4-Hydroxyphenacyl Ammonium Salts: A Photoremovable Protecting Group for Amines in Aqueous Solutions
作者:Iwona Bownik、Peter Šebej、Jaromír Literák、Dominik Heger、Zdeněk Šimek、Richard S. Givens、Petr Klán
DOI:10.1021/acs.joc.5b01770
日期:2015.10.2
p-hydroxyphenacyl (pHP) ammonium caged derivatives at 313 nm releases primary and secondary amines or ammonia in nearly quantitative yields via the photo-Favorskii reaction when conducted in acidic or neutral aqueous buffered media. The reaction efficiencies are strongly dependent on the pH with the most efficient and highest yields obtained when the pH of the media maintains the ammonium and p-hydroxyl groups
当在酸性或中性水性缓冲介质中进行光-Favorskii反应时,在313 nm处辐照N-保护的对羟基苯甲酰(pHP)铵笼蔽的衍生物会释放伯胺和仲胺或氨,并通过光-Favorskii反应以接近定量的产率释放出伯胺和仲胺或氨。当介质的pH值保持铵和对羟基为共轭酸时,反应效率主要取决于pH值,从而获得最有效和最高的收率。例如,在酸性pH值从3.9到6.6时,简单仲胺释放的总量子产率为0.5,而在中性pH 7.0时下降为0.1,在pH 8.4时下降为0.01。形态研究提供了酸碱特性,有助于定义反应的范围和限制。当p K a铵盐基团的酚醛基团比酚羟基基团的酚醛基团的胺基团的酚醛基团的酚醛基团的酚醛基团的酚醛基团的酚醛基团的铵盐基团的酚醛酸基团的酚醛基团的铵盐基团低。氨基的离去基团能力。反过来,这降低了发生光-Favorskii重排反应的倾向,并为其他竞争性光还原过程打开了反应途径。