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首页> 外文期刊>Chemistry: A European journal >Asymmetric, Regioselective Direct Aldol Coupling of Enones and Aldehydes with Chiral Rhodium(bis-oxazolinylphenyl) Catalysts
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Asymmetric, Regioselective Direct Aldol Coupling of Enones and Aldehydes with Chiral Rhodium(bis-oxazolinylphenyl) Catalysts

机译：烯酮和醛与手性铑（双-恶唑啉基苯基）催化剂的不对称，区域选择性直接羟醛偶联

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The asymmetric direct aldol coupling reactions of ketones as enolate sources have been extensively developed by the use of chiral organocatalysts via in situ generated enamine species to provide optically active b-hydroxyketones efficiently. [ 1] However, among the candidate ketone substrates, acyclic and cyclic enones as enolate sources have rarely been applied because of problems of instability, as well as the ability for enones to act as reactive acceptors in conjugate additions, the possibility of retro-aldol equilibrium, or b-hydroxy elimination from the aldol products. It is clearly of importance that the vinylogous unsaturated aldol products derived from enones possess high potential to serve as useful components for organic synthesis. In 2005, Trost et al. first disclosed a potent catalyst based on a dinuclear Zn complex for the asymmetric direct aldol coupling of substituted aliphatic aldehydes with methyl vinyl ketone (MVK) as an enolate source with up to 98% enantiomeric excess (ee) (Scheme 1).[2] Nevertheless, there is still a challenge in terms of the scope of the substrate ketones. On the other hand, in terms of similar vinylogous aldol couplings, versatile methods that use silyl-protected dienolates have been successfully developed to give multifunctional unsaturated compounds.[3] In addition, the egioselective direct aldol coupling of enones is thought to be a romising approach to the synthesis of the corresponding unsaturated aldol products.
机译：通过使用手性有机催化剂经由原位生成的烯胺类物质广泛地开发了酮作为烯醇化物来源的不对称直接醛醇偶联反应，以有效地提供光学活性的b-羟基酮。 [1]然而，在候选的酮底物中，由于不稳定性的问题以及烯酮在共轭加成中充当反应性受体的能力，以及逆醛醇的可能性，很少使用无环和环状烯酮作为烯醇化物来源。平衡，或从羟醛产物中消除b-羟基。显然重要的是，衍生自烯酮的乙烯基不饱和醛醇缩醛产物具有用作有机合成有用组分的高潜力。在2005年，Trost等人。首先公开了一种基于双核锌配合物的有效催化剂，用于取代的脂肪族醛与甲基乙烯基酮（MVK）作为烯醇盐源的不对称直接羟醛偶联，对映体过量（ee）高达98％（方案1）。[2]然而，就底物酮的范围而言仍然存在挑战。另一方面，就类似的乙烯基醇醛醇盐偶联剂而言，已经成功开发了使用甲硅烷基保护的二烯酸酯的通用方法，从而可以得到多功能的不饱和化合物。[3]另外，烯酮的血管选择性的直接羟醛直接偶合被认为是合成相应的不饱和羟醛产物的渐进方法。

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