ABSTRACT FeNH4(SO4)2·12H2O (alum) efficiently catalyzes the one-pot three-component reaction of dimedone, aldehydes, and 3-aminocrotonate to afford 1,4-dihydropyridines. The work-up is easy, and the products are obtained in good to excellent yields and high purity. GRAPHICAL ABSTRACT

Sulfated titania nanoparticles (SO42-/TiO2 NPs) were synthesized using titanium tetraisopropoxide (TTIP) by the sol-gel method. The structure and morphology of the prepared nanocatalyst was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and Brunauer–Emmett–Teller (BET) methods as well as Fourier transform infrared (FT-IR) and energy dispersive X-ray (EDX) spectr...

An eco-friendly "on-water" protocol for efficient catalyst-free synthesis of the Hantzsch dihydropyridines from aryl, heteroaryl, alkyl, and vinylogous aldehydes has been developed with minimum auxiliary substances, toxic reagents, organic solvents, and disposal problems.

in this work, the efficiency, generality and applicability of new bronsted acidic ionic liquid (bail) 1-methyl-3-(2-(sulfooxy)ethyl)-1h-imidazol-3-ium chloride {[msei]cl} as heterogeneous and green catalyst for organic transformations are studied. herein, the following one-pot multi-component reactions in the presence of [msei]cl are investigated: (i) the synthesis of quinoxaline derivatives fr...

The title compound, C(18)H(19)NO(5), is a product of the Hantzsch reaction of p-phthalaldehyde, methyl acetoacetate, and ammonium acetate. The 1,4-dihydro-pyridine ring of the mol-ecule adopts a flattened boat conformation. The benzene ring is almost perpendicular to the 1,4-dihydro-pyridine ring; the plane through the six C atoms of the benzene ring and the plane through the four C atoms that ...

A convenient protocol for the enantioselective synthesis of 4-substituted tetrahydroquinolines has been developed. Chiral BINOL phosphoric acids promote the reduction of a wide range of 4-substituted quinolines with Hantzsch esters with good to high levels of enantioselectivity.

The synthesis of various substituted Biginelli 3,4-dihydropyrimidinone/thione and Hantzsch 1,4dihydropyridine derivatives has been achieved using a modified procedure in the presence of potassium ter-butoxide (tBuOK) as a catalyst under solvent-free conditions, in good to excellent yields.

A reagent-controlled stereodivergent carbocyclisation of aryl aldimine-derived, photocatalytically generated, α-amino radicals possessing adjacent conjugated alkenes, affording either bicyclic or tetracyclic products, is described. Under net reductive conditions using commercial Hantzsch ester, the radical species underwent a single stereoselective cyclisation to give trans-configured amino-ind...