Metal-Free Oxidation of Urazole and 1,4-Dihydropyridine Derivatives Under Mild and Heterogeneous Conditions by Nitro Urea, Derived from Urea Nitrate, and Silica Sulfuric Acid

. A. Ghorbani-Choghamarani, M. A. Zolfigol, M. Hajjami S. Rastgoo and S. Mallakpour Lette. Org. Chem., 2010, 7, 249-254. Metal-Free Oxidation of Urazole and 1,4-Dihydropyridine Derivatives Under Mild and Heterogeneous Conditions by Nitro Urea, Derived from Urea Nitrate, and Silica Sulfuric Acid