Synthesis of the alkaloid tyroscherin by an aldol/Curtius strategy

Antifungal profile against Candida auris clinical isolates of tyroscherin and its new analog produced by the deep-sea-derived fungal strain Scedosporium apiospermum FKJ-0499

A new antifungal compound, named N-demethyltyroscherin (1), was discovered from the static fungal cultured material of Scedosporium apiospermum FKJ-0499 isolated from a deep-sea sediment sample together with a known compound, tyroscherin (2). The structure of 1 was elucidated as a new analog of 2 by MS and NMR analyses. The absolute configuration of 1 was determined by chemical derivatization. Both compounds showed potent in vitro antifungal activity against clinically isolated Candida auris strains, with MIC values ranging from 0.0625 to 4 µg ml-1.

Organocatalyzed enantioselective desymmetrization of diols in the preparation of chiral building blocks

Desymmetrization of diols is a powerful tool to the synthesis of chiral building blocks. Among the different approaches to perform discrimination between both enantiotopic hydroxyl groups, the organocatalytic approach has gained importance in the last years. A diverse range of organocatalysts has been used to efficiently promote this enantioselective transformation and this Minireview examines the different contributions in this field.

Alkylative ring opening of N-methylaziridinium ions and a formal synthesis of tyroscherin

Alkylative ring-opening reactions of stable 2-substituted N-methylaziridinium ions proceeded with various alkyl- or arylmagnesium bromides in the presence of CuI to yield synthetically valuable and optically pure alkylated acyclic amines in a completely regio- and stereoselective manner. This was applied to a formal synthesis of the cytotoxic natural product tyroscherin.

Unexpected stereochemical tolerance for the biological activity of tyroscherin

Here we describe the concise syntheses of the 15 diastereomers and key analogs of the natural product tyroscherin. While systematic analysis of the analogs clearly demonstrated that the hydrocarbon tail is important for biological activity, structure-activity relationship studies of the complete tyroscherin diastereoarray revealed a surprisingly expansive stereochemical tolerance for the cytotoxic activity. Our results represent a departure from the tenet that biological activity is constrained to a narrow pharmacophore, and highlight the recently emerging appreciation for stereochemical flexibility in defining the essential structural elements of biologically active small molecules.

Total synthesis and biological evaluation of tyroscherin

The efficient synthesis and biological evaluation of both the reported and revised structures of tyroscherin have been achieved. Central to our synthesis is a cross metathesis reaction that generated the trans-olefin regioselectively. This synthetic strategy enabled the facile manipulation of tyroscherin stereochemistry, facilitating the generation of all 16 tyroscherin diastereomers and a photoactivatable tyroscherin-based affinity probe for future mode of action studies.

Synthesis of (2RS,8R,10R)-YM-193221 and an improved approach to tyroscherin, bioactive natural compounds from Pseudallescheria sp

Short-step syntheses of (2RS,8R,10R)-YM-193221 (1) and tyroscherin (2), which are biologically active compounds isolated from Pseudallescheria sp., were accomplished in six and eight steps from L-tyrosine. The relative stereochemistry of natural YM-193221 was determined to be 8R*,10R*.