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
aerobic oxidative dehydrogenation of N-heterocycles were examined in detail. Many tetrahydroquinoline derivatives and a broad range of other N-heterocycles could be tolerated by the catalytic system using a biomass-derived solvent as a reaction medium. Newly generated mixed crystal phases, noticeably enhanced surface areas and labile lattice oxygen of the OMS-2-based nanocomposite catalysts might contribute
Synthesis of Substituted 1,4‐Dihydropyridines in Water Using Phase‐Transfer Catalyst Under Microwave Irradiation
作者:Hojatollah Salehi、Qing‐Xiang Guo
DOI:10.1081/scc-200039409
日期:2004.12.31
Abstract The synthesis of various substituted 1,4‐dihydropyridines has been achieved by the reaction of aldehydes, ethyl/methyl acetoacetates, and ammonium acetate in water using phase‐transfer catalyst undermicrowaveirradiation. Compared to the classical Hantzsch's reaction conditions, this new method consistently has the advantage of good yields and short reaction times. Bifunctionalcompounds containing
Laccase-catalyzed oxidation of Hantzsch 1,4-dihydropyridines to pyridines and a new one pot synthesis of pyridines
作者:Heba T. Abdel-Mohsen、Jürgen Conrad、Uwe Beifuss
DOI:10.1039/c2gc35950b
日期:——
laccase-catalyzed oxidation of 1,4-dihydropyridines to pyridines using aerial O2 as the oxidant exclusively delivers pyridines with yields up to 95% under mild reaction conditions. Combination of the Hantzsch 1,4-dihydropyridine synthesis with the newly developed laccase-catalyzed oxidation forms the basis of a facile and environmentally benign method for the synthesis of pyridines in one pot.
Hydrogenation was only the beginning: Hantzsch esters have now been used to transferalkyl groups to imines under mild catalytic conditions to provide a variety of amines (see scheme). Benzyl, secondary alkyl, and tertiary alkyl groups containing ether, ester, and hydroxy functionalities were transferred successfully. The use of Hantzsch esters as alkylation reagents offers a practical and complementary
Reactivity of 1,4-Dihydropyridines toward Alkyl, Alkylperoxyl Radicals, and ABTS Radical Cation
作者:C. López-Alarcón、P. Navarrete、C. Camargo、J. A. Squella、L. J. Núñez-Vergara
DOI:10.1021/tx025579o
日期:2003.2.1
tested for potential scavenger effects towardalkyl, alkylperoxyl radicals, and ABTS radical cation in aqueous media at pH 7.4. Kinetic rate constants were assessed either by UV/vis spectroscopy or GC/MS techniques. Tested compounds reacted faster toward alkylperoxyl radicals and ABTS radical cation than alkyl ones. N-Ethyl-substituted DHPs showed the lowest reactivity. Kinetic results were compared with