Synthesis of Cyclic N-Tosyliminocarbonates by Lewis Acid Catalyzed Allylic Substitution of Trichloroacetimidates
作者:Liene Grigorjeva、Aigars Jirgensons
DOI:10.1002/ejoc.201200378
日期:2012.9
Allylic trichloroacetimidates bearing a δ-N-tosylcarbamoyloxy group were prepared in two steps from the corresponding diols, and their Bronsted and Lewis acid catalyzed cyclization reactions were investigated. It was found that N-tosylcarbamates derived from secondary and tertiary alcohols bearing alkyl substituents undergo a chemoselective allylic alkylation to give N-tosyliminocarbonates in good
由相应的二醇分两步制备带有 δ-N-甲苯磺酰基氨基甲酰氧基的烯丙基三氯乙酰亚胺酯,并研究了它们的布朗斯台德酸和路易斯酸催化的环化反应。发现衍生自带有烷基取代基的仲醇和叔醇的 N-甲苯磺酰氨基甲酸酯经历化学选择性烯丙基烷基化,以良好的分离产率得到 N-甲苯磺酰氨基碳酸酯。反过来,芳基取代的底物往往会通过提取氨基甲酸酯官能团来产生恶唑啉。衍生自仲醇的 N-甲苯磺酰基氨基甲酸酯的环化优先得到反式亚氨基碳酸酯。然而,反式选择性变化并取决于取代模式、底物的配置和催化剂。通过使用 TMSOTf 作为催化剂,可以从(E)底物实现高反式选择性。亚氨基碳酸酯的合成效用通过将它们转化为 1,2-二醇和环状碳酸酯以及通过卤化物离子诱导的重排转化为 N-甲苯磺唑啉酮来证明。