一、雙功能硫脲催化亞烷基米氏酸與亞胺葉立德進行 (3+2) 環加成、內酯化不對稱合成𠳭酮[4,3-b]吡咯啶二、膦催化誘導化學選擇性還原/亞硝酸脫去/威悌反應合成3-烯基苯并呋喃

Abstract

一、以亞烷基米氏酸與亞胺葉立德在有機催化下進行不對稱合成，經由 (3+2) 環加成與內酯化，脫去了丙酮及二氧化碳，建構chromeno[4,3-b]pyrrolidine骨架。而金雞納鹼衍生的硫脲催化劑僅需1 mol%，即可在短時間得到高產率，並且擁有優秀的鏡像及非鏡像選擇性，而副產物丙酮與二氧化碳對環境友善也容易去除。二、以方便製備的硝苯乙烯衍生物進行氧-醯化反應，並在催化膦的系統下進行3-烯基苯并呋喃的合成。在催化膦的系統中，還原劑苯基矽烷會還原氧化膦，並依序進行膦-麥可加成、亞硝酸脫去與威悌反應，在一鍋化且非金屬的條件下，建構3-烯基苯并呋喃骨架。在此，硝基不僅作為好的拉電子基來幫助膦偶極體產生，建構苯并呋喃，也在過程中扮演好的離去基形成碳-碳雙鍵，提供一種新的方式建構3-烯基苯并呋喃的骨架。1. A highly efficient asymmetric synthesis of chromeno[4,3-b]pyrrolidine of alkylidene meldrum's acid and ortho-hydroxyl azomethine ylides was reported in this thesis. The reactions were catalyzed by 1 mol% cinchona alkaloid derived thiourea catalyst via (3+2) cycloaddition, lactonization and elimination of acetone and carbon dioxide. In the short time, the high yields and excellent enantio- and diastereoselectivities were got. The green side products acetone and carbon dioxide were easily to remove. 2. An efficient protocol for the construction of functionalized 3-alkenyl benzofuran from readily available nitrostyrene derivative by using catalytic amount of phosphine without metal. This one-pot reaction initialed by the phospha-Michael addition of phosphine to O-acylated nitrostyrene, in which phosphine was in-situ-generated from the chemoselective reduction of phosphine oxide with phenylsilane, nitrous acid elimination and Wittig reaction. The nitro group functions not only as an electron-withdrawing group to activate effective construction of benzofuran, but also it plays as a leaving group to provide a carbon-carbon double bond.