Boronic Acids for Transition Metal Free Organic Synthesis

合成有机(含碳)分子的新化学反应的发展在发现新的药物和功能材料(如液晶、发光二极管)方面发挥着核心作用。在过去的几十年里，涉及含有过渡金属的物种的此类反应大幅增加。虽然这些金属非常有用，但它们也有各种缺点，包括稀有性(以及相关的高成本)和毒性。近年来，无金属方法在有机合成中受到了极大的关注，这些方法在效率方面与许多基于金属的方法相竞争，但没有相关的缺点。某些含硼的有机化合物(硼酸及其衍生物)通常用作金属催化反应的试剂，但很少用作催化剂本身，尽管它们有许多有用的性质。这些特性包括相对较低的毒性、对空气和湿气的稳定性、低成本以及允许它们以独特的方式与某些底物(Lewis碱)反应的Lewis酸性。我们利用这些性质中的一部分来促进所谓的Friedel-Craft反应，这是构建有用的分子结构的重要过程。拟议的研究涉及进一步开发在这些和其他重要过程中用作催化剂的硼酸的独特性质，包括环加成(环形成)和重排反应。硼酸作为药物和材料化学试剂的普遍使用也促使我们开发新的制备方法。我们还将开发以硼酸衍生物为原料的新反应，以此为原料进行无金属反应。其中几个反应产生的产物中，硼基团保持不变，与现有方法协同作用，进一步转化了该基团。这些新方法将使用其他方法难以或不可能制备的新的、有用的分子的制备成为可能。

The development of new chemical reactions for the synthesis of organic (carbon-containing) molecules plays a central role in the discovery of novel pharmaceuticals and functional materials (e.g. liquid crystals, light-emitting diodes). Past decades have seen a huge increase in such reactions involving transition-metal containing species. Although very useful, these metals have various drawbacks, including rarity (and associated high cost) and toxicity. Recently, significant attention has been paid to metal-free methods in organic synthesis, which now compete favourably in terms of efficiency with many metal-based methods without the associated disadvantages. Certain organic compounds of boron (boronic acids and their derivatives) are used commonly as reagents in metal catalysed reactions, but rarely as catalysts themselves, despite their many useful properties. These include relatively low toxicity, stability to air and moisture, low cost and their Lewis acidic nature which allows them to react in unique ways with certain substrates (Lewis bases). We have employed some of these properties to promote the so-called Friedel-Crafts reaction, which is an important process for the construction of useful molecular structures. The proposed research involves further exploitation of the unique properties of boronic acids for use as catalysts in these and other important processes, including cycloaddition (ring-forming) and rearrangement reactions. The common use of boronic acids as reagents for medicinal and materials chemistry has also prompted us to develop new methods for their preparation. We will also develop new reactions involving boronic acid derivatives as starting materials in metal free reactions. Several of these reactions lead to products where the boron group remains intact, providing synergy with existing methods for further transformation of this group. These new methods will enable the preparation of new, useful molecules that would be difficult or impossible to prepare by other means.**