No abstract

A novel multi-component synthesis of highly substituted 1,6-dihydropyrazine-2,3-dicarbonitrile derivatives starting from simple and readily available inputs is described. Thus, simply stirring an ethanol solution of 2,3-diaminomaleonitrile, a ketone, and an isocyanide in the presence of a catalytic amount of p-toluenesulfonic acid provided highly substituted 1,6-dihydropyrazine-2,3-dicarbonitrile derivatives in good to excellent yields at ambient temperature.

p-Toluenesulfonic acid catalyzed the one-pot, three-component synthesis of 3-aminoimidazo[1,2-a]pyridines and pyrazines through a condensation reaction of a 2-aminoazine, an aldehyde, and an isocyanide at room temperature. This methodology affords a number of 3-aminoimidazo[1,2-a]pyridines in reasonable yields and short reaction times without any significant optimization of the reaction conditions.

A novel one-pot pseudo-five-component synthesis of 4,5,6,7-tetrahydro-1 H-1,4-diazepine-5-carboxamide derivatives starting from simple and readily available inputs including 2,3-diaminomaleonitrile, a cyclic or acyclic ketone, an isocyanide, and water in the presence of a catalytic amount of p-toluenesulfonic acid in aqueous medium at ambient temperature in high yields is described.

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.