Metal-Free Synthesis of Unsymmetrical Ureas and Carbamates from CO<sub>2</sub> and Amines via Isocyanate Intermediates
作者:Yiming Ren、Sophie A. L. Rousseaux
DOI:10.1021/acs.joc.7b02905
日期:2018.1.19
A mild and metal-free synthesis of aryl isocyanates from arylamines under an atmosphere of CO2 was developed. The carbamic acid intermediate, derived from the arylamine starting material and CO2 in the presence of DBU, is dehydrated by activated sulfonium reagents to generate the corresponding isocyanate. The latter can be detected by in situ IR and trapped by various amines and alcohols to make unsymmetrical
Shielding Effect of Micelle for Highly Effective and Selective Monofluorination of Indoles in Water
作者:Pranjal P. Bora、Manisha Bihani、Scott Plummer、Fabrice Gallou、Sachin Handa
DOI:10.1002/cssc.201900316
日期:2019.7.5
Highly selective direct monofluorination of indoles and arenes was developed through an approach that allows site‐specific solubility of substrate and fluorine source in the micelle. This approach was highly selective for a broad range of substrates with excellent functional group tolerance. Differences in binding constant and solubility of indoles and arenes in the micelle allowed the fine‐tuning
A Synthetic Approach to <i>N</i>-Aryl Carbamates via Copper-Catalyzed Chan–Lam Coupling at Room Temperature
作者:Soo-Yeon Moon、U. Bin Kim、Dan-Bi Sung、Won-Suk Kim
DOI:10.1021/jo502828r
日期:2015.2.6
catalyst. The reaction proceeds readily in an open flask at room temperature without additional base, ligand, or additive. Rapid access to urea analogues via a two-step one-pot procedure is enabled by reacting N-arylcarbamates with aluminum–amine complexes. In addition, among several boronic acid derivatives prepared, dimethylphenyl boronate was found to react rapidly in its reaction with benzyl azidoformate
Evidence That Protons Can Be the Active Catalysts in Lewis Acid Mediated Hetero-Michael Addition Reactions
作者:Tobias C. Wabnitz、Jin-Quan Yu、Jonathan B. Spencer
DOI:10.1002/chem.200305407
日期:2004.1.23
mechanism of Lewis acid catalysed hetero-Michael addition reactions of weakly basic nucleophiles to alpha,beta-unsaturated ketones was investigated. Protons, rather than metal ions, were identified as the active catalysts. Other mechanisms have been ruled out by analyses of side products and of stoichiometric enone-catalyst mixtures and by the use of radical inhibitors. No evidence for the involvement
Efficient Cs2CO3-promoted solution and solid phase synthesis of carbonates and carbamates in the presence of TBAI
作者:Ralph N Salvatore、Feixia Chu、Advait S Nagle、Elona A Kapxhiu、Richard M Cross、Kyung Woon Jung
DOI:10.1016/s0040-4020(02)00286-7
日期:2002.4
Novel solution and solid-phase methods for the synthesis of carbonates and carbamates were developed using cesium bases and TBAI via a three-component coupling. Cesium carbonate not only promoted successful carbonylations of alcohols and carbamations of amines, but also suppressed common side reactions traditionally seen using existing protocols. Various alcohols and amines were examined, using a wide