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Chiral relay: A promising strategy in enantioselective catalysis.

机译：手性中继：对映选择性催化的一种有前途的策略。

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摘要

A relatively new strategy in enantioselective catalysis is the relay of stereochemical information from (a) permanent chiral center(s) to a transient or fluxional chiral center. The transient or fluxional chiral center may serve to amplify the inherent asymmetric induction provided by the permanent chiral center(s) or function as the primary stereocontrol element. This strategy is now commonly referred to as "chiral relay" and has been employed in the development of chiral relay auxiliaries, ligands, and additives. Applications of chiral relay templates are discussed in the context of enantioselective Diels-Alder, nitrile imine, and diazoacetate cycloadditions in the following chapters. An application of chiral relay ligands in diethylzinc additions to aldehydes is also discussed.;Chapter 1. A study on the role of alpha,beta-unsaturated pyrazolidinone templates in enantioselective Diels-Alder reactions is discussed. The key issues addressed are the impact of N-1 and C-5 substitution on enantioselectivity, the influence of metal geometry on the relay of stereochemical information from the chiral ligand to the pyrazolidinone template, and conformational/mechanistic insights.;Chapter 2. Chiral relay ligands based on a novel pyrazole scaffold are developed for application in enantioselective diethylzinc additions to aldehydes. The key issues approached include the effect of fluxional and permanent chirality on enantioselectivity, and the interplay between these two stereocontrol elements.;Chapter 3. The first catalytic, enantioselective methodology for 1,3-dipolar cycloadditions of nitrile imines is developed for the synthesis of chiral N-aryl dihydropyrazoles. The ability to control rotamer geometry in alpha-substituted and alpha,beta-disubstituted alpha,beta-unsaturated pyrazolidinone imides is also demonstrated.;Chapter 4. Enantioselective 1,3-dipolar cycloadditions of diazoacetates to alpha,beta-unsaturated pyrazolidinone imides are developed to synthesize enantioenriched Delta2-pyrazolines. The cycloaddition methodology is successfully applied to an enantioselective total synthesis of (--)-manzacidin A.;Chapter 5. The Sibi group's design and application of achiral auxiliaries are reviewed. The role of achiral auxiliaries in the development of enantioselective radical conjugate addition; amine conjugate addition; Diels-Alder cycloaddition; and 1,3-dipolar cycloaddition methodologies is the focus of the review.
机译：对映选择性催化的一种相对较新的策略是将立体化学信息从一个或多个永久性手性中心传递至一个瞬态或流动性手性中心。瞬态或通量手性中心可以用来放大由一个或多个永久手性中心提供的固有的不对称感应，或者用作主要的立体控制元件。这种策略现在通常被称为“手性中继”，并已用于手性中继助剂，配体和添加剂的开发中。在接下来的章节中，将在对映选择性Diels-Alder，腈亚胺和重氮乙酸酯环加成的背景下讨论手性中继模板的应用。还讨论了手性中继配体在醛中二乙基锌加成中的应用。第一章，研究α，β-不饱和吡唑烷酮模板在对映选择性Diels-Alder反应中的作用。解决的关键问题是N-1和C-5取代对对映选择性的影响，金属几何形状对从手性配体到吡唑烷酮模板的立体化学信息的传递的影响，以及构象/机理的见解。；第2章。开发了一种基于新型吡唑骨架的中继配体，用于对醛的对映选择性二乙基锌加成。解决的关键问题包括通量和永久手性对对映体选择性的影响，以及这两个立体控制元素之间的相互作用。；第3章。开发了第一种催化腈对映体的对映选择性方法，用于腈亚胺的1,3-偶极环加成反应。手性N-芳基二氢吡唑类。还证明了在α-取代的和α，β-二取代的α，β-不饱和吡唑烷酮酰亚胺中控制旋转异构体几何形状的能力。；第4章。开发了重氮酸酯与α，β-不饱和吡唑烷酮酰亚胺的对映选择性1,3-偶极环加成反应。合成对映体富集的Delta2-吡唑啉。环加成方法已成功地应用于（-）-甘露酸A.的对映选择性全合成。第5章。综述了Sibi集团的非手性助剂的设计和应用。非手性助剂在对映选择性自由基共轭加成反应中的作用；胺共轭加成; Diels-Alder环加成； 1,3-偶极环加成方法学是本综述的重点。

著录项

  • 作者

    Stanley, Levi Michael.;

  • 作者单位

    North Dakota State University.;

  • 授予单位 North Dakota State University.;
  • 学科 Chemistry Organic.
  • 学位 Ph.D.
  • 年度 2007
  • 页码 353 p.
  • 总页数 353
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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