Photoredox Cyanomethylation of Indoles: Catalyst Modification and Mechanism
作者:Connor J. O’Brien、Daniel G. Droege、Alexander Y. Jiu、Shivaani S. Gandhi、Nick A. Paras、Steven H. Olson、Jay Conrad
DOI:10.1021/acs.joc.8b01146
日期:2018.8.17
The versatile nitrile synthon is introduced as a radical generated from bromoacetonitrile, a photocatalyst, and blue LED as a light source. The mechanism of the reaction is explored by determination of the Stern–Volmer quenching constants. By combining photophysical data and mass spectrometry to follow the catalyst decomposition, the catalyst ligands were tuned to enable synthetically useful yields
吲哚在2-或3-位的直接氰甲基化是通过光氧化还原催化实现的。多功能腈合成子是由溴乙腈、光催化剂和蓝色 LED 作为光源产生的自由基。通过测定 Stern-Volmer 猝灭常数来探索该反应的机理。通过结合光物理数据和质谱分析来跟踪催化剂分解,调整催化剂配体以实现自由基偶联产物的合成有用产率。一系列带有烷基、芳基、卤素、酯和醚官能团的吲哚底物参与反应,产生产率 16-90% 的产物。该反应可以快速构建合成上有用的氰基甲基吲哚,否则需要几个合成步骤的产物。
Palladium-Catalyzed Indole and Azaindole Synthesis by Direct Annulation of Electron-Poor<i>o</i>-Chloroanilines and<i>o</i>-Chloroaminopyridines with Aldehydes
for the synthesis of 2-unsubstituted indolesand azaindoles has been developed by the palladium-catalyzed directannulation of electron-poor O-chloro/bromoanilines and O-chloroaminopyridines with aldehydes.Coupled with the previous results of Jia and Zhu, this allows rapidaccess to a variety of 2-unsubstituted indoles and azaindoles startingfrom simple and easily accessible precursors.
Selective Methylation of NH-Containing Heterocycles and Sulfonamides Using N,N-Dimethylformamide Dimethylacetal Based on Calculated pKa Measurements
作者:Gary Fairley、Catherine Hall、Ryan Greenwood
DOI:10.1055/s-0032-1318315
日期:——
The use of N,N-dimethylformamide dimethylacetal (DMF-DMA) as a suitable methylating agent for the methylation of NH-containing groups and heterocycles has been investigated. Use of ReactArray and calculated pK(a) measurements have allowed additional helpful information to be collated to determine optimum reaction conditions for a variety of substrates.
Vinylic MIDA Boronates: New Building Blocks for the Synthesis of Aza-Heterocycles
A two‐step synthesis of structurally diverse pyrrole‐containingbicyclic systems is reported. ortho‐Nitro‐haloarenes coupled with vinylic N‐methyliminodiacetic acid (MIDA) boronates generate ortho‐vinyl‐nitroarenes, which undergo a “metal‐free” nitrene insertion, resulting in a new pyrrole ring. This novel synthetic approach has a wide substrate tolerance and it is applicable in the preparation of