Chemoselective reactions of 3,6-diacetylindoles towards araldehydes, hydrazine hydrate and bromine: Synthesis and antimicrobial activity of novel 6-pyridyl/6-hydrazinoacetyl/6-bromoacetyl-3-acetylindole derivatives

The exclusive formation of 6-pyridyl/6-hydrazinoacetyl/6-bromoacetylindoles 5a-f, 7a,b and 9a from 3,6-diacetylindole derivatives 1a,b reveal the chem oselective reaction of C-6-acetyl over C-3-acetyl function towards araldehy des, hydrazine hydrate and bromine, respectively. Indol-6-yl-propen-1-ones 4a-f when treated with malononitrile and ammonium acetate furnish 1-substit uted-3-acetyl-6-(2-amino-3-cyano-4-arylpyrid-6-yl)-5-methoxy-2-methylindole s 5a-f. Similarly, 3,6-diacetylindole derivatives 1a,b on reaction with hyd razine hydrate (99%) in ethanol and bromine in chloroform afford 1-substitu ted-3-acetyl-6-hydrazinoacetyl-5-hydroxy-2-methylindoles 7a,b and 3-acetyl- 6-bromoacetyl-1-(4-chlorophenyl)-5-hydroxy-2-methylindole 9a, respectively. The newly synthesised compounds are screened for their antibacterial and a ntifungal activities.