title: On the synthesis of protopine alkaloids.
abstract: For the synthesis of protopine alkaloids, we studied a reaction sequence based on a ring enlargement of indeno[2,1-a][3]benzazepines by a singlet oxygen oxygenation, followed by conversion of an amide carbonyl group of the resultant 10-membered keto-lactam to a methylene group, which is the last step for completion of the synthesis. The key substances, indeno[2,1-a][3]benzazepines, were prepared by Bischler-Napieralski cyclization of alkoxy-substituted 1-(2-bromobenzyl)-3-benzazepin-2-ones. Steric effects of the substituents in this synthesis were examined.
authors: Laboratory of Organic Synthesis, Division of Molecular Chemistry, School of Engineering, Hokkaido University, Sapporo 060-8628, Japan.
authors: Yasuhiro
authors: Y
authors: Wada
authors: Harumi
authors: H
authors: Kaga
authors: Shiho
authors: S
authors: Uchiito
authors: Eri
authors: E
authors: Kumazawa
authors: Miho
authors: M
authors: Tomiki
authors: Yu
authors: Y
authors: Onozaki
authors: Nobuhito
authors: N
authors: Kurono
authors: Masao
authors: M
authors: Tokuda
authors: Takeshi
authors: T
authors: Ohkuma
authors: Kazuhiko
authors: K
authors: Orito
mesh_terms: D001552:Benzazepines / Q000737:chemistry*; D053119:Benzophenanthridines / Q000138:chemical synthesis*; D001600:Berberine Alkaloids / Q000138:chemical synthesis*
chemical_list: D001552:Benzazepines; D053119:Benzophenanthridines; D001600:Berberine Alkaloids; C009093:protopine