Epoxy tert-alcohols have been prepared from (E)-enones in a two-step approach consisting of JuliáColonna asymmetric epoxidation followed by Grignard alkylation of the epoxyketone. On treatment with sub-stoichiometric amounts of Yb(OTf)3 these trans-epoxyalcohols underwent efficient stereoselective semi-pinacol rearrangement to afford anti-α-phenyl-β-hydroxy-ketones (aldols). Under the same conditions, spirocyclic epoxyalcohols derived from 1-tetralone and 1-benzosuberone undergo either ring contraction (via semi-pinacol rearrangement) or fragmentation. A mechanistic rationale is presented to explain the formation of the various products.Key words: JuliáColonna reaction, asymmetric epoxidation, epoxy tert-alcohols, semi-pinacol rearrangement.
环氧叔醇是从(E)-烯酮中制备的,采用两步法:首先进行Juliá-Colonna不对称环氧化,然后进行环氧酮的Grignard烷基化。在亚化学计量的Yb(OTf)3处理下,这些反式环氧醇经历了高效立体选择性的半皮纳科尔重排反应,生成反式-α-苯基-β-羟基酮(醛醇)。在相同条件下,由1-四氢萘酮和1-苯基萘酮制备的螺环氧醇会经历环收缩(通过半皮纳科尔重排)或裂解。提出了一个机理解释来解释各种产物的形成。关键词:Juliá-Colonna反应,不对称环氧化,环氧叔醇,半皮纳科尔重排。