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[摘要]：(Heterocyclic Compounds (One Hetero Atom)) Section The 3-oxygenated-cis-dialkyl-2,5-substituted THF system, present in several natural products, was prepd. with good selectivity by acidic cyclization of 5-alkene-1,2,4-triol derivs. The starting alkenol was obtained in few steps from a chiral cis-diol resulting from microbial oxidn. of bromobenzene. The study of the cyclization allowed the rationalization of all exptl. results by assuming a complete ionization at the allylic position and a model close to the one proposed by Labelle for homoallylic induction in five-membered ring closures. |
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