A facile pathway to enantiomerically enriched 3-hydroxy-2-oxindoles: asymmetric intramolecular arylation of α-keto amides catalyzed by a palladium-DifluorPhos complex.
A facile pathway to enantiomerically enriched 3-hydroxy-2-oxindoles: asymmetric intramolecular arylation of α-keto amides catalyzed by a palladium-DifluorPhos complex.
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DOI：
10.1002/anie.201102158
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发表时间：
2011-08
影响因子：
--
通讯作者：
L. Yin;M. Kanai;M. Shibasaki
中科院分区：
文献类型：
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作者：
L. Yin;M. Kanai;M. Shibasaki
从卤化物和三氟甲磺酸酯到羰基化合物的有机基团转移反应是一种有用的C2 H2 C键形成转化。一个例子是铬介导的Nozaki-Hiyama-Kishi（NHK）反应，[1]其实用性已被许多复杂天然产物和生物活性化合物的全合成应用所证明。[2]需要化学计量的有毒铬盐--该反应的一个主要缺点--已经通过使用由Fürstner和Shi开发的催化氧化还原系统而被克服。[3]这一基本成就允许扩展到NHK反应的催化对映选择性变体。[4]尽管该催化体系与原始化学计量体系相比具有很大的优点，但对Mn 0和TMSCl的化学计量量的要求仍然与现代环境友好的合成有机化学的原理相冲突。[5]2000年，Yamamoto和他的同事报道了一种独特的外消旋反应，该反应可能满足上述需求;一种钯催化的分子内芳基转移反应，使用伯醇作为化学计量还原剂，从芳基碘和溴到酮。[6]这种合成有用的反应的催化不对称变体，使用最少的金属，尚未开发。结合我们对催化不对称合成具有芳基四取代碳中心的3-羟基-2-羟吲哚的持续兴趣，[7-12]我们开始了一个项目，通过修改Yamamoto的原始方案来开发α-酮酰苯胺的催化对映选择性分子内芳基化反应。[13]该反应的产物是多用途的手性合成产物，
Organic group-transfer reactions from halides and triflates to carbonyl compounds are a useful CÀC bond-forming transformation. An example is the chromium-mediated Nozaki–Hiyama–Kishi (NHK) reaction,[1] whose utility has been demonstrated by numerous applications to total syntheses of complex natural products and biologically active compounds.[2] The requirement for stoichiometric amounts of toxic chromium salts—a major drawback of this reaction—has been overcome by the use of a catalytic redox system developed by Fürstner and Shi.[3] This fundamental achievement allowed for extension to a catalytic enantioselective variant of the NHK reaction.[4] Despite the great advantages of the catalytic system compared to the original stoichiometric system, the requirements for stoichiometric amounts of Mn0 and TMSCl still conflicts with principles of modern, environmentally benign synthetic organic chemistry.[5] A catalytic asymmetric NHK-type (or Grignard/Barbier-type) reaction without the use of stoichiometric amounts of metals is therefore in high demand.In 2000, Yamamoto and co-workers reported a unique racemic reaction that would potentially satisfy the above demand; a palladium-catalyzed intramolecular aryl-transfer reaction from aryl iodides and bromides to ketones using a primary alcohol as the stoichiometric reductant.[6] A catalytic asymmetric variant of this synthetically useful reaction, with minimal use of metals, has yet to be developed. Combined with our ongoing interest in the catalytic asymmetric synthesis of 3-hydroxy-2-oxindoles with an arylic tetrasubstituted carbon center,[7–12] we began a project to develop a catalytic enantioselective intramolecular arylation reaction of α-keto anilides by modifying Yamamoto s original protocol.[13] The products of this reaction are versatile chiral synthetic