S.) (NIH grant GM-59426)National Institutes of Health (U.S.) (NIH grant GM-57212)AstraZeneca (Firm) (Graduate Fellowship)National Science Foundation (U.S.) (NSF award CHE-1362763

Recent Synthetic Studies Leading to Structural Revisions of Marine Natural Products

Because of the highly unique structures of marine natural products, there are many examples of structures that were originally proposed based on spectral analyses but later proven incorrect. In many cases, the total syntheses of the originally proposed structures of marine natural products has confirmed their incorrectness and the subsequent total syntheses of the newly proposed structures proved the revised structures. This review will show such cases appearing after 2005 and demonstrate how the true structures were elucidated

Natural Products from the Lithistida: A Review of the Literature since 2000

Lithistid sponges are known to produce a diverse array of compounds ranging from polyketides, cyclic and linear peptides, alkaloids, pigments, lipids, and sterols. A majority of these structurally complex compounds have very potent and interesting biological activities. It has been a decade since a thorough review has been published that summarizes the literature on the natural products reported from this amazing sponge order. This review provides an update on the current taxonomic classification of the Lithistida, describes structures and biological activities of 131 new natural products, and discusses highlights from the total syntheses of 16 compounds from marine sponges of the Order Lithistida providing a compilation of the literature since the last review published in 2002