Syntheses of 3-O-Demethylthalicthuberine and N-Acetyl-seco-N-methyllaurotetanine

• Main Authors: Rujee Lorpitthaya, Surachai Nimgirawath, Jumrern Laosriratana
• Format: Article
• Language: English
• Published: Prince of Songkla University 2006-11-01
• Series: Songklanakarin Journal of Science and Technology (SJST)
• Subjects: alkaloid; aporphine; phenanthrene; synthesis; radical cyclization
• Online Access: http://www.sjst.psu.ac.th/journal/28_6_pdf/08-alkaloid.pdf

The structures previously assigned to the phenanthrene alkaloids 3-O-demethylthalicthuberine and N-acetyl-seco-N methyllaurotetanine have been confirmed by total syntheses in which the key step involved formation of ring C of the aporphine alkaloids (±)-isodomesticine and O-benzyl-N-methyllaurotetanine by a radical-initiated cyclization. Opening of ring B of (±) isodomesticine with methyl chloroformate and subsequent reduction of the N-carbomethoxy group afforded 3-O demethylthalicthuberine. Similarly, ring-B opening of N-methyllaurotetanine with acetyl bromide followed by hydrolysis afforded N-acetyl-seco-Nmethyllaurotetanine.