A simple method for the oxidative aromatization of Hantzsch 1,4-dihydropyridines to the corresponding pyridines is reported using urea-hydrogen peroxide/maleic anhydride in acetonitrile.
报道了一种简单的方法,利用乙腈中的尿素-过氧化氢/马来酸酐,将Hantzsch 1,4-二氢吡啶氧化芳香化为相应的吡啶。
A wide variety of 3,5-dicarboethoxy-1,4-dihydropyridines and 3,5-diacetyl-1,4-dihydropyridines are aromatized to the pyridine derivatives by 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ) at room temperature and under microwave irradiation. An electron transfer-induced mechanism is proposed for this reaction which is influenced by the nature of the solvent, the nature of the substituents located on 3-, 4- and 5-positions of the 1,4-dihydropyridine ring, and the presence of oxygen or argon atmosphere.