64-10-8Relevant articles and documents
Indium(III)-Catalyzed Synthesis of Primary Carbamates and N-Substituted Ureas
Jain, Isha,Malik, Payal
supporting information, p. 93 - 97 (2021/11/26)
An indium triflate-catalyzed synthesis of primary carbamates from alcohols and urea as an ecofriendly carbonyl source has been developed. Various linear, branched, and cyclic alcohols were converted into the corresponding carbamates in good to excellent yields. This method also provided access to N-substituted ureas by carbamoylation of amines. All the products were obtained by simple filtration or crystallization, without the need for chromatographic purification. Mechanistic investigations suggest that the carbamoylation reaction proceeds through activation of urea by O-coordination with indium, followed by nucleophilic attack by the alcohol or amine on the carbonyl center of urea. The inexpensive and easily available starting materials and catalyst, the short reaction times, and the ease of product isolation highlight the inherent practicality of the developed method.
Enzyme-Inspired Lysine-Modified Carbon Quantum Dots Performing Carbonylation Using Urea and a Cascade Reaction for Synthesizing 2-Benzoxazolinone
Hasani, Morteza,Kalhor, Hamid R.
, p. 10778 - 10788 (2021/09/08)
Catalysts as the dynamo of chemical reactions along with solvents play paramount roles in organic transformations in long-lasting modes. Thus, developing effective and biobased catalysts in nontoxic solvents is highly in demand. In this report, carbon quantum dots (CQDs) functionalized with-lysine (Lys-CQDs) were generated from entirely nature-derived materials; they were demonstrated to be a promising catalyst for C-N bond formation in choline chloride urea (ChCl/U), a natural deep eutectic solvent (NADES). Among a number of synthesized CQDs, Lys-CQD turned out to be a powerful catalyst in the model reaction with aniline to afford phenyl urea. This type of transformation is important because aniline as a nucleophile has low activity, and urea is a very weak electrophile but an abundant natural source of the carbonyl moiety at the same time. The optimized reaction was performed under a highly desirable condition without using tedious and toxic workup processes at a low temperature (37 °C for aliphatic amines and 60 °C for aniline derivatives), as well as by embracing the broad scope of products in good to high yields even with weak nucleophiles such as aniline. A proposed acid-activated mechanism was suggested for the model reaction that was further confirmed by detecting ammonia as the leaving group. To show further multifunctionality of the catalyst, a cascade catalysis approach was developed for synthesizing 2-benzoxazolinone, which was furnished in a two-step transformation, starting from 2-aminophenol. Using X-ray crystallography, the structure of the final product in the cascade reaction was also determined. The catalyst was characterized using various analytical techniques including SEM, TEM, AFM, XRD, IR spectroscopy, UV-vis spectroscopy, DLS, and fluorescence spectroscopy. Measuring the acid/base sites by back titration, the catalyst was shown to be highly functionalized by the lysine functional group. The size of the catalyst was determined to be in the range of 1-8 nm, having a well-dispersed surface. In all, Lys-modified CQD, as a metal-free catalyst, was synthesized, characterized, and optimized for carbonylation, as well as a cascade reaction, under mild conditions. The whole process including catalyst synthesis and organic transformations is economically competitive and fulfills all requirements toward viability.
Synthesis of Biuret Derivatives as Potential HIV-1 Protease Inhibitors Using (LDHs-g-HMDI-Citric Acid), as a Green Recyclable Catalyst
Ghiasifar, Zahra,Salehabadi, Hafezeh,Adibpour, Neda,Alipour, Eskandar,Kobarfard, Farzad,Shoushizadeh, Mohammad Reza
, p. 48 - 59 (2020/12/07)
In this study, a novel catalyst based on layered double hydroxides (LDHs) attached by hexamethylene-1,6-diisocyanate (HMDI) and citric acid (LDHs-g-HMDI-Citric acid) is reported and used to increase the yield of biurets synthesis. Biuret derivatives 5a–n were prepared by reaction of several phenyl allophanates (3a–d), which prepared from the reaction of phenyl chloroformate and urea derivatives (2a–d), with variously substituted amines (4a–g) in the presence of LDHs-g-HMDI-Citric acid as a reusable heterogeneous catalyst at reflux condition for 60–180 min. These biurets (5a–n) were evaluated for human immunodeficiency virus type-1 (HIV-1) protease inhibitory activity by HIV-1 p24 antigen ELISA kit and six of them (5n, 5i, 5j, 5 m, 5f, and 5a) showed moderate activity on HIV-1 virus with IC50 values ranging from 55 to 100 μM compared with the azidothymidine as the reference drug (IC50 = 0.11 μM). Results of the in vitro test and docking study were in good correlation.
