α-羰基烯酮环二硫代缩醛化学（Ⅺ）──α-羰基烯酮环二硫代缩醛类化合物与Reformatsky试剂的加成反应初步研究

α-Oxo Ketene Cyclic Dithioacetal Chemistry(Ⅺ)──Preliminary Studies on the Addition Reaction of α-Oxo Ketene Cyclic Dithioacetals with Reformatsky Reagent

报道了标题化合物和Ｒｅｆｏｒｍａｔｓｋｙ试剂［Ｅｔｈｙｌ（ｂｒｏｍｏｚｉｎｃｉｏ）ａｃｅｔａｔｅ］的加成反应。实验表明，该加成反应能否进行和α－羰基烯酮二硫代缩醛类化合物中缩醛基结构密切相关．结合晶体结构数据和构象分析可以推测，当缩醛基的两个烷硫基处在（或近于）同一平面上时，因满足了两个硫原子和Ｒｅｆｏｒｍａｔｓｋｙ试剂形成络合物的电子要求，底物被活化而易发生加成反应；反之，两个烷硫基难于处在同一平面上时，加成反应难以进行。

The addition reactions of the title compounds with the Reformatsky reagent from ethyl bromoacetate were performed and the possible mechanism was discussed.It seems that the decisive factor for this reaction rest on the conformation of the acetal groups in substrate molecules. When the two alkylthio groups are or nearly on the plane,which relay on the structure of the acetal group and the molecule involved, the substrate carbonyl can be activated by the complex formed between substrate and Reformatsky reagent. Otherwise,the addition reaction would be difficult to occur.