Efficient Access to Cyclic Ureas via Pd-Catalyzed Cyclization
摘要:
An efficient regioselective method for the preparation of structurally diverse imidazopyridinones and benzoimidazolones starting from readily available and economical starting materials is described. High-yielding reductive alkylation of electron-deficient o-haloarylamines followed by treatment with inexpensive N-chlorosulfonyl isocyanate afforded primary ureas in good overall yields. A Pd-catalyzed urea cyclization reaction furnished imidazopyridinones and benzoimidazolones in excellent yields. Overall, the developed chemistry provides rapid access to pharmaceutically important heterocyclic compounds with high efficiency.
Radicals derived from N-(alpha-xanthyl)acetanilides or N-(alpha-xanthyl)acetylaminopyridines possessing a substituent next to the nitrogen undergo a hitherto undocumented Smiles rearrangement proceeding through a four-membered ring. It was also found that under certain conditions the amidyl radical produced by cleavage of the four-membered ring intermediate can undergo fragmentation to give an isocyanate. Such fragmentations are unprecedented at temperatures corresponding to refluxing benzene or chlorobenzene.
Synthesis of Disubstituted Imidazo[4,5-<i>b</i>]pyridin-2-ones
作者:Jeffrey T. Kuethe、Audrey Wong、Ian W. Davies
DOI:10.1021/jo048887v
日期:2004.10.1
palladium-catalyzed amination of 2-chloro-3-iodopyridine followed by a subsequent palladium-catalyzed amination leads to 2,3-diaminopyridines. Treatment with triphosgene affords highly functionalized unsymmetrical imidazo[4,5-b]pyridin-2-ones in just three synthetic steps. A two-step synthesis of pseudosymmetrically disubstituted imidazo[4,5-b]pyridin-2-ones, 1,4-disubstituted pyrido[2,3-b]pyrazinediones
区域选择性钯催化的2-氯-3-碘吡啶的胺化,然后是随后钯催化的胺化,生成2,3-二氨基吡啶。用三光气处理仅需三个合成步骤即可得到高度官能化的不对称咪唑并[4,5 - b ]吡啶-2-酮。pseudosymmetrically二取代的咪唑并[4,5的两步合成b ]吡啶-2-酮,1,4-二取代吡啶并[2,3- b ] pyrazinediones,和1,3-二取代的噻二唑并[3,4- b还描述了吡啶-2-酮。
Synthesis of Imidazo[4,5-<i>b</i>]pyridines and Imidazo[4,5-<i>b</i>]pyrazines by Palladium Catalyzed Amidation of 2-Chloro-3-amino-heterocycles
作者:Adam J. Rosenberg、Jinbo Zhao、Daniel A. Clark
DOI:10.1021/ol300359s
日期:2012.4.6
A facile synthesis of imidazo[4,5-b]pyridines and -pyrazines is described using a Pd-catalyzed amide coupling reaction. This reaction provides quick access to products with substitution at N1 and C2. A model system relevant to the natural product pentosidine has been demonstrated, as well as the total synthesis of the mutagen 1-Me-5-PhIP.
使用Pd催化的酰胺偶联反应描述了咪唑并[4,5- b ]吡啶和-吡嗪的简便合成方法。通过该反应,可以快速获得在N1和C2处被取代的产物。已经证明了与天然产物戊糖苷有关的模型系统,以及诱变剂1-Me-5-PhIP的全合成。
Efficient Access to Azaindoles and Indoles
作者:Mark McLaughlin、Michael Palucki、Ian W. Davies
DOI:10.1021/ol061232r
日期:2006.7.1
An expedient, catalytic method for the synthesis of diverse azaindoles and indoles, starting from readily available and inexpensive starting materials, is described. Conditions were developed for effective reductive alkylation of electron-deficient o-chloroarylamines, substrates previously viewed as poor partners in this reaction. The derived N-alkylated o-chloroarylamines were elaborated to N-alkylazaindoles and N-alkylindoles via a novel one-pot process comprising copper-free Sonogashira alkynylation and a base-mediated indolization reaction.
An Improved Synthesis of Imidazo[4,5-<i>b</i>]pyridines and Imidazo[4,5-<i>b</i>]pyrazines by Palladium Catalyzed Amidation using Xantphos in a 1,4-Dioxane:<i>tert</i>-Amyl Alcohol Solvent System
作者:Adam J. Rosenberg、Ijaz Ahmed、Robert J. Wilson、Theresa M. Williams、Lauren Kaminsky、Daniel A. Clark
DOI:10.1002/adsc.201400465
日期:2014.11.3
AbstractHerein an improved protocol for the synthesis of imidazo[4,5‐b]pyridines and imidazo[4,5‐b]pyrazines using a palladium‐catalyzed amidation that utilizes Xantphos as an ancillary phosphine ligand is reported. The use of a binary solvent system comprised of 1,4‐dioxane and tert‐amyl alcohol was crucial in eliminating unwanted by‐products.magnified image