MANGANESE (III) BASED OXIDATIVE FREE RADICAL CYCLIZATION

氧化自由基环化，其中最初的 自由基被氧化生成和/或环状自由基被氧化成 终止反应，具有相当大的合成潜力，因为 可以用更简单的前驱体制备高度功能化的产品 与标准的锡氢化物还原自由基环化反应相比。这个 本研究的目的是发展氧化自由基环化反应 成为一种可靠和通用的方法来合成高度 官能化的环和多环化合物。这项建议包括 几个相互关联的研究开发新的合成方法 氧化自由基环化反应机理的研究 使用锰(III)、铜(II)或Ce(IV)作为氧化剂，以及几种天然的 旨在开发和开发氧化自由基的产品合成 骑自行车。 在方法开发方面，我们计划研究：(1) 除炔烃外，溶剂效应，(2)使用卤代烯进行控制 环化的区域化学，(3)新的取代模式，(4) 通过添加腈进行捕获，(5)通过添加醛进行捕获， (6)氧化、环化、氧化、环化；(7)氧化 环化后分子间捕获，(8)氧化， 环化、烯丙化、氧化和环化，(9)共轭化合物的使用 β-酮酸酯，(10)不对称自由基亚硫醚的使用 环化，(11)自由基环化可逆性的探针， (12)不饱和硅烯醇醚的氧化环化，(13) 不饱和硅氧基环丙烷的氧化环化，和(14) 用羧酸铜将其他自由基转化为烯烃。在 我们计划进行的全合成领域：(1) 呋喃唑酮，(2)赤霉酸的关键三环中间体 合成，(3)甜菊醇，(4)树脂，(5)燕麦内酯，和(6)模型 阿克拉维酮合成。 这项工作的重点是开发新的合成材料 方法学将广泛适用于合成一个广泛的 多种生物活性化合物。到目前为止获得的结果表明 氧化自由基环化将是一种重要的新方法 适用于制备各种高度功能化的 循环和多循环目标。这些方法和合成项目有 旨在提高人们对 自由基化学与氧化新应用 自由基环化反应。

Oxidative free-radical cyclization, in which the initial radical is generated oxidatively and/or the cyclic radical is oxidized to terminate the reaction, has considerable synthetic potential since more highly functionalized products can be prepared from simpler precursors than with the standard tin hydride reductive radical cyclizations. The goal of this research is to develop oxidative free-radical cyclization into a reliable and versatile method for the synthesis of highly functionalized cyclic and polycyclic compounds. This proposal consists of several interrelated studies developing new synthetic methods based on, and examining the mechanism of, oxidative free-radical cyclization using Mn(III), Cu(II) or Ce(IV) as the oxidant, and several natural product syntheses designed to exploit and develop oxidative free-radical cyclization. In the area of methods development we plan to examine: (1) addition to alkynes, solvent effects, (2) use of haloalkenes to control the regiochemistry of the cyclization, (3) new substitution patterns, (4) trapping by addition to nitriles, (5) trapping by addition to aldehydes, (6) oxidation, cyclization, oxidation, cyclization, (7) oxidative cyclization followed by intermolecular trapping, (8) oxidation, cyclization, allylation, oxidation and cyclization, (9) use of conjugated beta-keto esters, (10) use of sulfoxides for asymmetric free-radical cyclization, (11) probes for the reversibility of radical cyclization, (12) oxidative cyclization of unsaturated silyl enol ethers, (13) oxidative cyclization of unsaturated silyloxycyclopropanes, and (14) conversion of other radicals to alkenes with copper carboxylates. In the area of total synthesis we plan to carry out syntheses of: (1) velloziolone, (2) a key tricyclic intermediate for gibberellic acid synthesis, (3) steviol, (4) iresin, (5) avenaciolide, and (6) models for aklavinone synthesis. The focus of this work is the development of new synthetic methodology that will be broadly applicable in the synthesis of a wide variety biologically active compounds. Results obtained to date suggest that oxidative free-radical cyclization will be an important new method applicable to the preparation of a wide variety of highly functionalized cyclic and polycyclic targets. The methods and syntheses projects have been designed to lead to increased mechanistic understanding of free-radical chemistry and develop new applications of oxidative free-radical cyclizations.