Medium- and large-membered cyclic thiolcarbonates containing an (E)- or (Z)-double bond were synthesized by two methods using [3, 3]sigmatropic ring expansion of cyclic thionocarbonates. The [3, 3]sigmatropic ring expansion proceeds exclusively via the transition state bearing the chain tethered in a cis relationship when the cyclic thionocarbonates are 8-membered or smaller. Importantly, the ring size of the cyclic thionocarbonate determines the double bond geometry of the thiolcarbonate.Conversion of the cyclic thiolcarbonates into (E)- or (Z)-allylic sulfides is also described.
通过两种方法,利用环状
硫羰酸酯的[3,3]σ迁移环扩张反应,合成了含有(E)或(Z)双键的中大型环状
硫醇
碳酸酯。当环状
硫羰酸酯为8元或更小时,[3,3]σ迁移环扩张反应仅通过过渡态进行,该过渡态中的链以顺式关系系留。重要的是,环状
硫羰酸酯的环大小决定了
硫醇
碳酸酯的双键几何形状。本文还描述了将环状
硫醇
碳酸酯转化为(E)或(Z)型烯丙基
硫醚的方法。