Synthesis of (+)-Conagenin

• Published in: Journal of organic chemistry Vol. 70; no. 13; pp. 5339 - 5341
• Main Authors: Matsukawa, Yohei, Isobe, Minoru, Kotsuki, Hiyoshizo, Ichikawa, Yoshiyasu
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 24-06-2005
• Subjects: Aliphatic compounds; Catalysis; Chemistry; Exact sciences and technology; Indicators and Reagents; Molecular Structure; Organic chemistry; Preparations and properties; Serine - analogs & derivatives; Serine - chemical synthesis; Stereoisomerism; Organic isocyanate; Chemical synthesis; Organic cyanate; Triol; Aminoacid
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo050407s

An efficient total synthesis of (+)-conagenin was achieved. The right fragment of conagenin, α-methylserine containing a quaternary stereocenter attached to nitrogen, was synthesized using allyl cyanate-to-isocyanate rearrangement. The left fragment, 2,4-dihydroxy-3-methylpentanoic acid, has three contiguous stereogenic centers, which was efficiently constructed by enantioselective monoreduction of 2-alkyl-1,3-diketones reported by Cossy, and chelation-controlled stereoselective reduction of β-hydroxy ketone. These two fragments were coupled through intramolecular amide bond formation with high efficiency.