Studies on the synthesis of landomycin A. Synthesis of the originally assigned structure of the aglycone, landomycinone, and revision of structure.
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.
Roush
William R
WR
Department of Chemistry, University of Michigan, Ann Arbor, MI 48109, USA. roush@umich.edu
Neitz
R Jeffrey
RJ
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
D000617:Aminoglycosides; D009285:Naphthoquinones; D009844:Oligosaccharides; C490012:anhydrolandomycinone; C490011:landomycinone; C064648:landomycin A