Total Synthesis of (+)-Himbacine and (+)-Himbeline.

Journal Article (Journal Article)

Himbacine (1), a complex piperidine alkaloid isolated from the bark of Australian magnolias, is a promising lead in Alzheimer's disease research due to its potent muscarinic receptor antagonist property. We have described here a highly efficient synthetic strategy that resulted in the total synthesis of himbacine (1) in about 10% overall yield and isohimbacine (1a), an unnatural isomer of himbacine, in 18% overall yield. The total synthesis of himbacine was initially approached using an intramolecular Diels-Alder reaction as the key step to generate intermediate 5 followed by a [3 + 2] cycloaddition with nitrone 4 to produce the isoxazolidine derivative 3. Methylation followed by catalytic reduction of 3 gave 12'-hydroxyhimbacine (20), which, upon dehydration, gave isohimbacine (1a) as the sole product. In an alternative approach, an all-encompassing intramolecular Diels-Alder reaction of an appropriately substituted tetraene derivative 31, which bears the entire latent carbon framework and functional group substitution of himbacine, gave the desired advanced tricyclic intermediate 33, which was readily converted to (+)-himbeline (2) and (+)-himbacine (1).

Full Text

Duke Authors

Cited Authors

  • Chackalamannil, S; Davies, RJ; Wang, Y; Asberom, T; Doller, D; Wong, J; Leone, D; McPhail, AT

Published Date

  • March 1999

Published In

Volume / Issue

  • 64 / 6

Start / End Page

  • 1932 - 1940

PubMed ID

  • 11674285

Electronic International Standard Serial Number (EISSN)

  • 1520-6904

International Standard Serial Number (ISSN)

  • 0022-3263

Digital Object Identifier (DOI)

  • 10.1021/jo981983+

Language

  • eng