利用化學選擇性的分子內Wittig反應製備苯并呋喃與呋喃化合物

Abstract

近年來有許多化學選擇性的相關研究，化學家發現這是一個很重要的概念來合成一些複雜的分子結構，像是天然物分子。1954年德國化學家George Wittig發明新的反應，Wittig反應是目前有機合成中有效地應用於合成碳碳雙鍵的方法之一。然而文獻中極少人針對分子內Wittig反應及試劑做進一步的研究。 本論文將探討具有化學選擇性的分子內Wittig反應，針對這個特別的反應我們設計出中間體化合物72’，分子上帶有phosphorus ylide和兩個可反應的酯基團，可經由Michael acceptors、三乙基胺、三丁基磷和醯氯試劑製備而成。接著設計另一個中間體化合物75’，帶有兩個可反應的官能基團酯基與醯胺基。我們預期透過具有化學選擇性的分子內Wittig反應，經過中間體72’及75’來製備苯并呋喃化合物73、呋喃化合物73’和76’以及吲哚化合物76。The investigation of chemoselectivity of reactions always attracts chemists attention because of their importance in the synthesis of complex structures of molecules like natural products. The Wittig reaction is one of the most efficient reactions for carbon-carbon double formation and is widely used in organic synthesis. However,literature survey reveals that for the study of chemoselectivity for known reactions or reagents, few of them are mentioned about intramolecular Wittig reactions. For our interest in chemoselective intramolecular Wittig reactions, we therefore proposed the intermediates 72’ with two possibly reacting ester functions and a phosphorus ylide moiety, which can be prepared from the corresponding Michael acceptors, Et3N, Bu3P, and acid chlorides. The phosphorus ylides 75’ with two possibly reactive functionalties such as an ester and an amide will also be investigated. Our study showed that the preparation of highly functional benzofurans 73, furans 73’ and 76’, indoles 76, and tetrahydrobenzofurans 78 via chemoselective intramolecular Wittig reactions from the corresponding phosphorus ylides 72’ and 75’ can be realized.