An efficient transformation of ethers to N,N′-disubstituted ureas in a Ritter type reaction
摘要:
A simple, mild, and an alternative protocol for the preparation of N,N'-disubstituted ureas from readily available ethers and cyanamides as starting materials is described. The protocol explores the reactivity of ether in a Ritter type reaction with cyanamide in the presence of BF3 center dot Et2O and resulting in the formation of N,N'-disubstituted urea. Divinyl ether as well as MTBE (methyl tert-butyl ether) can be employed as ether components to afford allyl and tert-butyl ureas respectively. (C) 2012 Elsevier Ltd. All rights reserved.
A Pd/C‐catalyzed domino synthesis of symmetrical and unsymmetrical ureas fromaryl iodides, sodium azide, amines and CHCl3 in water has been developed. This reaction proceeds with sequential carbonylation, Curtius rearrangement and nucleophilic addition. CHCl3 serves as a convenient and safe alternation of CO gas in the presence of KOH. A series of urea derivatives were obtained in moderate to good
A set of Pd‐catalyzed ortho‐directedC—H glycosylation reactions with glycosyl chloride donors using various N‐linked bidentate auxiliaries has been developed for synthesis of C‐aryl glycosides. A broad range of pyranose and furanose moieties can be installed on the ortho position of arylamine, carbazole, indole and benzylamine type substrates in high yield and with high regio‐ and diastereoselectivity
Photocatalyzed synthesis of unsymmetrical ureas via the oxidative decarboxylation of oxamic acids with PANI-g-C3N4-TiO2 composite under visible light
作者:Liang Wang、Hao Wang、Yaoyao Wang、Minggui Shen、Shubai Li
DOI:10.1016/j.tetlet.2020.151962
日期:2020.6
The synthesis of unsymmetrical ureas via the photocatalyzed oxidative decarboxylation of oxamic acids has been developed. The carbamoyl radicals were generated from oxamic acids in the presence of a hypervalent iodine reagent and the PANI(Polyaniline)-g-C3N4-TiO2 composite under visible light irradiation. The radicals were converted in situ into the corresponding isocyanates, which were then trapped
已经开发了通过光催化的草酰胺酸氧化脱羧合成不对称脲的方法。在高价碘试剂和PANI(聚苯胺)-gC 3 N 4 -TiO 2复合材料的存在下,由草酰胺酸在可见光照射下生成氨基甲酰基自由基。自由基被原位转化进入相应的异氰酸酯,然后被胺捕获,以中等至良好的产率得到相应的产物。该方案避免了直接使用对环境不利的异氰酸酯,并且可以耐受一系列底物。而且,光催化剂可以通过简单的过滤而容易地回收,并且可以在仅轻微降低催化活性的情况下重复使用几次。
Ion-exchange resins for solution phase parallel synthesis of chemical libraries
作者:Leah M. Gayo、Mark J. Suto
DOI:10.1016/s0040-4039(96)02362-3
日期:1997.1
Described are various techniques that employ ion-exchange resins for the solution-phase synthesis of chemical libraries. We have found these resins to be useful as reagents and/or scavengers in a variety of reactions. Nine basic ion-exchange resins were evaluated for the catalysis and purification of an amide synthesized from an acid chloride. A number of the resins examined provided products in >95%
Kanamycin−Cu(II) Complex Catalyzed Ullmann Amine Synthesis at Room Temperature: A Tool for Mechanistic Insights into Methylene Blue Degradation
作者:Huma Basheer、Sadia Shamsi、Abdul Qadir、Kalicharan Sharma、Chandra S. Azad、Amit Kumar、Imran A. Khan
DOI:10.1002/ejoc.202400328
日期:2024.8.5
The transformative potential of kanamycin−copper (II) complexes for Ullmann amine synthesis at room temperature showcases the efficient creation of diverse N−aryl compounds via SO4−• mediated generation of Cu(III)−aryl species. Additionally, it highlights the catalyst's role in degrading methyleneblue, advancing both catalytic methodologies and environmental applications.