Asymmetric Lewis Base Catalysis in Main Group Chemistry

主族化学中的不对称路易斯碱催化

• 批准号: 8050550
• 负责人: Scott Eric Denmark
• 金额: $ 28.94万
• 依托单位: UNIVERSITY OF ILLINOIS AT URBANA-CHAMPAIGN
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-03-22 至 2014-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8050550
• 关键词: Acids; Alkenes; Bromine; Carbon; Catalysis; Charge; Chemicals; Chemistry; Chlorine; Constitutional; Coupling; Development; Elements; Esters; Foundations; Frequencies; Heating; Intercept; Investigation; Iodine; Ions; Ketones; Kinetics; Learning; Ligands; Methods; Nitrogen; Oxygen; Process; Reaction; Reagent; Research Proposals; Salts; Scheme; Structure; Sulfur; Transition Elements; Variant; azobis(isobutyronitrile); base; chemical reaction; design; electron density; oxidation; programs; public health relevance

DESCRIPTION (provided by applicant): The primary objectives of this proposal are: (1) to demonstrate the concept of Lewis base activation of Lewis acids (Gutmann electron density polarization) as it applies to electrophilic species in Groups 16 and 17 in the Main Group, (2) to develop catalytic variants of classical main group reactions for which catalysis has yet to be realized, (3) to learn the structure/reactivity correlations and the rules for achieving high catalytic activity (turnover frequencies and turnover numbers) for the target reactions, (4) to design chiral Lewis bases that will impart high stereoselectivity and high chemical conversion for the introduction of new carbon and heteroatom substituted stereocenters, and (5) carry out detailed mechanistic (kinetics, spectroscopic, crystallographic, computational) investigations of the newly-invented catalytic reactions described below. The first major effort will be the development of catalytic, enantioselective variants of the most common reactions of electrophilic Group 16 and 17 reagents. Direct functionalization and cyclofunctionalization of alkenes bearing a tethered nucleophile (oxygen, nitrogen, carbon) is a powerful method for creating stereodefined chains, heterocycles and carbocycles. These reactions are efficiently initiated by electrophilic sulfur(II), chlorine(I), bromine(I), and iodine(I) reagents The design of Lewis bases to catalyze and control the constitutional and enantiofacial selectivity will constitute a major component of this program. The synthetic manipulation of the enantiomerically enriched, sulfur-containing products constitutes the second major activity. In addition to well-known functional manipulations, new, stereocontrolled, constructive replacements of the C-S bond that employ transition metal catalyzed coupling and direct ligand coupling reactions will be developed. A third major effort will be the invention, development, and exploration of a new subclass of Lewis base catalyzed reactions that employs higher oxidation state iodine(III) reagents for carbon-carbon bond formation. Catalysis of the ligand coupling reaction of iodonium salts is unprecedented and will be investigated for the construction of enantiomerically enriched ?-aryl, ?-alkenyl, ?-alkynyl, and also potentially ?-aryl substituted ketones and esters. PUBLIC HEALTH RELEVANCE: This research proposal aims to develop a fundamentally new class of catalytic reactions of the main group elements, sulfur, chlorine, bromine, and iodine in various oxidation states. The conceptual foundation for the ability of Lewis bases to activate the electrophilic character of these elements has almost unlimited potential. Already, catalysis is involved in the processing of nearly a trillion dollars worth of goods produced annually in the US, and our contribution is for chemical reactions for which there is currently no catalytic process.

描述（由申请人提供）：本提案的主要目标是：(1)证明Lewis酸的Lewis碱活化概念（Gutmann电子密度极化），因为它适用于主基团中第16和17基团的亲电物质；(2)开发尚未实现催化的经典主基团反应的催化变体；(3)学习结构/反应性相关性以及实现高催化活性（周转频率和周转数）的规则。(4)设计具有高立体选择性和高化学转化率的手性路易斯碱，以引入新的碳和杂原子取代的立体中心；(5)对下面描述的新发明的催化反应进行详细的机理（动力学、光谱、晶体学、计算）研究。第一个主要的努力将是开发最常见的亲电16和17基团试剂反应的催化、对映选择性变体。带亲核试剂（氧、氮、碳）的烯烃的直接官能化和环官能化是生成立体链、杂环和碳环的有效方法。这些反应是由亲电性的硫（II）、氯(I)、溴(I)和碘(I)试剂有效地引发的。设计路易斯碱来催化和控制结构和对映面选择性将构成本计划的主要组成部分。对映异构富集的含硫产物的合成操作构成了第二大活动。除了众所周知的功能操作，新的，立体控制的，建设性的取代C-S键，利用过渡金属催化偶联和直接配体偶联反应将被开发出来。第三项主要工作将是发明、开发和探索路易斯碱催化反应的新亚类，该反应使用更高氧化态的碘（III）试剂来形成碳-碳键。碘盐配体偶联反应的催化作用是前所未有的，将被研究用于构建对映体富集的？芳基,?烯基,?-炔基，还有可能？-芳基取代酮和酯。