School of Science, Henan Agricultural University, Zhengzhou 450002, China..
Molecules. 2013 Sep 26;18(10):11964-77. doi: 10.3390/molecules181011964.
An efficient synthesis of 2-hydroxy-2-(trifluoromethyl)-2H-chromene-3-carboxylates was carried out under solvent-free conditions in an oven or microwave oven via the Knoevenagel condensation of salicylaldehydes with ethyl trifluoroacetoacetate followed by intramolecular cyclization in the presence of silica-immobilized L-proline. The structures of the title compounds were characterized by IR, ¹H-NMR, ¹³C-NMR, HRMS and X-ray single crystal diffraction. The improved method described herein is economical, easily-operated and environmentally friendly. Furthermore, the catalyst can be recovered conveniently and reused without obvious loss of activity.
在无溶剂条件下，通过在烤箱或微波中，用苯甲醛与三氟乙酰乙酸乙酯进行 Knoevenagel 缩合，然后在硅胶固载 L-脯氨酸存在下进行分子内环化，高效合成了 2-羟基-2-(三氟甲基)-2H-色烯-3-羧酸酯。标题化合物的结构通过 IR、1H-NMR、13C-NMR、HRMS 和 X 射线单晶衍射进行了表征。本文所描述的改进方法经济、操作简单、环境友好。此外，催化剂可以方便地回收和重复使用，活性没有明显损失。
