Corrosion-protective properties of 1-phenacylmethyl-2-arylcarbamido(arylthiocarbamido)pyridinium bromides
摘要:
Inhibiting effect of 1-phenacylmethylpyridiilium bromides containing urea or thiourea substituents in the pyridinium ring on steel and zinc corrosion in sulfuric acid solutions was studied.
Synthesis of Unsymmetrical 2-Pyridyl Ureas via Selenium-Catalyzed Oxidative Carbonylation of 2-Aminopyridine with Aromatic Amines
作者:Xiaopeng Zhang、Guisheng Zhang、Desheng Li、Xueji Ma、Yan Wang
DOI:10.1055/s-0033-1338413
日期:——
2-aminopyridine and various aromatic amines is reported for the first time. The procedure employs inexpensive selenium as the catalyst, and carbonmonoxide (instead of phosgene) as the carbonyl reagent. The products are obtained in moderate to good yields via selenium-catalyzed oxidative cross-carbonylation of the substrate amines in the presence of oxygen. The selenium functions as a phase-transfer catalyst and
Scalable, One-Pot, Microwave-Accelerated Tandem Synthesis of Unsymmetrical Urea Derivatives
作者:Abhijit R. Kulkarni、Sumanta Garai、Ganesh A. Thakur
DOI:10.1021/acs.joc.6b02521
日期:2017.1.20
We report a facile, microwave-accelerated, one-pottandemsynthesis of unsymmetrical ureas via a Curtius rearrangement. In this method, one-pot microwave irradiation of commercially available (hetero)aromatic acids and amines in the presence of diphenylphosphoryl azide enabled extremely rapid (1–5 min) construction of an array of unsymmetrical ureas in good to excellent yields. We demonstrate the utility
ureas has been developed. This one‐pot one‐step cascade procedure is consisted by three individual processes: carbonylation, Curtius rearrangement, and nucleophilicaddition. A series of unsymmetrical ureas were prepared from easily available aryl iodides and amines in moderate to excellent yields. This procedure provides a convenient and practical approach for unsymmetrical urea synthesis.
Substituent Effects on Pyrid-2-yl Ureas toward Intramolecular Hydrogen Bonding and Cytosine Complexation
作者:Chia-Hui Chien、Man-kit Leung、Jen-Kuan Su、Gene-Hsiang Li、Yi-Hung Liu、Yu Wang
DOI:10.1021/jo0355808
日期:2004.3.1
constants KB ranging from 30 to 1700 M-1. Electron withdrawing substituents, such as the 4-O2NC6H4− or 1-methylpyridinium-4-yl substituent, preferentially facilitate the intermolecular cytosine complexation with large binding constants.
吡啶-2-基脲两种构象异构体之间的平衡,所述(ê,Ž)和(Ž,Ž)的形式,已经研究了在DMF- d 7在- 70℃。他们中的大多数人都不太喜欢(E,Z)形式,其平衡常数K i在1-2附近。然而,发现1-甲基-2-(3-(吡啶-2-基)脲基)碘化吡啶鎓(12)的K i值为14.2±1.2。那是其他数量级的1个数量级,这表明带正电荷的1-甲基吡啶-2-基取代基将促进(E,Z)形成形式。吡啶-2-基脲与DMF- d 7中的胞嘧啶结合,结合常数K B为30到1700 M - 1。吸电子取代基,例如4-O 2 NC 6 H 4-或1-甲基吡啶-4-基取代基,以较大的结合常数优先促进分子间胞嘧啶的络合。