Pyridinyl Amide Ion Pairs as Lewis Base Organocatalysts
作者:Julian Helberg、Torsten Ampßler、Hendrik Zipse
DOI:10.1021/acs.joc.0c00114
日期:2020.4.17
Pyridinyl amide ion pairs carrying various electron-withdrawing substituents were synthesized with selected ammonium or phosphonium counterions. Compared to neutral pyridine-based organocatalysts, these new ion pair Lewis bases display superior catalytic reactivity in the reaction of isocyanates with alcohols and the aza-Morita–Baylis–Hillman reaction of hindered electrophiles. The high catalytic activity
Electrostatically Enhanced 3- and 4-Pyridyl Borate Salt Nucleophiles and Bases
作者:Stephen H. Dempsey、Alex Lovstedt、Steven R. Kass
DOI:10.1021/acs.joc.3c00523
日期:2023.8.4
A variety of electrostatically enhanced 3- and 4-pyridylborate salt catalysts are reported and show significant improvement over an activated noncharged neutral control compound. Their nucleophilicity in a stoichiometric SN2 reaction and catalytic performance in a urethane synthesis are evaluated along with three methods for rapidly evaluating the basicity of these species. That is, qualitative titrations
据报道,多种静电增强的 3- 和 4-吡啶基硼酸盐催化剂与活化的不带电中性对照化合物相比显示出显着的改进。通过三种快速评估这些物质碱性的方法,评估了它们在化学计量 S N 2 反应中的亲核性和在聚氨酯合成中的催化性能。即,进行了CH 2 Cl 2和CHCl 3中的定性滴定,报道了CCl 4和CDCl 3中的两个单独的溶液态IR研究,并且计算了盐的阴离子组分的质子亲和力。阴离子及其质子化两性离子共轭酸之间的电荷差异以及阴离子的最高占据分子轨道与在两项动力学研究中观察到的一些令人惊讶的反应性发现相关进行了评估。