Asymmetric synthesis from terminal alkenes by cascades of diboration and cross-coupling.
Asymmetric synthesis from terminal alkenes by cascades of diboration and cross-coupling.
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在有机合成的潜在起始原料中，末端（单取代）烯烃是理想的。以α-烯烃的形式，它们以巨大的规模生产，并且它们是许多有机化学反应的核心产物特征。虽然它们的潜在反应性可以容易地使烃链增长，但烯烃也具有在许多酸、碱、氧化剂和还原剂存在下稳定的吸引人的特征。尽管这些令人印象深刻的属性，相对较少的催化对映选择性转化已经开发，转化脂肪族α-烯烃在> 90%ee，除了α-烯烃的位点控制的全同立构聚合，这些方法都没有导致链延伸的C-C键形成到末端碳。在此，我们描述了一种策略，直接解决了这一差距，在合成方法和目前的单瓶催化末端烯烃的对映选择性转化成一系列的手性产品。这些反应是由一个不寻常的相邻基团参与效应，加速钯催化的交叉偶联的1，2-双（硼酸酯）相对于非官能化的烷基硼酸酯类似物。与对映选择性二硼化反应相结合，这种反应性特征将丰富的烯烃起始材料连接到各种手性产物。关于合成实用性重要的是，串联二硼化/交叉偶联反应（DCC反应）通常以高产率和高选择性（>95：5对映异构体比率）提供产物，采用低负载量（1-2摩尔%）的市售催化剂和试剂，其提供了广阔的底物范围，并且可以解决宽范围的醇和胺合成目标，其中许多目标不能用现有技术容易地解决。
Amongst prospective starting materials for organic synthesis, terminal (monosubstituted) alkenes are ideal. In the form of α-olefins, they are manufactured on enormous scale and they are the core product features from many organic chemical reactions. While their latent reactivity can easily enable hydrocarbon chain extension, alkenes also have the attractive feature of being stable in the presence of many acids, bases, oxidants and reductants. In spite of these impressive attributes, relatively few catalytic enantioselective transformations have been developed that transform aliphatic α-olefins in >90% ee and, with the exception of site-controlled isotactic polymerization of α-olefins, none of these processes result in chain-extending C-C bond formation to the terminal carbon. Herein, we describe a strategy that directly addresses this gap in synthetic methodology and present a single-flask catalytic enantioselective conversion of terminal alkenes into a range of chiral products. These reactions are enabled by an unusual neighboring group participation effect that accelerates Pd-catalyzed cross-coupling of 1,2-bis(boronates) relative to nonfunctionalized alkyl boronate analogs. In tandem with enantioselective diboration, this reactivity feature connects abundant alkene starting materials to a diverse array of chiral products. Importantly with respect to synthesis utility, the tandem diboration/cross-coupling reaction (DCC reaction) generally provides products in high yield and high selectivity (>95:5 enantiomer ratio), employs low loadings (1–2 mol %) of commercially available catalysts and reagents, it offers an expansive substrate scope, and can address a broad range of alcohol and amine synthesis targets, many of which cannot be easily addressed with current technology.
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影响因子：
3.6
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