Mechanistic and Synthetic Implications of the Diol-Ritter Reaction: Unexpected Yet Reversible Pathways in the Regioselective Synthesis of Vicinal-Aminoalcohols
作者:Mark E. Ondari、Jerzy Klosin、Robert D. J. Froese、William R. Kruper、Jason MacDonald、Dan J. Arriola、Bruce M. Bell、John R. Briggs、William J. Kruper
DOI:10.1021/acs.joc.8b02320
日期:2019.4.19
The Ritter reaction of 1,2-diolmonoesters with nitriles to 1-vic-amido-2-esters proceeds through dioxonium and nitrilium cation intermediates. To provide the basis for the reaction mechanism, novel forms of these cations were isolated, characterized, and studied by spectroscopic methods and single crystal X-ray analysis. Ground and transition state energies were determined both experimentally and theoretically
1,2- diolmonoesters与腈的Ritter反应至1- VIC酰氨基-2-酯前进通过dioxonium和nitrilium阳离子中间体。为提供反应机理的基础,通过光谱方法和单晶X射线分析对这些阳离子的新型形式进行了分离,表征和研究。基态和过渡态能量都是通过实验和理论确定的。总之,这些数据表明,通过迅速形成dioxonium阳离子的反应进行9,接着率确定由乙腈但可逆开环成相应nitrilium阳离子10(计算Δ ģ ⧧在50°C时= 24.7 kcal)。后者的快速,不可逆的水合得到相应的vic-乙酰氨基酯。在乙腈-d 3中向二恶唑鎓阳离子9受控地添加H 2 O导致近似定量的氘代乙酰氨基酯13a的生产。该转化的动力学(9至13a)是双相的,并且慢相归因于乙酰胺通过O-烷基化直接阳离子9攻击或通过可逆醚形成而形成阳离子16。氘标记研究表明O-烷基化阳离子16不会直接异构化为N-烷基