Synthesis of (+)-conagenin.
An efficient total synthesis of (+)-conagenin was achieved. The right fragment of conagenin, alpha-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 beta-hydroxy ketone. These two fragments were coupled through intramolecular amide bond formation with high efficiency.
Matsukawa
Yohei
Y
Laboratory of Natural Products, Faculty of Science, Kochi University, Akebono-cho, Kochi 780-8520, Japan.
Isobe
Minoru
M
Kotsuki
Hiyoshizo
H
Ichikawa
Yoshiyasu
Y
D002384:Catalysis; D007202:Indicators and Reagents; D015394:Molecular Structure; D012694:Serine / Q000031:analogs & derivatives* / Q000138:chemical synthesis*; D013237:Stereoisomerism
D007202:Indicators and Reagents; C069645:conagenin; D012694:Serine