Some New 2-Amino-4-(N-substituted-1H- indol - 3-yl) thiophene-3-carbonitriles and their Antimicrobial Properties

Abstract

NOVEL series of 2-amino-4-(N-substituted-1H-indol-3-yl) thiophene-3-carbonitriles (3a-f) were prepared via reaction of 2-(1-(N-substituted-1H-indol-3-yl) ethylidene) malononitriles (2a-f) with sulfur (Gewald reaction). Reaction of 3a-f with formic acid, formamide or malononitrile led to the formation of fused thieno [2,3d] pyrimidin-4(3H)-ones (6a-f) thieno[2,3-d] pyrimidin-4-amines (7a-f) and thieno[2,3-d] pyridine-3-carbonitriles (8a-f), respectively. On the other hand, a series of 2-(2-(4-nitrophenyl)-4-oxothiazolidin-3-yl)-4-(N-substituted-1H-indol-3-yl) thiophene-3-carbonitriles (10af) and N-3-[3-cyano-4-(N-substituted-1H-indol-3-yl)-(2-thienyl)-4oxo-2-imino thiazolidinylidenes (12a-f), were prepared via reaction of Schiff bases 9a-f with thioglycollic acid or reaction of chloroacetamids 11a-f with potassium thiocyanate, respectively. Moreover, reaction of 3a-f with ethylenediamine yielded 3-(4,5dihydro-1H-imidazol-2-yl)-4-(N-substituted-1H-indol-3yl) thiophen-2-amines (13a-f). The antimicrobial activity of the newly synthesized compounds revealed that, 2-(2-(naphthalene-1-yl)diazenyl)-4-(Nsubstituted-1H-indol-3-yl)thiophene-3-carbonitriles (4a-f) showed potent inhibition of 25-33 and 18-26mm at a dose of 20 and 10 μg per disc, respectively towards Aspergillus fumigatus compared to reference drug cycloheximide.