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首页> 外文学位 >Mechanistic and stereochemical studies of photoinduced electron transfer cyclization reactions: The role of nitrogen. The aqueous Prins reaction and efforts towards the total synthesis of (+)-dactylolide.
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Mechanistic and stereochemical studies of photoinduced electron transfer cyclization reactions: The role of nitrogen. The aqueous Prins reaction and efforts towards the total synthesis of (+)-dactylolide.

机译：光致电子转移环化反应的机理和立体化学研究：氮的作用。 Prins水溶液反应并努力全合成（+）-二羟甲基内酯。

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摘要

A novel method for catalytic electron transfer initiated cyclization reaction for the formation of cyclic acyl aminals through a unique method of carbon-carbon sigma-bond activation has been developed. This new cyclization strategy employs a potent electrophile, generated by a photoinitiated single electron oxidation of a homobenzylic amide or t-butyl carbamate, which reacts with an appended nucleophile allowing for the formation of cyclic acyl aminals.*; The Lewis acid-surfactant-combined catalyst (LASC) was employed in a novel method for effecting intramolecular Prins cyclization reactions in water. Acetals of 1,2 and 1,3 di- and tri-substituted alcohols with a tethered allyl silane have been converted to 2,6-syn-tetratahydropyrans. The LASCs are generated in situ by the addition of cerium nitrate to a solution of sodium dodecylsulfate and acetal in water. A heterogeneous reaction environment is created in which the acetal is trapped within the hydrophobic core of the immediately generated micelle. Intramolecular Prins cyclization is catalyzed upon interaction of the acetal with Lewis acidic cerium cations located at the surface of the micelle. LASC mediated intramolecular Prins cyclization reactions are efficient, high yielding, and an environmentally benign method of generating 2,6- cis-tetrahydropyrans.*; A highly convergent route towards the total synthesis of the marine macrolide (+)-dactylolide is currently being pursued. The route involves the condensation of two highly functionalized segments of the molecule, an alpha,beta-unsaturated aldehyde and a 1,3-syn-diol, to form a cyclic alpha,beta-unsaturated acetal. Both enantiopure segments arise from vinylogous aldol reactions, providing the three necessary stereocenters. The key synthetic transformation involves intramolecular Prins cyclization of a cyclic alpha,beta-unsaturated acetal with a pendent allylsilane to provide the 2,6-cis-disubstituted-4-methylenetetrahydropyran core of the molecule efficiently and stereoselectively. Other key transformations include a completely trans selective selenoxide-selenate [2,3] sigmatropic rearrangement and the selective oxidation of a primary allylic alcohol in the presence of a secondary alcohol with Dess-Martin periodinane.*; *Please refer to dissertation for diagrams.
机译：开发了一种新颖的催化电子转移引发环化反应的新方法，该方法通过独特的碳-碳西格玛键活化方法形成环状酰基缩醛。这种新的环化策略采用强力亲电试剂，该亲电试剂是通过光引发高纯苄基酰胺或氨基甲酸叔丁酯的单电子氧化而产生的，该亲电子试剂与附加的亲核试剂反应，从而形成环状酰基缩醛。路易斯酸-表面活性剂复合催化剂（LASC）被用于一种新颖的方法来实现在水中的分子内Prins环化反应。具有拴系的烯丙基硅烷的1,2和1,3二和三取代醇的缩醛已转化为2,6-syn-四氢吡喃。 LASC是通过将硝酸铈添加到十二烷基硫酸钠和乙缩醛的水溶液中而原位产生的。在异质反应环境中，缩醛被捕获在立即产生的胶束的疏水核内。缩醛与位于胶束表面的路易斯酸性铈阳离子相互作用时，可催化分子内Prins的环化反应。 LASC介导的分子内Prins环化反应高效，高收率，是一种环境友好的生成2,6-顺式四氢吡喃的方法。目前正在寻求一种高度趋同的途径，以实现海洋大环内酯（+）-环己内酯的全合成。该途径涉及分子的两个高度官能化的链段，即α，β-不饱和醛和1，3-syn-二醇的缩合，以形成环状的α，β-不饱和缩醛。两个对映纯链段均来自乙烯基醛醇缩合反应，提供了三个必要的立体中心。关键的合成转化过程涉及用悬垂的烯丙基硅烷对环状α，β-不饱和缩醛进行分子内Prins环化反应，以有效和立体选择性地提供分子的2,6-顺式-二取代的-4-亚甲基四氢吡喃核心。其他关键的转化包括完全反式的硒酸硒酸硒酸盐[2,3]σ重排，以及在仲醇与戴斯-马丁高碘烷的存在下伯烯丙基醇的选择性氧化。 *请参考论文的图表。

著录项

  • 作者

    Aubele, Danielle L.;

  • 作者单位

    University of Pittsburgh.;

  • 授予单位 University of Pittsburgh.;
  • 学科 Chemistry Organic.
  • 学位 Ph.D.
  • 年度 2004
  • 页码 344 p.
  • 总页数 344
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 有机化学;
  • 关键词

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