Highly trans-selective synthesis of β-lactams by tandem Lewis base-catalyzed Mannich-type addition and cyclization was established; that is, reaction of benzylideneanilines and trimethylsilyl enolates derived from S-ethyl thioates proceeded smoothly to afford the corresponding β-lactams in good to high yields with high trans-selectivity by using Lewis base catalyst such as lithium phenoxide or tetrabutyl ammonium phenoxide in DMF at −45 °C or THF at −78 °C, respectively.
通过串联路易斯碱催化的曼尼希式加成和环化,高反选择性地合成了 β-内酰胺;即分别在 -45 °C 的
DMF 或 -78 °C 的 THF 中,使用路易斯碱催化剂(如苯氧
锂或四丁基苯氧
铵),使苯并
芘和由 S-乙基
硫代酸酯衍生的三甲基
硅烯醇酯反应顺利进行,以良好至高产率和高反式选择性得到相应的 β-内酰胺。