Catalytic enantioselective synthesis of oxindoles and benzofuranones that bear a quaternary stereocenter
Catalytic enantioselective synthesis of oxindoles and benzofuranones that bear a quaternary stereocenter
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DOI：
10.1002/anie.200351666
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发表时间：
2003-01-01
影响因子：
16.6
通讯作者：
Fu, GC
中科院分区：
文献类型：
--
作者：
Hills, ID;Fu, GC
在第一部分中，我们讨论了一种新的方法来构建具有四元立构中心的羟吲哚和苯并呋喃酮。平面手性PPY衍生物以高效和对映选择性的方式催化O-至-C酰基迁移（Black重排）。天然产物aplysin的正式全合成进一步证明了该方法的实用性。第二部分讨论了双膦钯配合物的反应活性。结果表明，含P（t-Bu）Me的双膦钯配合物的氧化加成反应是通过SN 2型机理进行的。这一发现使我们能够合理化Pd（P（t-Bu）Me）d2和Pd（P（t-Bu）Et）d2在烷基亲电试剂的交叉偶联中的催化活性差异。本文还讨论了双膦钯氢化物中H-X的还原消除反应。用X-射线晶体结构解释了（P（t-Bu）<$）<$PdHCl在Cy <$NMe存在下容易还原消除而（PCy <$）<$PdHCl不发生还原消除的发现。这些反应模式可能有助于解释为什么Pd（P（t-Bu）d3）d4是比Pd（PCy d3）d4更好的催化剂用于芳基氯的Heck偶联。最后，第三部分介绍了钯氢化物催化的烯丙醇异构化的初步工作，以及初步尝试研究镍催化的仲烷基亲电试剂的交叉偶联的机制。
In Part I the development of a new method for the construction of oxindoles and benzofuranones bearing quaternary stereocenters is discussed. A planar-chiral PPY derivative catalyzes the O-to-C acyl group migration (Black rearrangement) in a highly efficient and enantioselective manner. The utility of this method is further demonstrated by the formal total synthesis of the natural product aplysin. In Part II reactivity of bisphosphine palladium-complexes is discussed. It is shown that the oxidative addition of bisphosphine palladium-complexes bearing P(t-Bu₂)Me occurs through an SN2-type mechanism. This discovery allows us rationalize the difference in catalytic activity between Pd(P(t-Bu₂)Me)₂ and Pd(P(t-Bu₂)Et)₂ for the cross-coupling of alkyl electrophiles. The reductive elimination of H-X from bisphosphine palladium-hydride complexes is also discussed. The discovery that (P(t-Bu)₃)₂PdHCl undergoes facile reductive elimination in the presence of Cy₂NMe, while (PCy₃)₂PdHCl does not, is explained using X-ray crystal structures. These reactivity patterns may help to explain why Pd(P(t-Bu)₃)₂ is a much better catalyst than Pd(PCy₃)₂ for the Heck coupling of aryl chlorides. Finally, Part III describes preliminary work on a palladium-hydride catalyzed isomerization of allylic alcohols as well as initial attempts to study the mechanism of nickel-catalyzed cross-couplings of secondary alkyl-electrophiles.