A metal-free aerobic oxidative bromination of aromatic compounds in water has been developed. Hydrobromic acid is used as a bromine source and 2-methylpyridinium nitrate ionic liquid is used as a recyclable catalyst. Water is used as the reaction mediate. This is the first report of aerobic oxidative bromination using only catalytic amount of metal-free catalyst. This system shows not only high bromine atom economy, but also high bromination selectivity. The possible mechanism and the role of the catalyst in this system have also been discussed.

A facile and efficient transition-metal-chloride/sodium-nitrite/TEMPO catalytic system for aerobic oxidative aromatisation of Hantzsch 1,4-dihydropyridines in high yields under mild conditions is described.

An Efficient Transition-Metal-Chloride/Sodium-Nitrite/TEMPO Catalytic System for Aerobic Oxidative Aromatization of Hantzsch 1,4-Dihydropyridines. -MnCl2, NiCl2, FeCl3, and several Cu(I) and Cu(II) salts are disclosed as efficient oxidation catalysts for 1,4-dihydropyridines. The solvent effects on the reaction are discussed. -(LOU, B.-H.; CHEN, S.-B.; WANG, J.; CHEN, Y.; LI*, J.-H.; J. Chem. Res. 37 (2013) 7, 409-412, http://dx.