title: Synthesis of Breitfussin B by Late-Stage Bromination.
abstract: The breitfussins are halogenated natural products whose structures were determined with the assistance of atomic-force microscopy. The site selectivity of N-bromosuccinimide-mediated bromination of a model breitfussin core was found to be strongly dependent on solvent selection; use of acetone led to oxazole bromination, and use of a pyridine-containing mixture led to pyrrole bromination. This tunable site-selective bromination was used in a protecting-group-free synthesis of breitfussin B that proceeded in 9.2% yield over 12 reactions and five chromatographic separations. A bromooxazole analogue of breitfussin A was also prepared by late-stage bromination but isomerized on silica gel to form breitfussin B. This isomerization appeared to proceed through a unimolecular pathway.
authors.affiliation: Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States.
authors.forename: Akbar H
authors.initials: AH
authors.lastname: Khan
authors.affiliation: Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States.
authors.forename: Jason S
authors.initials: JS
authors.lastname: Chen
mesh_terms: D001688:Biological Products / Q000138:chemical synthesis* / Q000737:chemistry; D001974:Bromosuccinimide / Q000737:chemistry; D006842:Hydrocarbons, Brominated / Q000138:chemical synthesis* / Q000737:chemistry; D007211:Indoles / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D011725:Pyridines / Q000737:chemistry*; D011758:Pyrroles / Q000737:chemistry
chemical_list: D001688:Biological Products; D006842:Hydrocarbons, Brominated; D007211:Indoles; D011725:Pyridines; D011758:Pyrroles; C000595760:breitfussin B; D001974:Bromosuccinimide