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101.
Auto de-bromine-coupling reactions of 1-aryl-7-bromocycloheptenes to a new series of [7-6-6] tricyclic system were described. A variety of substituents at the para-position of the phenyl were amenable to this transformation, including electron-donating groups and halides. The presence of electron-donating groups resulted in a more efficient reaction, with higher yields than the case of halides. 相似文献
102.
Suresh Babu Meruva Ramamohan Mekala Akula Raghunadh K. Raghavendra Rao Vilas H. Dahanukar T.V. Pratap U.K. Syam Kumar P.K. Dubey 《Tetrahedron letters》2014
Total synthesis of ent-diospongin A and epimer-diospongin B has been accomplished in good yield with high optical purity. The key steps of diospongin synthesis involve Julia–Kocienski olefination, Weinreb amide formation, Grignard reaction, reduction, acetonide deprotection, Lewis acid catalyzed cyclization, and Wacker oxidation. 相似文献
103.
1-Carbamoyl-1H-benzotriazole (benzotriazole-1-carboxamide, 2a), an effective carbamoyl chloride substitute, and a range of its analogs can be synthesized in good yields in two very simple steps from 1,2-diaminobenzene. The facile preparation of the intermediate o-aminophenylurea is key to this process. A preliminary study of the reactivity of 2a has shown that once in solution in tetrahydrofuran (THF), the 1-carbamoyl isomer equilibrates to give a mixture of both 1- and 2-isomers. If the solvent is ethanol or water, equilibration occurs rapidly compared to the ultimate formation of solvolysis products. 相似文献
104.
Almir S. Gazizov Andrey V. Smolobochkin Julia K. Voronina Alexander R. Burilov Michail A. Pudovik 《合成通讯》2013,43(10):1215-1221
1-(4,4-Diethoxybutyl)-3-alkylureas undergo intramolecular cyclization in the presence of trifluoroacetic acid and various phenols, leading to the new N-alkyl-2-arylpyrrolidine-1-carboxamides with moderate to excellent yields. It was found that these compounds undergo spontaneous solid-phase epimerization at room temperature. Advantages of the proposed approach are mild reaction conditions and no need for expensive reagents or catalysts. 相似文献
105.
106.
CO2的固定和转化具有重要研究意义,特别是采用廉价且良好生物相容性的金属催化剂将其转化为有用的有机化合物.本工作报道采用商品化ZnEt2(1.0 mol%)可促进CO2的硅氢化反应生成甲氧基硅醚,以及CO2为C1合成子的有机胺甲酰化或脲化反应生成酰胺或脲类化合物.在1.0 mol% ZnEt2存在下,CO2和(EtO)3SiH发生硅氢化反应,一锅选择性还原为甲氧基硅醚(CH3OSi(OEt)3).考察了反应条件的影响,在1.0 MPa CO2起始压力下,90℃反应7 h,甲氧基硅醚的产率达到约90%.当上述反应体系中存在有机胺时,则发生了CO2为C1合成子的的有机胺甲酰化或脲化反应.当采用二级有机胺为底物时,反应生成酰胺类产物;当一级有机胺为底物时,反应主要生成脲类产物.考察了反应底物取代基的影响,含脂肪基和芳香基的二级有机胺均可发生甲酰化反应,芳香基的对位含给电子取代基时明显有利于该甲酰化反应.含脂肪基和芳香基的一级有机胺均可发生脲化反应,芳香基对位取代基的电子性质对脲化反应的影响规律不如在甲酰化反应中的明显. 相似文献
107.
Xin Ming Zhou Zhi Bing Zheng Hong Ying Liu Wu Zhong Jun Hai Xiao Li Li Wang Song Li 《中国化学快报》2007,18(8):905-908
A new series of compounds,1-aryl-3-(3,4-dihydro-2H-chromen-5-yl) ureas,have been synthesized and their structures were confirmed by FAB-MS and ~1H NMR.The preliminary pharmacological screening showed that these compounds inhibited TNF-αproduction in lipopolysaccharide (LPS)-stimulated THP-1 cells. 相似文献
108.
Dr. Jimmy E. Jakobsson Dr. Sanjay Telu Dr. Shuiyu Lu Dr. Susovan Jana Dr. Victor W. Pike 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(40):10369-10376
Effective methods are needed for labelling acyclic ureas with carbon-11 (t1/2=20.4 min) as potential radiotracers for biomedical imaging with positron emission tomography (PET). Herein, we describe the rapid and high-yield syntheses of unsymmetrical acyclic [11C]ureas under mild conditions (room temperature and within 7 min) using no-carrier-added [11C]carbonyl difluoride with aliphatic and aryl amines. This methodology is compatible with diverse functionality (e. g., hydroxy, carboxyl, amino, amido, or pyridyl) in the substrate amines. The labelling process proceeds through putative [11C]carbamoyl fluorides and for primary amines through isolable [11C]isocyanate intermediates. Unsymmetrical [11C]ureas are produced with negligible amounts of unwanted symmetrical [11C]urea byproducts. Moreover, the overall labelling method tolerates trace water and the generally moderate to excellent yields show good reproducibility. [11C]Carbonyl difluoride shows exceptional promise for application to the synthesis of acyclic [11C]ureas as new radiotracers for biomedical imaging with PET. 相似文献
109.
Prof. Masamichi Yamanaka Kazushige Yanai Yusuke Zama Junko Tsuchiyagaito Dr. Masaru Yoshida Dr. Ayumi Ishii Prof. Miki Hasegawa 《化学:亚洲杂志》2015,10(6):1299-1303
Hierarchical self‐assembly of an amphiphilic tris‐urea in aqueous media is shown. A mixture of the amphiphilic tris‐urea and an alkaline solution gave a viscous solution composed of fibrous aggregates. This viscous solution transformed into supramolecular hydrogels, which are capable of hierarchically organizing into higher‐order aggregates in response to several cationic triggers. The resulting supramolecular hydrogels were relatively stiff and their storage moduli attained over 103 Pa. The stimuli‐responsive and optical properties of the resulting hydrogels were influenced by the cationic trigger. Proton and calcium ion triggers gave pH‐ and chemical stimuli‐responsive hydrogels, respectively. A terbium ion trigger also provided a highly luminescent hydrogel through energy transfer from the tris‐urea to terbium. 相似文献
110.
Christopher B. KellyChristopher Lee Nicholas E. Leadbeater 《Tetrahedron letters》2011,52(36):4587-4589
A method for direct preparation of diaryl sulfides from aryl iodides using potassium thiocyanate as a sulfur-transfer agent is reported. A catalyst system comprising of a simple copper salt, tetrabutylammonium bromide as a phase-transfer agent and water as the solvent is used. Microwave heating at 200 °C for 60 min allows for the conversion of a range of aryl iodides to the corresponding diaryl sulfides. 相似文献