Triple Mode of Alkylation with Ethyl Bromodifluoroacetate:
<i>N</i>
, or
<i>O</i>
‐Difluoromethylation,
<i>N</i>
‐Ethylation and
<i>S</i>
‐(ethoxycarbonyl)difluoromethylation
作者:Arghya Polley、Gurupada Bairy、Pritha Das、Ranjan Jana
DOI:10.1002/adsc.201800824
日期:2018.11.5
chemical reactivity of ethylbromodifluoroacetate. Typically, bromodifluoroacetic acid has been used as a difluorocarbene precursor for difluoromethylation of soft nucleophiles. Here we have disclosed nucleophilicity and base dependent divergent chemical reactivity of ethylbromodifluoroacetate. It furnishes lithium hydroxide and cesium carbonate promoteddifluoromethylation of tosyl‐protected aniline
在这份报告中,我们探索了溴二氟乙酸乙酯的化学反应的三重模式。通常,溴二氟乙酸已被用作软亲核试剂的二氟甲基化的二氟卡宾前体。在这里,我们已经公开了溴二氟乙酸乙酯的亲核性和碱依赖性发散化学反应性。它提供了氢氧化锂和碳酸铯,分别促进了甲苯磺酰基保护的苯胺和缺电子的酚的二氟甲基化作用。有趣的是,将碱从氢氧化锂转变为4- N,N-二甲基氨基吡啶(DMAP)甲苯磺酰基保护的苯胺,得到了相应的N-乙基化产物。而高度亲核的苯硫酚提供了相应的S羰基乙氧基二氟甲基化产物在酯水解之前通过快速的S N 2攻击溴原子而形成。这种机制差异是通过几个控制实验确定的。结果表明,二氟甲基化反应是通过串联原位酯水解/脱羧-脱溴化二氟卡宾的形成并随后被软亲核试剂-NHTs或电子缺陷型酚-OH基团捕获而进行的。在DMAP的存在下,酯的水解受到干扰,相反,在乙基部分的亲核攻击提供了N-乙基化产物。因此,除了开发实用的碱促氮素胺和电
Unusual 1,2-aryl migration in Pd(<scp>ii</scp>)-catalyzed aza-Wacker-type cyclization of 2-alkenylanilines
作者:So Won Youn、So Ra Lee
DOI:10.1039/c5ob00361j
日期:——
Hegedus aza-Wacker indole synthesis, we were intrigued with the fate of the aminopalladation intermediate if syn β-hydrogen is made inaccessible or unavailable. In contrast to our previously reported β-carbon elimination, cyclization of a variety of 2-alkenylaniline substrates under electrophilic palladium conditions unexpectedly afforded C3-substituted indoles. This unusual 1,2-migratory process was
An effective metal-free C-H amination of N-Ts-2-alkenylanilines by using DDQ as an oxidant has been developed to afford a diverse range of substituted indoles. This protocol is operationally simple and robust, obviates the need of expensive transition-metal catalysts, and offers a broad substrate scope. A mechanism involving a radical cation generated by SET and a migratorial process via a phenonium ion intermediate is proposed.