Stereoselectivity of Additions to N-Methyl Acetonitrilium Fluorosulfonate
摘要:
Alkoxy-N-methyl-acetiminium salts were prepared by addition of CH3OH and C2H5OH to N-methyl acetonitrilium fluorosulfonate at low temperature. Analysis of the (5)J(HH) and (3)J(13)C-H coupling constants in the NMR spectra showed an anti addition with a diastereoselectivity of >9596. Deprotonation of these salts with (Z)-configuration gave the corresponding N-methyl-alkoxyacetimines with very high (E)-configuration. Upon protonation at -78 degrees C, these iminoesters gave the corresponding alkoxy-N-methyl-acetirninium salts with (E)-configuration. Computational analyses of the iminoesters and the corresponding iminium cations including the conformations give insight into the relative stability. Nitrilium salts can be used as reagents, exemplified by some esterifications between simple acids and alcohols.
Use of NOE difference spectra to determine configurations and conformations of imidate esters
作者:David E. Gallis、Delanson R. Crist
DOI:10.1002/mrc.1260250604
日期:1987.6
A new method for determining conformations and configurations of imidate esters was developed based on NOE difference spectra in CDCI3. As a test of the method, methyl N‐methylacetimidate was determined to exist in the E configuration, ap conformation, in agreement with assignments by homoallylic coupling and dipole moment data. Methyl N‐tert‐butylformimidate, for which existing methods were not suitable
基于 CDCI3 中的 NOE 差异光谱,开发了一种确定亚胺酸酯构象和构型的新方法。作为该方法的测试,确定 N-甲基乙酰亚胺酸甲酯以 E 构型、p 构象存在,与同烯丙基耦合和偶极矩数据的分配一致。现有方法不适合的 N-叔丁基甲酰亚胺甲酯也被确定为 E-ap。研究了两种苯甲酸甲酯,即 N-甲基衍生物 2,即 E-ap,和 N-叔丁基衍生物 6,其在室温(Tc = 24°C)下表现出异常容易的 E/Z 异构化。在 ‐58 °C 时,解析光谱显示 E/Z 异构体 6 的比例为 40:60。从 NOE 数据确定 (E)-6 主要作为 ap 构象异构体存在,(Z)-6 作为 sp 构象异构体存在。这些结果,
Stereoselectivity of Additions to <i>N</i>-Methyl Acetonitrilium Fluorosulfonate
作者:Reinhart Keese、François Berdat、Piero Macchi
DOI:10.1021/jo301983s
日期:2013.3.1
Alkoxy-N-methyl-acetiminium salts were prepared by addition of CH3OH and C2H5OH to N-methyl acetonitrilium fluorosulfonate at low temperature. Analysis of the (5)J(HH) and (3)J(13)C-H coupling constants in the NMR spectra showed an anti addition with a diastereoselectivity of >9596. Deprotonation of these salts with (Z)-configuration gave the corresponding N-methyl-alkoxyacetimines with very high (E)-configuration. Upon protonation at -78 degrees C, these iminoesters gave the corresponding alkoxy-N-methyl-acetirninium salts with (E)-configuration. Computational analyses of the iminoesters and the corresponding iminium cations including the conformations give insight into the relative stability. Nitrilium salts can be used as reagents, exemplified by some esterifications between simple acids and alcohols.
Triazapentadienes as acaricides and insecticides
申请人:Pfizer Inc.
公开号:US04011343A1
公开(公告)日:1977-03-08
The preparation of triazapentadienes with acaricidal and insecticidal properties is described.