Chemoselective Amide Formation Using <i>O</i>-(4-Nitrophenyl)hydroxylamines and Pyruvic Acid Derivatives
作者:Sonali Kumar、Rashi Sharma、Megan Garcia、Joseph Kamel、Caroline McCarthy、Aaron Muth、Otto Phanstiel
DOI:10.1021/jo302175g
日期:2012.12.7
the oxime functional group played a key role in both the ease by which the oxime could be reduced and the subsequent reactivity of the respective hydroxylamine. Reaction of the respective hydroxylamines with pyruvic acid derivatives generated the desired amides in good yields. A comparison of phenethylamine systems bearing different leaving groups revealed significant differences in the rates of these
使用脉冲添加过量的NaBH 3由它们各自的肟合成了一系列O-(4-硝基苯基)羟胺pH值为3时CN的产率为65–75%。肟官能团附近的立体位阻在减少肟的难易程度和相应羟胺的后续反应性中都起着关键作用。各个羟胺与丙酮酸衍生物的反应以良好的产率产生了所需的酰胺。带有不同离去基团的苯乙胺体系的比较表明,这些体系的速率存在显着差异,这表明N-OR取代基的离去基团能力在确定其与丙酮酸的反应性方面起着重要作用。使用1当量的N-苯乙基-O进行竞争实验(在68%DMSO /磷酸盐缓冲盐水中)在其他亲核试剂如甘氨酸,半胱氨酸,苯酚,己酸和赖氨酸的存在下,-(4-硝基苯基)羟胺和2当量的丙酮酸证明该反应中存在明显的化学选择性。结果表明该化学选择性反应可以在过量的α-氨基酸,酚,酸,硫醇和胺的存在下发生。