修飾噁唑硼烷之中、微孔洞材料應用於酮類不對稱催化還原反應

Abstract

單一光學活性化合物在治療疾病上是很重要的，所以催化合成純旋光性的藥物在目前研究是重要且很熱門的。再者，現今環保意識高漲，催化劑的回收再利用變成一個很重要的課題。 本論文的研究目的即是要開發具有催化不對稱合成的中孔洞材料，以SBA-15或矽膠作為固相載體，希冀提升產物的光學選擇性，並能在反應結束後直接離心收回催化劑。在SBA-15孔洞中生成噁唑硼烷催化劑，利用孔洞環境來提升催化劑選擇性及延長催化劑壽命。另一方面利用分子拓印技術拓印出反應中間體並將其修飾於矽奈米粒子上，利用此空間所具有的互補作用力來誘導CBS還原 (Corey- Bakshi-Shibata reduction) 反應的進行，此研究將使用穿透式電子顯微鏡，比表面積分析儀， X-光粉末繞射儀與元素分析儀來測定材料性質，並利用高效能液相層析儀分析產物光學純度。

Pure optical compounds are very important in treating diseases, and thus development of effective asymmetric syntheses to prepare enantiomerically pure pharmophores has attracted a lot of attentions. Moreover, environmental consciousness runs high nowadays. Re- covery of catalysts used in the reactions has become a very important research topic. The objective of my thesis research is to develop oxazaborolidine- modified micro- and meso-porous materials such as SBA-15 or silica gels. It is hoped that the resulting materials can be used to catalyze asymmetric reduction of ketones effectively and recycled after the complete reactions by simple centrifugation. Two different approaches were employed to graft the oxazaborolidine to the solid supports. In the case of SBA-15, oxazaborolidine catalyst precursor was grafting directly to the inner surface of the pores in the hope of making use of confined space to improve the catalyst enantioselectivity and extend the lifespan of catalyst. The second approach is to fabricate the transition state analog imprinted silanes directly on the silica nanoparticle to facilitate CBS (Corey- Bakshi-Shibata) reduction via spatial and functional groups complement- tary interactions. Transmission electron microscope, surface area and porosity analyzer, X-ray powder diffraction, and element analysis were used to characterize the resulting micro- and meso-porous materials. Enantioselectivity of the reduction reactions was analyzed by high performance liquid chromatography to assess the performance of the fabricated materials.