摘要/Abstract

主要开展了五氟苯酯与烷基叠氮的分子内Schmidt反应研究.以5-叠氮-2-苯基-戊酸五氟苯酯为模板底物，考察了酸促进剂、溶剂以及温度对重排反应的影响，筛选出四氯化钛在回流1，2-二氯乙烷中反应的最优体系.设计并合成了11种5-叠氮-戊酸五氟苯酯，通过在酯基邻位引入芳基、苄基以及烷基等取代基，可提升酯基邻位的迁移动力，使得异氰酸酯阳离子盐为主要重排产物.随后考察该类型Schmidt重排反应的底物普适性，结果表明，当底物中酯基邻位连有富电子芳环或者苄基时，芳基会对重排产物进行加成环合，最终生成内酰胺产物；当底物的酯基邻位连有缺电子芳基或者烷基时，五氟苯酚负离子会对异氰酸酯阳离子亲核进攻，生成氨基甲酸酯产物.五氟苯酚负离子的良好离去性，可启动叠氮基团对酯基的亲核进攻，是Schmidt重排反应得以实现的关键.
关键词: Schmidt反应, 氮杂环, 叠氮化合物, 五氟苯酯, 重排
The intramolecular Schmidt reaction of alkyl azides with pentafluorophenyl esters was investigated. The perfluorophenyl 5-azido-2-phenylpentanoate was employed as the model substrate, and the acid promoter, the solvent and the temperature were scanned. Then the titanium tetrachloride in the refluxing 1,2-dichloroethane was effective for the reaction of perfluorophenyl 5-azido-2-phenylpentanoate. Eleven 5-azido-pentanoates were designed and prepared for exploration, where different aryl, benzyl and alkyl groups were introduced at the α-carbon of perfluorophenyl ester. This type substrate would mainly give isocyanate ion as the primary product from Schmidt rearrangement. Then the scope of substrate was examined, and the experiment results indicated that the substrate with an electron-rich aryl or a benzyl group at the α-carbon of perfluorophenyl ester would afford a lactam via an intramolecular nucleophilic addition of arene to the isocyanate ion, and the substrate with an electron-deficient aryl or an alkyl group at the α-carbon of perfluorophenyl ester would give perfluorophenyl carbamate through an intermolecular capture of isocyanate ion with pentafluorophenol anion. The good leaving apptitude of pentafluorophenol anion should be accounted for inititating the Schmidt reaction, where the nucleophilic attack of azide onto perfluorophenyl ester would proceed very easy.
Key words: Schmidt reaction, N-heterocycle, azides, pentafluorophenyl esters, rearrangement


PDF全文下载地址:

点我下载PDF