A novel class of extended pi-conjugated systems: one-pot synthesis of bis-3-aminoimidazo[1,2-a]pyridines, pyrimidines and pyrazines

Abstract

Bis-3-aminoimidazo[1, 2-a] pyridines, pyrimidines and pyrazines as extended pi-conjugated systems were synthesized for the first time by a novel pseudo five-component condensation of 2-aminopyridine pyrimidines and pyrazines derivatives with terephthalaldehyde or isoph-thalaldehyde and isocyanides in the presence of p-toluene-sulfonic acid in methanol.

Homogeneous and heterogeneous catalysts for multicomponent reactions

“…[311][312][313] They have also been found to be α-amyloid formation inhibitors, GABA and benzodiazepines receptor agonist. [314][315] Lewis acids such as ZnCl2, 321 ammonium chloride, [322][323] protic acids [324][325] or ionic liquids, 326 have been used as catalysts, however in most cases the catalyst is required in stoichiometric amounts in order to achieve high yield of the target compound.…”

One‐Pot Construction of Bis‐Heterocycles through Isocyanide Based Multicomponent Reactions

“…In 2008, Ahmad Shaabani et al synthesized phenylene group bridged symmetrical BHCs comprising imidazo[1,2-a]pyridine/ pyrimidine/pyrazine structures 110. [89] Thirteen such products were obtained through p-toluenesulfonic acid-catalyzed, pseudo-five component condensation reaction of 2-aminoazines (2eq), terephthalaldehyde or isophthalaldehyde (1eq) and isocyanides (2eq) in methanol solvent media at room temperature (Scheme 57).…”

Synthesis of 1,4-phenylene bridged bis-heterocyclic compounds

“…Shaabani et al 52 have described the synthesis of 1,4-phenylene-bis(imidazo[1,2-a]pyridines), 1,4-phenylene-bis-pyrimidines, and 1,4-phenylene-bis-pyrazines 80 by a pseudo-fivecomponent condensation of 2-amino-pyridines or 2-amino-pyrimidines and/or 2-aminopyrazines 79 with terephthalaldehyde 1 and isocyanides 6 in the presence of p-toluenesulfonic acid in methanol (Scheme 21). …”