期刊
ORGANIC & BIOMOLECULAR CHEMISTRY
卷 7, 期 12, 页码 2628-2634出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/b901965k
关键词
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资金
- Ministry of Science and Technology [2009CB724704, 2006CB806106]
- National Natural Science Foundation of China [20772132, 20820102034]
- Chinese Academy of Sciences
The synthesis of both antipodes of N-methyl-N-[(Z)-styryl]-3-phenyloxirane-2-carboxamide (SB204900), clausenamide, neoclausenamide, homoclausenamide and zeta-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 zeta-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 degrees C led to the epimerization of neoclausenamidone into clausenamidone. Reduction of clausenamidone using NaBH4 furnished clausenamide in high yield.
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