REACTIVITY AND SELECTIVITY OF REACTIONS IN POLAR MEDIA

这次拨款续期申请的主要重点是进一步审查 一系列有机反应的反应性和选择性 高极性介质，如3.0-5.0M高氯酸锂-二乙醚 应用于具有生物学意义的分子。在.期间 在调查过程中，我们将继续寻找替代品 用于乙醚中的高氯酸锂。此外，我们仍然专注于 比高氯酸盐配位更弱的阴离子。这 提案分为三个部分。 第一节集中研究亲核试剂的反应。 含杂双环[2.2.1]庚烷和杂双环[3.2.1]辛烷 极地媒体。所有拟议的研究都将是根本性的。 为了定义这一过程的范围、限制和机制 潜在的非常有用的新反应。申请总数 环磷酰胺B、乌拉帕利德A、阿普利宁A、吗啡和阿普利定的合成 提出了利福霉素S的C(19)-C(27)脂肪族构筑块。这个 这项赠款申请的第二部分重点是延长Ionic 极性介质中分子内Diels-Alder反应的构建 碳环环系统。将检查底物，其中 构象受限的二烯连接到α上， 亲双烯化合物的β和德尔塔碳原子。适用于 介绍了方酮、麦哲罗酮和戊二烯的合成方法。在……里面 第三部分的赠款申请，我们将研究独特的解决方案 系统(例如Li2B12H12-丙酮、MgB12H12-丙酮)希望找到 在加速的同时改变过渡状态的新机遇 有机反应。此外，我们计划检查硼酸锂和 其中阴离子是手性的磷酸锂有望催化 烯丙基乙酸酯和苄基乙酸酯的单一取代反应 非对映异构体离子对在 由亲核分子发动的攻击。

The major focus of this grant renewal application is to further examine the reactivity and selectivity of a number of organic reactions in highly polar media such as 3.0-5.0 M lithium perchlorate-diethyl ether with applications to molecules of biological interest. During the course of this investigation we will continue to search for substitutes for lithium perchlorate in ether. In addition we remain focused on anions that are more weakly coordinating than perchlorate. This proposal is divided into three parts. The first section concentrates on studying the reaction of nucleophiles with oxabicyclo[2.2.1]heptanes and oxabicyclo [3.2.1]octanes i highly polar media. All the proposed studies will be of a fundamental nature in order to define the scope, limitations, and mechanism of this potentially very useful new reaction. Applications to the total synthesis of epothilone B, ulapualide A, aplyronine A, morphine, and the C(19)-C(27) aliphatic building block of rifamycin S are proposed. The second part of this grant application focuses on extending the ionic intramolecular Diels-Alder reaction in polar media for the construction of carbocyclic ring systems. Substrates will be examined wherein conformationally restricted tethered dienes are attached to the alpha, beta, and delta carbon atoms of the dienophiles. Application to syntheses of quadrone, magellaninone and pentalenene are proposed. In the third part of this grant application we will examine unique solvent systems (e.g. Li2B12H12-acetone, MgB12H12-acetone) in hopes of finding new opportunities for altering transition states while accelerating organic reactions. In addition we plan to examine lithium borates and lithium phosphates wherein the anions are chiral in hopes of catalyzing substitution reactions of allylic and benzylic acetates via single diastereomeric ion pairs which undergo facial discrimination in the attack by a nucleophile.