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新药物和功能材料（如液晶、发光二极管）的发现中起着核心作用。在过去的几十年里，这类涉及含过渡金属物种的反应有了巨大的增长。虽然这些金属非常有用，但它们有各种缺点，包括稀有（以及相关的高成本）和毒性。近年来，人们对有机合成中的无金属方法给予了极大的关注，这些方法在效率方面与许多基于金属的方法相竞争，而没有相关的缺点。某些有机硼化合物（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，尽管它们有许多有用的性质。这些特点包括毒性相对较低，对空气和水分的稳定性，成本低，以及它们的刘易斯酸性质，使它们能够以独特的方式与某些底物（刘易斯碱）发生反应。我们已经利用这些性质中的一些来促进所谓的Friedel-Crafts反应，这是构建有用分子结构的一个重要过程。拟议的研究包括进一步开发硼酸的独特性质，用于这些和其他重要过程的催化剂，包括环加成（环形成）和重排反应。硼酸作为药物和物质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作为无金属反应起始原料的新反应。其中一些反应导致产物中硼基团保持完整，与现有方法协同作用，进一步转化该基团。这些新方法将能够制备新的、有用的分子，这些分子用其他方法很难或不可能制备。

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.