This grant application describes a program directed towards the total synthesis of the novel thiopeptide antibiotic thiostrepton. Produced by several bacterial strains including streptomyces azureus, this naturally-occurring substance is characterized by a novel molecular architecture which includes three highly complex molecular domains: a didehydropiperidine ring system possessing a quaternary center bearing three carbons and a nitrogen; a potentially sensitive thiazoline ring; and a unique quinaldic acid system. The originally proposed total synthesis will feature not only a highly convergent and flexible approach to the assembly of thiostrepton, but moreover the projected route will end with three novel cyclization reactions to complete the most challenging portions of the molecule. Moreover and given the daring nature of this bold approach an alternative, safer strategy for the construction of the macrocyclic rings is proposed. As such, this work is expected to impact positively the areas of new synthetic methodologies and strategies for complex molecule construction. Furthermore, the use of synthesized fragments and thiostrepton itself as chemical biology tools to probe the interactions of small molecules with RNA should help set the stage for drug discovery programs utilizing small organic compounds to selectively target RNA or RNA-protein complexes. The disease areas likely to benefit most from the proposed investigations are bacterial-caused diseases and malaria.
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