- Highly efficient and concise synthesis of both antipodes of SB204900, clausenamide, neoclausenamide, homoclausenamide and ζ-clausenamide. Implication of biosynthetic pathways of clausena alkaloids
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The synthesis of both antipodes of N-methyl-N-[(Z)-styryl]-3-phenyloxirane- 2-carboxamide (SB204900), clausenamide, neoclausenamide, homoclausenamide and ζ-clausenamide have been accomplished using (2S,3R)- and (2R,3S)-3-phenyloxirane-2-carboxamides as the starting materials, and SB204900 was found to be a common precursor to other N-heterocyclic clausena alkaloids. Mediated by Bronsted acids under different conditions, for example, SB204900 underwent efficient and diverse alkene-epoxide cyclization, enamide-epoxide cyclization and arene-epoxide cyclization reactions to produce the five-membered N-heterocyclic neoclausenamide, its 6-epimer, the six-membered N-heterocyclic homoclausenamide and the eight-membered N-heterocyclic ζ-clausenamide, respectively, in good to excellent yields. Regiospecific oxidation of neoclausenamide and its 6-epimer afforded neoclausenamidone. Enolization of neoclausenamidone in the presence of LiOH and the subsequent protonation under kinetic conditions at -78 °C led to the epimerization of neoclausenamidone into clausenamidone. Reduction of clausenamidone using NaBH4 furnished clausenamide in high yield. The Royal Society of Chemistry 2009.
- Yang, Luo,Wang, De-Xian,Zheng, Qi-Yu,Pan, Jie,Huang, Zhi-Tang,Wang, Mei-Xiang
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scheme or table
p. 2628 - 2634
(2009/10/31)
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- Diastereoselective and Enantioselective Total Synthesis of the Hepatoprotective Agent Clausenamide
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The diastereoselective total synthesis of the naturally ocurring hepatoprotective agent clausenamide (3-hydroxy-5-(α-hydroxybenzyl)-1-methyl-4-phenylpyrrolidin-2-one) is described, starting from ethyl cinnamate and diethyl acetamidomalonate.The enantioselective total synthesis of optically pure (+)-clausenamide is presented.The synthesis is based on a novel method for the preparation of optically pure (2S,3S)-3-phenylglutamic acid.
- Hartwig, Wolfgang,Born, Liborius
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p. 4352 - 4358
(2007/10/02)
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