ChemInform Abstract: Syntheses of Strychnan- and Aspidospermatan-Type Alkaloids. Part 11. Total Syntheses of (-)-Lochneridine and (-)- and Racemic 20-epi-Lochneridine.

✍ Scribed by Martin E. Kuehne; Feng Xu

• Publisher: John Wiley and Sons
• Year: 2010
• Weight: 37 KB
• Volume: 30
• Category: Article
• ISSN: 0931-7597
• DOI: 10.1002/chin.199923244

✦ Synopsis

Syntheses of Strychnan-and Aspidospermatan-Type Alkaloids. Part 11. Total Syntheses of (-)-Lochneridine and (-)-and Racemic 20-epi-Lochneridine.

-The methods presented in the preceding article for the synthesis of strychnine are modified to prepare the title alkaloids. Pentacyclic ketone (I) forms in the presence of the soft Grignard reagent CeCl 3 lochneridine (III) with complete diastereoselectivity. Tetracycle (VII) is derived from the same precursor indole (IV) as is used for the strychnine synthesis. The hydrogenolysis of its N-benzyl substituent is achieved without epimerization by treatment with HCOONH 4 . Dihydroxylation of the Boc-protected tetracycle (IX) and final cyclization after the tosylation of primary and silylation of the tertiary hydroxy groups gives the target epi-lochneridine (XIV). -(KUEHNE,