title: Studies on the synthesis of landomycin A. Synthesis of the originally assigned structure of the aglycone, landomycinone, and revision of structure.
abstract: The originally proposed structure (2) of landomycinone, the aglycone of landomycin A, has been synthesized and shown to be nonidentical to the naturally derived landomycin A aglycone. The synthesis of 2 features the Dötz benzannulation reaction of chromium carbene 5 and alkyne 6, and the intramolecular Michael-type cyclization reaction of the phenolic naphthoquinone 20. It is proposed that natural landomycinone possesses the alternative structure 3, but attempts to access this structure via the Michael-type cyclization of the isomeric phenolic naphthoquinone 38 have been unsuccessful.
authors.affiliation: Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA. roush@umich.edu
authors.forename: William R
authors.initials: WR
authors.lastname: Roush
authors.forename: R Jeffrey
authors.initials: RJ
authors.lastname: Neitz
mesh_terms: D000617:Aminoglycosides / Q000138:chemical synthesis* / Q000737:chemistry*; D002240:Carbohydrate Sequence; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D009285:Naphthoquinones / Q000138:chemical synthesis* / Q000737:chemistry*; D009844:Oligosaccharides / Q000138:chemical synthesis* / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000617:Aminoglycosides; D009285:Naphthoquinones; D009844:Oligosaccharides; C490012:anhydrolandomycinone; C490011:landomycinone; C064648:landomycin A