Hantzsch Reaction Starting Directly from Alcohols through a Tandem Oxidation Process

Abstract

A Brønsted acidic ionic liquid, 3-(N,N-dimethyldodecylammonium) propanesulfonic acid hydrogen sulphate ([DDPA][HSO 4 ]), has been successfully applied to catalyze sequential oxidation of aromatic alcohols with NaNO 3 followed by their condensation with dicarbonyl compound and ammonium acetate. The corresponding pyridine analogues of Hantzsch 1,4-dihydropyridines could be obtained as a major product with high yields by the multicomponent reaction. The present work utilizing alcohols instead of aldehyde in Hantzsch reaction is a valid and green alternative to the classical synthesis of the corresponding pyridine analogues of Hantzsch 1,4-dihydropyridines.

An Efficient Method for The Synthesis of Dihydropyridine by Hantzsch Reaction with Fe/SiO2 Nano Heterogeneous Catalysts

“…The search for new readily available and green methods is still ongoing [5], thus in this study, a new catalyst Fe/SiO2 was prepared by simple impregnation method was developed and evaluated for its catalytic activity for the title reaction. The Hantzsch condensation for three substrate's of different functionality were studied namely benzaldehyde, p-anisaldehyde and toulaldehyde at reflux in ethanol solvent (Scheme 1).…”

“…Hantszch reaction is a synthetic method of synthesizing dihydropyridines (DHPs) in a one-thesis of DHPs, of which most of them are limited to the modification and optimization of the Hantzsch multicomponent synthesis between an aldehyde, a 1,3-dicabonyl compound, and a source of ammonia [3,5]. Preparation of nifedipine, a dihydropyridine calcium channel blocker, acetoacetic acid methyl ester, methanol, and ammonia is used [1].…”

“…Preparation of nifedipine, a dihydropyridine calcium channel blocker, acetoacetic acid methyl ester, methanol, and ammonia is used [1]. Some of the efficient methods reported for the synthesis of DHPs made use of metal triflates, I2, CAN-Cerium ammonium nitrate, PPh3Triphenyl phosphine, L-proline, PoylPhosphoric acid supported silica-PPA-SiO2, Lanthanum oxide -La2O3 and nickel nanoparticles [3,5]. Numerous catalysts have so far been evaluated for the title reaction with Fe3O4/silica sulfonic acid nanocomposite [6], Fe2O3, CuO, ZnO [1], and Fe3O4/SiO2-NH2 nanocomposite [7].…”