合成掌性硼陽離子衍生物

Abstract

三配位硼化合物具有三角平面幾何形狀，硼中心的空p軌道，使其具有路易斯酸的性質。利用在分子中引入正電荷，進一步增加其酸性，形成硼陽離子。由於酸性的增加，硼陽離子對化學計量的轉化和催化作用引起了越來越多科學家的注意。近年來，分子掌性特質在醫學方面不斷被廣泛研究，硼催化劑在不對稱合成的應用也持續被開發中。本研究成功合成帶有噁唑啉衍生配體的手性三配位中性硼化合物及其相應的陽離子化合物。這些化合物已通過1H，11B，13C，2D（HMBC，HSQC，COSY）NMR光譜鑑定，並藉由X射線晶體學確認結構。除此之外，利用Gutmann-Beckett方法測定硼化合物的路易斯酸性，並探討合成的掌性硼化合物在不對稱反應中的應用。

Tricoordinate boron compounds possess a trigonal planer geometry with a vacant p orbital allowing it to behave as a Lewis acid. In the case of boron cations, the Lewis acidity of boron center will be further increased by introducing a positive charge to the molecule. Thus, boron cation has drawn an increase interest in stoichiometric and catalytic transformations. Over the years, the importance of chirality of a molecule on its medicinal applications had been extensively investigated. The application of boron catalysts in asymmetric synthesis has also been explored. In this research, chiral three-coordinate neutral and cationic boron compounds bearing an oxazoline-derived ligand were prepared. These compounds have been fully characterized by 1H, 11B, 13C, and 2D (HMBC, HSQC, COSY) NMR spectroscopy, and X-ray crystallography. The Lewis acidity of the boron compounds was also determined by Gutmann-Beckett method. The application of the synthesized chiral boron compounds in asymmetric synthesis will also be discussed.