56-57-5Relevant articles and documents
Nitration of quinoline 1-oxide: Mechanism of regioselectivity
Yokoyama, Akihiro,Ohwada, Tomohiko,Saito, Shinichi,Shudo, Koichi
, p. 279 - 283 (1997)
The acidity dependence of orientation in the nitration of quinoline 1- oxide was investigated by using the trifluoromethanesulfonic acid (TFSA)- trifluoroacetic acid (TFA) system and the antimony pentafluoride (SbF5)- TFSA system. These systems provide a wider range of acidity than that of aqueous sulfuric acid. Comparison of the behavior of quinoline 1-oxide and 1- methoxyquinolinium triflate in acidic and neutral media demonstrated that O- protonated quinoline 1-oxide is nitrated at the 5- and 8-positions, and the free (unprotonated) molecule is nitrated at the 4-position. This result is consistent with theoretical expectation. It was also discovered that nitration at the 5-position increasingly predominates over that at the 8- position as the acidity is increased.
Regioselective Cyanation of Six-Membered N-Heteroaromatic Compounds Under Metal-, Activator-, Base- and Solvent-Free Conditions
Sarmah, Bikash Kumar,Konwar, Monuranjan,Bhattacharyya, Dipanjan,Adhikari, Priyanka,Das, Animesh
supporting information, p. 5616 - 5625 (2019/11/22)
A regioselective cyanation of heteroaromatic N-oxides with trimethylsilyl cyanide has been developed to obtain 2-substituted N-heteroaromatic nitrile without the requirement of any external activator-, metal-, base-, and solvent. The present protocol is a straightforward, one-pot heteroaromatic C?H cyanation process, and proceeds smoothly in conventional heating but also under microwave irradiation with shorter reaction times. This approach now allows access to a broad class of quinoline N-oxides and other heteroarene N-oxides with high to good yields and can also be scaled up to obtain gram quantities. Further application of this process was observed and utilized in late-stage cyanation of the anti-malarial drug quinine as well as transformation of the 2-cyanoazines to a series of biologically important molecules. Based on the experimental observations, a plausible mechanism has also been proposed highlighting the dual role of trimethylsilyl cyanide as a nitrile source and as an activating agent. (Figure presented.).
Copper-catalyzed direct amination of quinoline N-oxides via C-H bond activation under mild conditions
Zhu, Chongwei,Yi, Meiling,Wei, Donghui,Chen, Xuan,Wu, Yangjie,Cui, Xiuling
supporting information, p. 1840 - 1843 (2014/05/06)
A highly efficient and concise one-pot strategy for the direct amination of quinoline N-oxides via copper-catalyzed dehydrogenative C-N coupling has been developed. The desired products were obtained in good to excellent yields for 22 examples starting from the parent aliphatic amines. This methodology provides a practical pathway to 2-aminoquinolines and features a simple system, high efficiency, environmental friendliness, low reaction temperature, and ligand, additives, base, and external oxidant free conditions.
