可回收催化劑之開發與評估及其在醯胺鍵生成之應用

Abstract

醯胺類化合物廣泛存在於天然物與合成藥物中，是故醯胺鍵的合成在有機化學及生物化學中為重要的課題之一。然而，目前常用於合成醯胺鍵的方法仍然具有幾個缺點，例如須使用昂貴且有毒的試劑以及反應過後所殘留的大量副產物。因此，近年來對於開發合成醯胺鍵的新方法已受到許多有機化學家的關注，以溫和的反應條件以及高效率的催化效果為目標，開發出新一代符合綠色化學的合成方法。 在此研究中，我們設計並合成能夠催化羧基和胺基之間並形成醯胺鍵的含氟長鏈硼酸催化劑。相較於傳統合成方法，此類硼酸催化劑具有高穩定性、高催化效率、溫和反應條件等特點，且修飾上的氟長鏈使此催化劑得以利用氟化學方法輕易的將催化劑回收並保有高回收率(95%)。本論文將會仔細探討具不同取代基的硼酸催化劑之合成及結構鑑定，以及將所開發的催化劑進行一系列的醯胺化實驗，甚至是分子內的合環反應而形成內醯胺化合物，並檢視其催化效果。最後我們將探討反應機理以及不同取代基之間對於醯胺化產率之影響。

Amide bond formation has been one of the most important reactions in organic synthesis. From natural biomolecules to synthetic products, the importance and utility of amide bonds have received tremendous attention for centuries. However, current synthetic strategies for amide bond formations still suffer from several drawbacks including the use of stoichiometric amounts of expensive coupling reagents as well as massive production of byproducts and wastes. Thus, there is a need for development of mild, simple and waste-free synthetic methods for amide bond formation. In this research, several phenylboronic acids capable of catalyzing direct amidation condensation between a carboxylic acid and an amine were designed and synthesized. These catalysts are found to be stable and functional under practical conditions, and can be recycled with more than 90% recovery. A series of amidation screening experiments were performed to assess the catalytic performance of these catalysts using a variety of carboxylic acid and amine substrates. Therefore, we believe that direct amidation reaction catalyzed by a recyclable boronic acid would be a promising synthetic method in the near future due to its efficiency, convenience, and most importantly, environmental friendly processes.