Indium(I)-Catalyzed Asymmetric Allylation, Crotylation, and α-Chloroallylation of Hydrazones with Rare Constitutional and High Configurational Selectivities
Indium(I)-Catalyzed Asymmetric Allylation, Crotylation, and α-Chloroallylation of Hydrazones with Rare Constitutional and High Configurational Selectivities
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DOI：
10.1002/anie.200906308
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发表时间：
2010-01-01
影响因子：
16.6
通讯作者：
Kobayashi, Shu
中科院分区：
文献类型：
--
作者：
Chakrabarti, Ananya;Konishi, Hideyuki;Kobayashi, Shu
主要金属族铟在催化方面的应用很有吸引力，因为铟基化合物毒性低，价格便宜，选择性强，对官能团具有耐受性。[1,2]虽然InIII路易斯酸通常用于催化，但由于两个空的质子（酸）和一对孤电子（碱），[3]InI化合物[4]可以显示两亲性，这取决于它们与之配位的配体尽管有这个有趣的特点，利用InI的合成是罕见的；在合成使用中通常需要超过化学计量量的InI试剂。[1,6]在早期的报道中，我们的研究小组发现了铟(I)催化的外消旋CÀC与烯丙基硼酸盐成键。在我们的研究过程中，核磁共振光谱分析揭示了通过催化B-to-In转金属反应生成反应性烯丙基i。[7b]同时，合适的InI连接对于结构或物理性质[8]和化学反应性的重要性[8j， k]也得到了证明。然而，据我们所知，手性i配合物及其催化不对称CÀC键形成的用途尚不清楚。催化非活化亚胺及其衍生物的不对称烯丙基化是具有挑战性的，但可以提供光富集的纯烯丙胺衍生物，这些衍生物已被证明是药物和农用化学品应用的有用的手性基石。利用Sn，[10] Si, b[11] B，[12]和原位制备的铟试剂开发了最有效的催化不对称方法不幸的是，很少有催化方法被发现是有效的、实用的或通用的。在这里，我们报道了一种前所未有的手性InI配合物催化在硼酸腙[14]和硼酸烯丙基之间不对称CÀC键形成。
The main group metal indium is appealing for use in catalysis, as indium-based compounds have low toxicity, and are inexpensive, selective, and tolerant toward functional groups.[1, 2] Although InIII Lewis acids are commonly used in catalysis,[3] InI compounds [4] can display amphiphilic properties depending on the ligands to which they are coordinated, owing to two vacant porbitals (acid) and a lone pair of electrons (base).[5] Despite this intriguing character, synthesis exploiting InI is rare; more than stoichiometric amounts of InI reagents are generally required in synthetic use.[1, 6] In earlier reports,[7] our research group uncovered indium (I)-catalyzed racemic CÀC bond formations with allyl boronates. In the course of our studies, NMR spectroscopic analyses revealed the generation of reactive allyl InI species through catalytic B-to-In transmetalation.[7b] Meanwhile, the importance of suitable InI ligation for both structural or physical properties [8] and chemical reactivity [8j, k] has been demonstrated. To the best of our knowledge, however, chiral InI complexes and their catalytic use for asymmetric CÀC bond formation are unknown.Catalytic asymmetric allylation of non-activated imines and their derivatives is challenging,[9] but can provide access to optically enriched homoallyl amine derivatives, which have proved to be useful chiral building blocks for pharmaceutical and agrochemical applications. Most powerful catalytic asymmetric methods have been developed using Sn,[10] Si,[11] B,[12] and in situ prepared indium reagents.[13] Unfortunately, very few catalytic methods were found to be efficient, practical, or general. Herein we report the catalytic use of an unprecedented chiral InI complex for asymmetric CÀC bond formations between hydrazones [14] and allyl boronates,