The preparation of medicinally promising spiro1,4–dihydropyridines accompanied by their
applications in biological and pharmaceutical activities is presented. Spiro1,4–dihydropyridines were
synthesized using numerous reported methods including bronested acids such as p-TSA, AcOH, nano-ranged
calixarene tetracarboxylic acid, sulfamic acid, PEG-OSO3H, tetramethylguanidinium triflate; lewis acids
including Zn(OTf)2, FeCl3, copper, alum, aluminosilicate nanoparticles, MnFe2O4 nanoparticles, manganese
ferrite nanoparticles, BF3OEt2; under alkaline conditions such as Et3N and piperidine; ionic liquids such as
[KAl(SO4)2·12H2O] and [Bmim]PF6, [MIM(CH2)4SO3H][HSO4]; and other miscellaneous procedures, for
example, microwave-assisted catalyst and solvent-free conditions, using iodine, PEG-400, and NaCl.