Isocyanates are prepared directly from amines in a facile process which involves the reaction with halosilyl compounds to form novel halosilyl carbamates. The isocyanate may then be derived from the carbamate intermediate by gentle heating. In accordance with one aspect of the invention, isocyanates can be formed which contain a further reactive functional moiety, such as hydroxyl, amino, mercapto, nitro, sulfonamido, amido, carboxyl or the like.
Copper(I)-Catalyzed Four-Component Coupling Using Renewable Building Blocks of CO<sub>2</sub>
and Biomass-Based Aldehydes
作者:Qiumin Wu、Jinzhu Chen、Xuhong Guo、Yisheng Xu
DOI:10.1002/ejoc.201800461
日期:2018.6.29
Furyl‐containing oxazolidinones, bisoxazolidinone, and polyoxazolidinone were obtained by copper‐promoted four‐componentcoupling using renewable building blocks of CO2 and biomass‐based aldehydes.
Ureaderivatives are obtained in mild to good yield from the reactions of primary aliphatic amines with CO2 in the absence of any catalysts, organic solvents or other additives. To optimize reaction conditions, experimental variables including temperature, pressure, the concentration of amine, reaction time etc. were studied. Satisfactory yields were obtained at the optimized conditions that are comparable
ammonium carbamates with trimethylchlorosilane. Trimethylsilyl NN-dimethylcarbamate can be used for silylation of alcohols,phenols, and carboxylicacids. The silycarbamates react with carboxylicacid halides to give the corresponding acide amides. The reaction of trimethylsilyl carbamates with carboxylicanhydrides give the corresponding silyl carboxylate and acid amide, while the reaction with dicarboxylic
Integration of CO
<sub>2</sub>
Reduction with Subsequent Carbonylation: Towards Extending Chemical Utilization of CO
<sub>2</sub>
作者:Xian‐Dong Lang、Liang‐Nian He
DOI:10.1002/cssc.201800902
日期:2018.7.11
fixation of CO2, although enormous progress has been achieved in this field. In view of the widespread applications of CO in a myriad of industrial carbonylation processes, an alternative strategy is proposed in which CO2reduction to CO is combined with carbonylation with CO generated ex situ, which affords efficiently pharmaceutically and agrochemically attractive molecules. As such, CO2 in this study
目前,尽管在该领域已经取得了巨大的进步,但是扩大CO 2的化学固定范围仍然是一个挑战。鉴于CO在无数工业羰基化方法中的广泛应用,提出了另一种策略,其中将CO 2还原为CO与羰基化与非原位生成的CO结合,从而有效地提供了药学和农业化学上有吸引力的分子。因此,CO 2在这项研究中,三氯硅烷在封闭的两室反应器中使用CsF到CO有效地还原了CO。随后,钯催化的氨基羰基化,芳基碘化物的羰基化Sonogashira偶联以及铑(I)介导的Pauson–Khand型反应顺利进行,分别产生了酰胺,炔酮和双环环戊烯酮。此外,形成的炔酮可进一步成功转化为一系列杂环,例如吡唑,3a-羟基异恶唑并[3,2 - a ]异吲哚-8-(3a H)-one衍生物和嘧啶类化合物。该协议的显着特征包括操作简便,效率高和相对广泛的应用范围,这代表了CO 2转化的替代途径。