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Approach to the total synthesis of massileunicellins.

机译：Massileunicellins的全合成方法。

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摘要

The massileunicellins are a family of highly oxidized eunicellin diterpenes that possess a densely functionalized isobenzofuran core in which all eight of the ring carbons are stereocenters. In addition, they possess a tertiary alcohol stereocenter at C3 adjacent to the isobenzofuran.;An oxidative rearrangement-epoxidation reaction of the isobenzofuran intermediate under the conditions of PCC/NaOAc or Collins' reagent produced epoxy ketone 17.3 with the desired C11 oxygen stereochemistry. Opening the epoxide and forming the enol silyl ether 23.2 followed by Rubottom oxidation gave a dihydroxyl ketone 23.3 with the desired alpha-C13 hydroxyl group. A directed reduction of C12 carbonyl group of diol 23.3 afforded C12 hydroxyl group of triol 23.4 with desired stereochemistry. Acylation of triol 23.4 followed by oxidative cleavage gave ketone 24.2. Directed reduction with Crabtree's catalyst of ketone 24.2 afforded desired C10 beta-hydrogen. Chelation controlled carbonyl addition of ketone 27.1 assisted with Ti(OiPr)4 successfully gave alcohol 27.2 as a single diastereomer at C3.;In this thesis, a stereoselective approach to the fully functionalized isobenzofuran core structure is described. (S)-(+)-Carvone was chosen as the starting material for the total synthesis of massileunicellins. Reduction of the less hindered alkene of (S)-(+)-carvone using Willkinson's catalyst yielded dihydrocarvone. Aldol reaction of dihydrocarvone and methacrolein followed by etherification under optimized condition afforded glycolate intermediate 8.2. Cycloaldol reaction of glycolate upon treatment with KHMDS at -78°C gave isobenzofuran intermediate 15.2 as a single diastereomer.
机译：Massileunicellins是一类高度氧化的eunicellin二萜类，具有密集的功能化异苯并呋喃核心，其中所有八个环碳均为立体中心。此外，它们在与异苯并呋喃相邻的C3处具有叔醇立体中心。在PCC / NaOAc或Collins试剂的条件下，异苯并呋喃中间体的氧化重排-环氧化反应产生具有所需C11氧立体化学的环氧酮17.3。打开环氧化物并形成烯醇甲硅烷基醚23.2，随后进行Rubottom氧化，得到具有所需α-C13羟基的二羟基酮23.3。二醇23.3的C12羰基的直接还原得到具有所需立体化学的三醇23.4的C12羟基。将三醇23.4酰化，然后氧化裂解，得到酮24.2。用Crabtree的酮24.2催化剂直接还原得到所需的C10β-氢。配合Ti（OiPr）4辅助螯合控制的酮27.1羰基加成反应，在C3上成功制得醇27.2为单一非对映异构体。本论文描述了对全功能化异苯并呋喃核结构的立体选择方法。选择（S）-（+）-香芹酮作为Massileunicellins的全合成原料。使用威尔金森氏催化剂还原受阻较少的（S）-（+）-香芹酮链烯，可制得二氢香芹酮。二氢香芹酮和甲基丙烯醛的醛醇缩合反应，然后在最佳条件下醚化，得到乙醇酸酯中间体8.2。在-78℃下用KHMDS处理时，乙醇酸酯的羟醛的环醛醇反应产生异苯并呋喃中间体15.2，为单一非对映异构体。

著录项

  • 作者

    Mou, Zonghong.;

  • 作者单位

    University of Arkansas.;

  • 授予单位 University of Arkansas.;
  • 学科 Chemistry Organic.
  • 学位 M.S.
  • 年度 2009
  • 页码 40 p.
  • 总页数 40
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

  • 入库时间 2022-08-17 11:38:24

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