A range of Grignard and organolithium reagents added to the negatively charged sulfur atom of the inner salt 1, despite the presence of the positively charged carbenium carbon, to give enethiolates 4, which were methylated by MeI to give dithioacetals 3 as the final product in excellent yields. A mechanism involving a single-electron-transfer process from nucleophiles to 1 is presented for this thiophilic addition.
一系列
格氏试剂和
有机锂试剂加到内盐 1 带负电的
硫原子上(尽管存在带正电的
硒碳),生成烯
硫醇酯 4,这些烯
硫醇酯在 MeI 的作用下发生甲基化,最终生成
二硫代乙酸酯 3,收率极高。这一亲
硫加成反应的机理涉及从亲核物到 1 的单电子转移过程。