Acylative kinetic resolution of racemic methyl-substituted cyclic alkylamines with 2,5-dioxopyrrolidin-1-yl (<i>R</i>)-2-phenoxypropanoate
作者:Dmitry A. Gruzdev、Sergey A. Vakarov、Marina A. Korolyova、Ekaterina V. Bartashevich、Andrey A. Tumashov、Evgeny N. Chulakov、Marina A. Ezhikova、Mikhail I. Kodess、Galina L. Levit、Victor P. Krasnov
DOI:10.1039/d1ob02099d
日期:——
methyl-substituted cyclic alkylamines with active esters of 2-phenoxypropanoic acid was studied in detail. The ester of (R)-2-phenoxypropanoic acid and N-hydroxysuccinimide was found to be the most selective agent. The highest stereoselectivity was observed in the kinetic resolution of racemic 2-methylpiperidine in toluene at −40 °C (selectivity factor s = 73) with the predominant formation of (R,R)-amide
详细研究了一些外消旋甲基取代的环状烷基胺与2-苯氧基丙酸的活性酯的非对映选择性酰化反应。( R )-2-苯氧基丙酸和N-羟基琥珀酰亚胺的酯被发现是最具选择性的试剂。在 -40 °C 下,在甲苯中的外消旋 2-甲基哌啶的动力学拆分中观察到最高的立体选择性(选择性因子s = 73),主要形成 ( R , R )-酰胺 (93.7% de)。为了解释观察到的立体选择性,对标题酰化剂与 2-甲基哌啶和 2-甲基吡咯烷反应中的过渡态进行了 DFT 建模。计算值与实验数据吻合良好。已经证明酰化通过协同机制进行,其中胺的添加与羟基琥珀酰亚胺片段的消除同时发生。与 ( R , S )-酰胺的形成相比,( R , R )-酰胺形成的高立体选择性很大程度上是由过渡态中较低的空间位阻确保的。