Highly Efficient, One Pot Synthesis and Oxidation of Hantsch 1,4-Dihydropyridines Mediated by Iodobenzene Diacetate (III) Using Conventional Heating, Ultrasonic and Microwave Irradiation

Abstract

A mild, general, convenient, and efficient one-pot synthesis of 4-arylpyridines (4) is described using conventional heating, ultrasound and microwave irradiation. Aryl aldehydes (2) were efficiently condensed with ethylacetoacetate (1) and ammonium acetate in acetonitrile to give dihydropyridine intermediates (4). The latter underwent a smooth Iodobenzene Diacetate (III) mediated aromatization reaction in the same pot to afford 4-arylpyridines (4) in good to excellent yields.

Pyrazole-carboxaldehydes as versatile precursors for different pyrazole-substituted heterocyclic systems

“…Under various conditions, the Hantzsch condensation reaction of pyrazole-4-carboxaldehyde 2 with βketoester 64 and ammonium acetate or ammonia afforded the corresponding dihydropyridines 182. 131,[176][177][178][179][180][181][182][183] Similarly, N-aryl-1,4-dihydropyridines 183 were prepared by heating the 1,3-diphenyl-1H-pyrazole-4carboxaldehyde 2, ethyl acetoacetate/acetylacetone 64 and substituted anilines 184 165 Also, it was reported that the cyclocondensation of pyrazole-carboxaldehyde 2 with urea 120 or thiourea 184 120,185 and ethyl cyanoacetate 64 in the presence of sodium ethoxide 120 or potassium carbonate 185 gave the corresponding 2-oxo(thioxo)pyrimidine derivatives 185 (Scheme 79).…”

An Ambient Protocol for Polycyclic 1,4-Dihydropyridines Using a Heterogeneous Catalyst

“…They have also been reported to possess antidiabetic [18], anti-inflammatory [19], antimicrobial, calcium channel blocker [20], antitumor [21], and antitubercular [22] activities, etc. Various conventional and green protocols have been reported for the synthesis of DHPs using different catalysts such as AlCl3⋅6H2O [23], CeCl3⋅7H2O [24], Ceric ammonium nitrate [25], Fermenting baker's yeast [26], HClO4⋅SiO2 [27], HY-zeolite [28], Ionic liquids [29], K10-montmorillonite clay [30], Molecular iodine [31], magnetite/chitosan [32], Ni nanoparticles [33], Organocatalysts [34], p-TSA [35], SiO2 [36], triethylamine [37], TMSCl [38], ZnO [39], Fe-CuZSM-5 [40], microwave irradiation, and Ultrasound [41], etc. by the multi-component approach.…”