A new method for enol lactone synthesis by a Michael addition/cyclization sequence
作者:Kennosuke Itoh、Shuji Kanemasa
DOI:10.1016/s0040-4039(03)00147-3
日期:2003.2
Reactions of cyclic 1,3-dicarbonyl compounds with 1-(2-alkenoyl)-4-bromo-3,5-dimethylpyrazoles under the double catalytic activation conditions using both catalytic amounts of Lewis acid and amine catalysts provide a new direct synthetic route to enol lactones. Thus, 1,3-cyclohexanedione is allowed to react with 4-bromo-1-crotonoyl-3,5-dimethylpyrazole, in tetrahydrofuran at room temperature in the
环状1,3-二羰基化合物与1-(2-链烯酰基)-4-溴-3,5-二甲基吡唑在双催化活化条件下使用催化量的路易斯酸和胺催化剂的反应提供了一种新的直接合成途径烯醇内酯。因此,在两种催化量(各为10摩尔%)的高氯酸镍(II)存在下,在室温下使1,3-环己二酮与4-溴-1-巴豆酰基-3,5-二甲基吡唑在四氢呋喃中反应。六水合物和2,2,6,6-四甲基哌啶,以良好的收率得到4,7,7-三甲基-3,4,5,6,7,8-六氢苯并吡喃-2(H),5-二酮。在双催化活化条件以外的反应条件下,该反应不会进行或反应太慢。