| Abstract
| - An efficient total synthesis of (+)-conagenin was achieved.The right fragment of conagenin, α-methylserine containinga 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 of2-alkyl-1,3-diketones reported by Cossy, and chelation-controlled stereoselective reduction of β-hydroxy ketone.These two fragments were coupled through intramolecularamide bond formation with high efficiency.
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