以羧酸作为酰化剂的酰化反应及其在有机合成中的应用

Acylation Using Carboxylic Acids as Acylating Agents: Applications in Organic Synthesis

传统的傅-克酰基化反应以酰氯或酸酐作为酰化剂、路易斯酸作为催化剂。大量路易斯酸催化剂及反应产生的氯化氢都需要后处理,并且酰氯对湿度敏感,储存及使用过程中易发生危险。而以三氟乙酸酐作为活化剂、直接以羧酸作为酰化剂的酰化反应不需要事先将羧酸制成酰氯、酸酐或酰胺,且活化剂三氟乙酸酐及副产物三氟乙酸都能很容易地通过蒸馏回收,因此,这类酰化反应能有效解决传统的傅-克酰基化反应所存在的问题。本文综述了近20年来以三氟乙酸酐作为活化剂、直接以羧酸作为酰化剂的酰化反应方法的发展,以及其在功能有机分子、药物分子和天然产物合成中的应用。

The classic Friedel-Crafts acylation uses acid chloride or anhydride as acylating agents,and Lewis acid as catalysts. The large amount of Lewis acid applied and HCl generated in the acylation reaction must be treated. Acid chlorides are sensitive to moisture,and danger might occur during storage and usage. Acylation using carboxylic acids in the presence of trifluoroacetic anhydride as acylating agents does not require conversion of the acylating agents into acid chloride,anhydride or amide. Furthermore,the trifluoroacetic anhydride and trifluoroacetic acid generated can be easily recovered by distillation. Therefore,it can effectively solve the problems associated with the classic Friedel-Crafts acylation. This review summarizes the developments of the acylation process using carboxylic acids in the presence of trifluoroacetic anhydride as acylating agents,and their applications in the syntheses of organic functional molecules,drug molecules and natural products during the last two decades.