Regio- and enantiospecific rhodium-catalyzed arylation of unsymmetrical fluorinated acyclic allylic carbonates: inversion of absolute configuration
Regio- and enantiospecific rhodium-catalyzed arylation of unsymmetrical fluorinated acyclic allylic carbonates: inversion of absolute configuration
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DOI：
10.1021/ja035216q
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发表时间：
2003-06-18
影响因子：
15
通讯作者：
Uraguchi, D
中科院分区：
文献类型：
--
作者：
Evans, PA;Uraguchi, D
过渡金属催化的不稳定碳亲核试剂的烯丙基取代反应是构建三元碳立体异构中心的重要交叉偶联反应。我们开发了一种新的区域和对映体特异性铑催化的无环十一烷手性非外消旋烯丙醇衍生物与芳基溴化锌的烯丙基烷基化反应。这项研究表明，氢化三（吡唑基）硼酸铑催化剂和卤化锌（II）盐的效率是至关重要的，而加入溴化锂的催化剂是必要的，以获得最佳的区域特异性。通过合成（S）-布洛芬建立了该反应的立体化学过程，这表明烷基化进行时绝对构型发生净转化，这与亲核试剂直接加成到金属中心，然后还原消除一致。
The transition metal-catalyzed allylic substitution with unstabilized carbon nucleophiles represents an important cross-coupling reaction for the construction of ternary carbon stereogenic centers. We have developed a new regio- and enantiospecific rhodium-catalyzed allylic alkylation of acyclicunsymmetricalchiral nonracemic allylic alcohol derivatives with aryl zinc bromides. This study demonstrates that the hydrotris(pyrazolyl)borate rhodium catalyst and zinc(II) halide salt are crucial for efficiency, while the addition of lithium bromide to the catalyst is necessary for obtaining optimal regiospecificity. The stereochemical course of this reaction was established through the synthesis of (S)-ibuprofen, which demonstrated that the alkylation proceeds with net inversion of absolute configuration consistent with direct addition of the nucleophile to the metal center followed by reductive elimination.