A Convenient Synthesis of 5-Aryl-6-trifluoromethyl-3,6-dihydro-2<i>H</i>-1,3,4-oxadiazines. A Silica Gel Catalyzed Novel Cyclization Reaction
作者:Yasuhiro Kamitori、Masaru Hojo、Ryöich Masuda、Toshihiko Fujitani、Seiji Ohara、Tetsuya Yokoyama
DOI:10.1055/s-1988-27513
日期:——
Arenecarbaldehyde dimethylhydrazones were successfully acylated by trifluoroacetic anhydride to afford trifluoroacetylated hydrazones 2. Several 5-Aryl-6-trifluoromethyl-3,6-dihydro-2H-1,3,4-oxadiazines 3 were synthesized in good yields by novel cyclization of 2, thus obtained, using silica gel as an effective catalyst. Hydrolytic ring cleavage of 3 afforded α-hydroxyketones 5 bearing the trifluoromethyl group in high yields.
三氟乙酸酐成功地将烯丙基醛二甲基腙酰化,得到三氟乙酰腙 2。通过硅胶作为有效催化剂,对所得的 2 进行新颖的环化反应,合成了几种 5-芳基-6-三氟甲基-3,6-二氢-2H-1,3,4-恶二嗪 3,收率良好。3 的水解环裂解以高收率提供了带有三氟甲基的 α-羟基酮 5。