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首页> 外文学位 >Synthesis of the Tricyclic Core of Guanacastepene A, Decarboxylative Rearrangement of Allenylic N-Tosyl Carbamates and Phosphine-catalyzed Intramolecular gamma-Umpolung Addition of alpha-Aminoalkylallenic Esters, and the Enantioselective Total Synthesis of (+)-Ibophyllidine.
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Synthesis of the Tricyclic Core of Guanacastepene A, Decarboxylative Rearrangement of Allenylic N-Tosyl Carbamates and Phosphine-catalyzed Intramolecular gamma-Umpolung Addition of alpha-Aminoalkylallenic Esters, and the Enantioselective Total Synthesis of (+)-Ibophyllidine.

机译：瓜纳卡斯蒂芬A的三环核的合成，烯丙基N-甲苯基氨基甲酸酯的脱羧重排和膦催化的α-氨基烷基亚烷基酯的分子内γ-Umpolung加成，以及（+）-Ibophyllidine的对映选择性全合成。

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摘要

Chapter 1: The synthesis of the tricyclic core of the diterpene guanacastepene A is described. Based on previous studies in the laboratory of professor Ohyun Kwon, the densely functionalized six-membered ring of the natural product was constructed utilizing an intermolecular Diels-Alder cycloaddition between maleic anhydride and a highly substituted alkoxydiene. The requisite diene was synthesized via a Stille cross coupling reaction for which an efficient synthesis of the necessary vinyl stannane was developed. An alternative synthesis of the diene based on copper mediated coupling of vinyl boronates with alcohols was also devised, which allowed for the preparation of gram quantities with minimal purification. The five-membered ring of guanacastepene A was appended through coupling with a highly functionalized zinc cuprate. While previous studies in the Kwon laboratory showed that a conjugate addition/Mukaiyama aldol strategy to install the C11 methyl group and forge the seven-membered ring was efficient in forming the two desired carbon-carbon bonds, poor diastereoselectivity of the initial conjugate addition was observed. The research described here uses the Nozaki--Hiyama--Kishi reaction to close the central seven-membered ring without prior installation of the C11 methyl group.;Chapter 2: The synthesis of 3-carbethoxy-2-substituted-3-pyrrolines via the phosphine-catalyzed intramolecular gamma-umpolung addition of N-tosyl &agr;-aminoalkylallenic esters is described. The current transformation provides a compliment to the known syntheses of similarly substituted pyrrolines via the phosphine-catalyzed [3 + 2] annulation between imines and allenoates. The flexibility in substitution at the 2-position, including alkyl groups, offers benefits over many of the previously reported syntheses of similarly substituted pyrrolines. The N-tosyl &agr;-aminoalkylallenic esters were prepared via a novel decarboxylative rearrangement of allenylic carbamates.;Chapter 3: The enantioselective total synthesis of the monoterpene indole alkaloid (+)-ibophyllidine is described. The employed strategy was based on a key asymmetric phosphine-catalyzed [3 + 2] annulations between a gamma-ethyl allenoate and the N-tosyl imine derived from indole-3-aldehyde using Kwon's L-4-hydroxyproline-derived chiral phosphine catalyst. This key transformation constructed the stereochemically dense D-ring with exceptional levels of diastereo- and enantioselectivity. A subsequent diastereoselective hydrogenation of the pyrroline double bond led to the fully functionalized, all syn pyrrolidine ring of the natural product. An intramolecular alkylation at the C3 position of indole formed the C-ring while an intramolecular aza Baylis--Hillman reaction was utilized to forge the E-ring leading to the pentacyclic skeleton of (+)-ibophyllidine.
机译：第1章：描述了二萜鸟粪甲烯A的三环核的合成。根据权大Oh教授实验室中的先前研究，利用马来酸酐和高度取代的烷氧基二烯之间的分子间Diels-Alder环加成反应构建了天然产物的稠密官能化六元环。通过Stille交叉偶联反应合成了必需的二烯，为此开发了有效的乙烯基乙烯基锡的合成方法。还设计了基于铜介导的硼酸乙烯基酯与醇的偶联的二烯的替代合成，其允许以最少的纯化来制备克量。通过与高度官能化的铜酸锌偶合，将胍卡斯汀A的五元环连接起来。虽然Kwon实验室的先前研究表明，共轭加成/ Mukaiyama aldol策略可安装C11甲基并锻造七元环，可有效形成两个所需的碳-碳键，但观察到初始共轭加成的较差的非对映选择性。此处描述的研究使用了Nozaki-Hiyama-Kishi反应来关闭中心的7元环，而无需事先安装C11甲基。;第2章：通过反应合成3-carbethoxy-2-取代-3-pyrrolines描述了膦催化的N-甲苯磺酰基-α-氨基烷基亚烷基酯的分子内γ-甲基酚化加成。当前的转化通过膦催化的亚胺与脲基甲酸酯之间的[3 + 2]环化作用，为已知的类似取代的吡咯啉的合成提供了补充。在2位取代基（包括烷基）上的灵活性比以前报道的许多类似取代的吡咯啉合成方法更具优势。通过对烯丙基氨基甲酸酯的新型脱羧重排制备N-甲苯磺酰基-氨基烷基亚烷基酯。第3章：描述了单萜吲哚生物碱（+）-ibophyllidine的对映选择性全合成。所采用的策略基于使用Kwon的L-4-羟基脯氨酸衍生的手性膦催化剂，在关键的不对称膦催化的[3 + 2]环氧化反应中，γ-乙基烯丙酸酯和吲哚-3-醛衍生的N-甲苯磺酰亚胺之间。这一关键的转变构建了立体化学致密的D形环，具有非同寻常的非对映选择性和对映选择性。吡咯啉双键的随后的非对映选择性氢化导致天然产物的完全官能化的全顺式吡咯烷环。吲哚的C3位置的分子内烷基化形成C环，而分子内的氮杂Baylis-Hillman反应被用于锻造E环，从而导致（+）-ibophyllidine的五环骨架。

著录项

  • 作者

    Andrews, Ian Paul.;

  • 作者单位

    University of California, Los Angeles.;

  • 授予单位 University of California, Los Angeles.;
  • 学科 Chemistry General.;Chemistry Organic.;Chemistry Biochemistry.
  • 学位 Ph.D.
  • 年度 2012
  • 页码 252 p.
  • 总页数 252
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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