Mechanistic Studies on Nitrosation–Deaminocyclization of Mono-Carbamoylated Vicinal Amino Alcohols and Diols: A New Preparative In Situ Formation of Ethanediazo Hydroxide for the Ethylation of Carboxylates under Mild Conditions
作者:Masumi Suzuki、Takeshi Sugai
DOI:10.1246/bcsj.77.1217
日期:2004.6
underwent smoothly, we found that similar reactions of vicinal diol monocarbamates were very slow. Mechanistic studies by means of time-resolved IR measurements of the former reaction suggested that the initial O-nitrosation was the rate-determining step. Indeed, the introduction of an ethyl group on the nitrogen terminus of diol monocarbamate promoted the desired cyclic carbonate formation. The concomitantly
虽然 N-氨基甲酰氨基醇通过 NO' 活化环化为恶唑烷酮的过程顺利进行,但我们发现邻位二醇单氨基甲酸酯的类似反应非常缓慢。通过前一反应的时间分辨 IR 测量进行的机理研究表明,最初的 O-亚硝化是决定速率的步骤。事实上,在二醇单氨基甲酸酯的氮端引入乙基促进了所需环状碳酸酯的形成。伴随形成的重氮乙烷质子化形式的前体氢氧化乙烷通过用对硝基苯甲酸作为乙酯捕获而得到证实。乙酯的形成以不可逆的方式加速反应。基于对底物和反应条件的阐述,2,3-二甲基-2,