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[摘要]：Chiral heterocyclic structures based on 3-aminopyrrolidines, 3-aminotetrahydrothiophenes, and 3-aminotetrahydrofurans have been synthesized. The corresponding lithium amides have been evaluated as chiral ligands in the hydroxyalkylation of o-tolualdehyde with n-BuLi. The returned levels of induction were in the 46-80% ee range. The cheap and easily prepd. 3-aminotetrahydrofuran-based lithium amides turned out to be also the best ligands, giving access to the expected R or S alcs. in a same 80% level of induction at -78 癈 in THF. In all cases, the sense of induction depends on the abs. configuration of C8 on the 3-amino appendage. A general concept is proposed to rationalize the process of induction in the presence of organolithium species. |
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