磷酸二氢钾催化Yonemitsu缩合反应合成5-[(3-吲哚基)-芳甲基]-2,2-二甲基-1,3-二噁烷-4,6-二酮衍生物

Potassium Dihydrogen Phosphate Catalyzed Yonemitsu Condensation for Synthesis of 5-[(Indol-3-yl)-arylmethyl]-2,2-dimethyl-1,3-dioxane-4,6-dione Derivatives

以醛、吲哚和麦氏酸为原料,水和乙醇混合液为溶剂,在室温搅拌条件下以磷酸二氢钾为催化剂通过Yonemitsu缩合反应,合成了一系列的5-[（3-吲哚基）-芳甲基]-2,2-二甲基-1,3-二噁烷-4,6-二酮衍生物,产率为48%~98%,并通过X射线单晶衍射仪测定了化合物4o的晶体结构。该方法能够有效的促使反应活性较低的4-甲基苯甲醛和4-甲氧基苯甲醛参与反应,以83%和60%的收率获得相应的目标产物,并具有反应条件温和、催化剂廉价易得、后处理简单、产物易于纯化、产率较高等优点,可用于合成3-取代吲哚类化合物。

A simple and efficient procedure for the preparation of 5-[（indol-3-yl）-arylmethyl]-2,2-dimethyl-1,3-dioxane-4,6-dione derivatives has been developed through the Yonemitsu condensation of indole with Meldrum＇s acid and aldehyde in the mixed solvent of ethanol and water at room temperature using KH2PO4 as an inexpensive, commercially available, and efficient catalyst. The crystal structure of compound 4o was confirmed by X-ray diffraction. This method has the advantages of mild reaction conditions, tolerance to diverse functional groups such as 4-methyl benzaldehyde and 4-methoxy benzaldehyde, and good to excellent yields（48%~98%）. Furthermore, some of the products can be facilely obtained by vacuum filtration without further purification. This strategy provides an alternative approach for easy access to useful synthetic β-indole derivatives.