在許多天然物和藥物中經常可以發現到五員環的結構，因此 [4+1] 環 化反應引起許多化學家研究的興趣，而如何合成出具有手性的五員環化合 物，更具有挑戰性。本論文第一章節主要目標是利用本實驗室所開發的手性硫化物與溴化芐基形成偶極體，再與起始物進行 [4+1] 環化反應。利用手性硫催化劑進行環化反應時，會因為立體障礙的因素，導致在進行加成時，會選擇立體阻礙較小的位向進行加成，進而得到具有高鏡像超越值的五員環化合物，經過許多條件的篩選與優化，但還是無法得到良好的產率與鏡像選擇性。 本論文第二章節主要目的希望能藉由第二代 Grubbs 催化劑將分別帶有烯基的手性單體與架橋分子共價聯結而形成有機骨架，並將此共價有基骨架應用在不對稱多烯環化反應。由於共價有機骨架不溶於有機溶劑的性質，可以在不對稱多烯環化反應結束後容易回收，同時也希望能達到重複使用的效果。而單體選擇聯?酚並進行修飾，其原因為聯?酚能與四氯化錫結合而形成路易士酸輔助手性布忍斯特酸複合體，可應用於不對稱多烯環化反應。;Five-membered ring is an important structure in natural product and medicinal chemistry. Therefore, [4+1] cyclization has gained much more attention from organic chemists. The main goal of the first chapter of in this thesis is to use the chiral tetrahydrothiophene ligand developed by our lab for the metal-catalyzed asymmetric [4+1] cyclization of propargylic carbamates and sulfur ylides. Finally, we successfully obtained the [4+1] cyclization products with up to 73% yield and 47% ee. The main goal of second chapter is to use the 2nd generation Grubbs catalyst to crosslink the chiral monomer and linker to form a covalent organic framework (COF), which would be then applied to polyene cyclizations. The reason we choose 1,1`-Bi-2-naphtol (BINOL) as the monomer is that it can complex with Tin (IV) chloride for the formation of a Lewis acid-assisted chiral Br?nsted acid system for catalyzing the asymmetric polyene cyclization. Although the COFs we obtained from the olefin cross-metathesiss successfully catalyzed the polyene cyclization, the enantioselectivity is low.
