Synthesis of 1-benzyl and 1-benzoyl -3-indole derivatives with expected antimicrobial activity

ABSTRACT

Schiff's bases 2[a,b] were prepared via the reaction of 1-substituted indole-3-carboxaldehydes 1[a,b] with p-methoxyaniline in glacial acetic acid. Electrophilic addition of hydrogen bromide to compounds 2 [a,b] gave 3[a,b], which were reacted with hydrazine hydrate to yield the hydrazino derivatives 4[a,b]. Cyclization of the latter compounds using carbon disulphide and 1,2-dibromoethane gave triazolidine and triazine derivatives 5[a,b] and 6[a,b], respectively. Also, reaction of compounds 2[a,b] with thiosalicylic acid and thioglycolic acid led to the formation of benzothiazinone and thiazolidinone derivatives 7[a,b] and 8[a,b], respectively. Condensation of 8[a,b] with various arylaldehydes gave 9[a,b]-11[a,b] which condensed with hydrazine hydrate and cyclized to afford the fused pyrazolo [3,4-d] thiazole derivatives 12[a,b]-14[a,b]. Moreover, reaction of 8[a,b] with paraformal-dehyde and secondary amines, namely morpholine and N-methyl piperazine gave the corresponding Mannich's products 15[a,b] and 16[a,b], respectively. The newly synthesized compounds were investigated for their antimicrobial activity against Gram-negative and Gram-positive bacteria and Fungi using Naldixic acid, Itraconazole and Nystatin as reference drugs. Some of the synthesized compounds showed high and moderate activity against various tested bacterial and fungal strains. MIC of the highly biological active compounds was also investigated