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首页> 外文期刊>Chemistry: A European journal >Chiral 2-endo-Substituted 9-Oxabispidines: Novel Ligands for Enantioselective Copper(II)-Catalyzed Henry Reactions
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Chiral 2-endo-Substituted 9-Oxabispidines: Novel Ligands for Enantioselective Copper(II)-Catalyzed Henry Reactions

机译：手性2-endo取代9-Oxabispidines：对映选择性铜（II）催化亨利反应的新型配体。

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摘要

A flexible approach, applicable on a gram scale, to chiral 2-endo-substituted 9-oxabispidines was developed. The key intermediate, a cis-configured 6-aminomethylmorpholine-2-carbonitrile, was prepared from (R)-3-aminopropane-1,2-diol and 2-chloroacrylonitrile. The 2-endo substituent was introduced by Grignard addition, cyclization, and exo-selective reduction, thus furnishing the enantiomerically pure bi- and tricyclic 9-oxabispidines in 19-59% yield. The CuCl, complex of the tricyclic 9-oxabispidine, which carries an 2-endo,N-anellated piperidine ring, is an excellent catalyst for enantioselective Henry reactions giving the S-configured beta-nitro alcohols in 91-98% ee (13 examples). Surprisingly, the analogous copper complexes of the bicyclic 9-oxabispidines delivered the enantiocomplementary R-configured products in 33-57% ee. The respective transition states were discussed.
机译：开发了一种灵活的方法，适用于以克为单位的手性2-内-取代的9-氧杂sp啶。由（R）-3-氨基丙烷-1，2-二醇和2-氯丙烯腈制备关键中间体，顺式构型的6-氨基甲基吗啉-2-腈。通过Grignard加成，环化和外切选择性还原引入2-内基取代基，从而以19-59％的收率提供对映体纯的双环和三环9-氧杂萘啶。三环9-氧杂-啶的配合物CuCl带有2-内-N-芳基哌啶环，是对映选择性亨利反应的极佳催化剂，可在91-98％ee中得到S构型的β-硝基醇（13个例子）。出人意料的是，双环9-氧杂双吡啶的类似铜络合物以33-57％ee的对映体互补R-构型的产物。讨论了各自的过渡状态。

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