Enantioselective synthesis of allylsilanes bearing tertiary and quaternary Si-substituted carbons through Cu-catalyzed allylic Alkylations with alkylzinc and arylzinc reagents
Enantioselective synthesis of allylsilanes bearing tertiary and quaternary Si-substituted carbons through Cu-catalyzed allylic Alkylations with alkylzinc and arylzinc reagents
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DOI：
10.1002/anie.200700841
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发表时间：
2007-01-01
影响因子：
16.6
通讯作者：
Hoveyda, Amir H.
中科院分区：
文献类型：
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作者：
Kacprzynski, Monica A.;May, Tricia L.;Hoveyda, Amir H.
烯丙基硅烷广泛应用于立体选择性有机合成。[1]设计和开发有效的催化不对称方法，提供高对映体纯度的手性烯丙基硅烷，将显着扩展这些多功能亲核试剂的用途。在此，我们报道了一种通过铜催化的硅取代不饱和磷酸酯与二烷基和二芳基锌试剂的不对称烯丙基烷基化（AAA）[2]对映选择性合成一系列烯丙基硅烷的有效方法[Eq.（1）]。 1–2.5 mol% 的手性 N-杂环卡宾基（NHC 基）催化剂可促进转化，并提供对映体富集的烯丙基硅烷，其 ee 高达 98%，产率超过 70%。提出了提供三级以及那些提供四级硅取代碳立构中心的催化不对称反应。据我们所知，本公开提出了第一个催化不对称合成带有甲硅烷基的季碳立构中心的方法，[3, 4]以及第一个利用芳基金属试剂的催化AAA。[5]已经开发了许多用于催化对映选择性合成烯丙基硅烷的方案。此类转化包括 1-(甲硅烷基)-烷基格氏试剂与卤乙烯的对映选择性偶联、[6] 1, 3-二烯的氢化硅烷化、[7] 烯丙氯的甲硅烷基化、[8] 氢化物加成到甲硅烷基取代的烯丙碳酸酯上、[9] 以及丙二烯的硅化反应。 [10]这些过程全部由 Pd 催化，主要涉及 C-Si 或 C-H 键的形成（交叉偶联反应除外）[11]，并以非外消旋形式提供一系列合成上有用的烯丙基硅烷。在
Allylsilanes are widely used in stereoselective organic synthesis.[1] Design and development of efficient catalytic asymmetric methods that furnish chiral allylsilanes in high enantiomeric purity would significantly expand the utility of these versatile nucleophiles. Herein, we report an efficient method for enantioselective synthesis of a range of allylsilanes by Cu-catalyzed asymmetric allylic alkylation (AAA)[2] of Si-substituted unsaturated phosphates with dialkyl-and diarylzinc reagents [Eq.(1)]. Transformations are promoted by 1–2.5 mol% of chiral N-heterocyclic carbene based (NHC-based) catalysts and afford enantiomerically enriched allylsilanes in up to 98% ee and over 70% yield. Catalytic asymmetric reactions that afford tertiary as well as those that deliver quaternary Si-substituted carbon stereogenic centers are presented. To the best of our knowledge, this disclosure puts forth the first method for catalytic asymmetric synthesis of quaternary carbon stereogenic centers that bear a silyl group,[3, 4] as well as the first catalytic AAA that utilizes arylmetal reagents.[5]A number of protocols for catalytic enantioselective synthesis of allylsilanes have been developed. Such transformations include enantioselective couplings of 1-(silyl)-alkyl Grignard reagents with vinyl halides,[6] hydrosilylations of 1, 3-dienes,[7] silylations of allylic chlorides,[8] hydride additions to silyl-substituted allylic carbonates,[9] and silaborations of allenes.[10] These processes, all Pd-catalyzed, largely involve formation of CÀSi or CÀH bonds (with the exception of cross-coupling reactions)[11] and deliver an array of synthetically useful allylsilanes in the non-racemic form. In