title: Synthesis of Angucyclines. 8. Biomimetic-Type Synthesis of Rabelomycin, Tetrangomycin, and Related Ring B Aromatic Angucyclinones.
abstract: The angucyclinones with aromatic ring B (1a-c and 2a-c) are prepared in a biomimetic-type synthesis by two successive aldol cyclizations starting from the substituted naphthoquinones 12a-c. In both cyclization steps the C-H acidity of the potential nucleophilic centers determines the mode of cyclization under kinetically controlled conditions. The tetrahydroanthraquinones 13a-c/14a-c are hydroxylated at C-4 to the phenolic anthraquinones 16a-c upon treatment with excess NMO.
authors.affiliation: Universität-GH-Paderborn, FB Chemie und Chemietechnik, Warburger Str. 100, 33098 Paderborn, Germany.
authors.forename: Karsten
authors.initials: K
authors.lastname: Krohn
authors.forename: Norbert
authors.initials: N
authors.lastname: Böker
authors.forename: Ulrich
authors.initials: U
authors.lastname: Flörke
authors.forename: Christian
authors.initials: C
authors.lastname: Freund