On the synthesis of protopine alkaloids

J Org Chem. 2007 Sep 14;72(19):7301-6. doi: 10.1021/jo071038y. Epub 2007 Aug 17.

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.

MeSH terms

  • Benzazepines / chemistry*
  • Benzophenanthridines / chemical synthesis*
  • Berberine Alkaloids / chemical synthesis*

Substances

  • Benzazepines
  • Benzophenanthridines
  • Berberine Alkaloids
  • protopine