Recent developments in the nanomaterial-catalyzed green synthesis of structurally diverse 1,4-dihydropyridines

Abstract

Single pot multicomponent approaches using different nanomaterials as green catalysts for synthesis of 1,4-dihydropyridine (1,4-DHP), a privileged heterocyclic scaffold with vital biological and therapeutic applications are reviewed.

Tandem Protocol of Hexahydroquinoline Synthesis Using [H2-DABCO][HSO4]2 Ionic Liquid as a Green Catalyst at Room Temperature

“…DABCO is a cagelike tertiary amine having weak alkalinity. This cagelike structure increases the energy barrier of nitrogen inversion so the lone pair is localized and makes DABCO more susceptible toward quaternization and ionic liquid preparation and further applied in organic reactions. − Regarding the abovementioned notable properties of 1,4-DHP derivatives, their synthetic methods have been investigated in various environmental conditions. − However, most of the research studies have been done on the synthesis of 3-carboxylate derivatives of 1,4,5,6,7,8-hexahydroquinoline compared to 3-carbonitrile derivatives. 1,4,5,6,7,8-Hexahydroquinoline-3-carbonitrile was previously synthesized using NH 4 OAc, sulfonated rice husk, nanosized MgO, nano-Fe 3 O 4 @TDI@TiO 2 , citric acid/MCM-48, and K 2 CO 3 catalyst. − Despite the undeniable advantages of these processes, some disadvantages are also present, like the involvement of metal catalysts, nonrecyclable catalysts, high catalyst loading, long reaction time, high temperature, and small substrate scope.…”

Solid-state silica gel-catalyzed synthesis of fluorescent polysubstituted 1,4- and 1,2-dihydropyridines

“…The reactions are two-component and the 1,2-DHP skeleton is assembled for the first time from the mentioned reagents. All previously reported syntheses of 1,4-DHPs from the same type of reagent include solution-state reactions, 20,21 whereas solvent-free syntheses using various solid supports and catalysts, such as SiO 2 and microwaves, 22 Mg(ClO 4 ) 2 , 23 sulfonic acid functionalized SiO 2 , 24 SiO 2 –HClO 4 , 25 SiO 2 –H 2 SO 4 , 26 ordered mesoporous molecular sieves, 27 and magnetic and non-magnetic nanocatalysts, 28 are confined to the multicomponent Hantzsch and Hantzsch-like reactions. The 1,4-DHP products obtained by our reactions are highly fluorescent since they possess two electron-withdrawing substituents at the 3- and 5-positions and have no substituents at the 2- and 4-positions, which were shown as the necessary requirements for the good fluorescence properties of the 1,4-DHP framework.…”

1,4-Dihydropyridine: synthetic advances, medicinal and insecticidal properties

“…The 1,4-DHP scaffold has gained traction as a preferred choice of medicinal chemistry researchers for developing novel molecules with therapeutic signicance, and it is regarded as one of the privileged structures in the drug discovery process due to its ability to import valuable medicinal properties into molecules. [4][5][6][7][8][9][10] Privilege structures, according to the IUPAC denition, exhibit "substructural diversity, which reveal required (oen drug-like) activities on molecules comprising that feature. Mostly include a semi-rigid skeleton, on which can exist numerous hydrophobic residues without undertaking hydrophobic collapse".…”