ABSTRACT
A heterocyclic compound is a ring structure comprising carbon and other elements such as oxygen, nitrogen, or sulphur as members of the ring(s). An interesting class of heterocyclic compound is the indole skeleton, primarily due to its chemical reactivity. This reactivity allows for modification and its wide range of biological activities. Significantly, research indicates that heterocyclic compounds containing indole moieties are being investigated for their potential as leads in drug development for the treatment of microbial infections. In this study, a series of N-methylindole and indole derivatives were synthesized. The N-methylindole imine derivatives were synthesized through a single-step synthetic approach. Furthermore, both the N-methylindole sulphonyl and the indole carboxamide derivatives were synthesized through a four-step synthetic approach. The derivatives underwent physical and spectroscopic characterization using TLC, FT-IR, and 1H and 13C NMR spectroscopy. Subsequently, the synthesized compounds were evaluated for their antimicrobial activity against various bacterial and fungal isolates.
A derivative of N-methylindole-3-imine, N-(1-methyl-1H-indol-3-yl) phenylmethamine with 40.1% yield reveals FT-IR (KBr, cm-1) 2980 (C-H stretch of the methine bonded to the phenyl ring), 2802 (very weak N-CH3 stretch absorption in the pyrrole ring), 1650 (N=C stretch), 1400 (C=C of the aromatic); 1HNMR, 600 MHz δ (ppm), 3.77 (s, 3H, N-CH3), 7.25-7.31 (m, 5H, phenyl ring protons), 7.49-7.66 (m, 4H, methine of the indole benzene ring), 7.26 (CDCl3), 7.81 (s, 1H, C-H of the pyrrole ring), 8.32 (s, 1H, methine on the phenyl ring); 13C NMR 600 MHz δ (ppm), 35.89 (N-CH3), 77.2 (CDCl3), 120-139 (carbons of the indole benzene ring and phenyl ring), 178.92 (N=C-H). N-methylindole-3-sulphonylpyrrolidine-2-methylcarboxylate with 43.8% yield showed FT-IR (KBr, cm-1), 3025- (Ar C-H), 2918 (CH3 bonded to nitrogen), 2849 (N-CH3), 1600 (C=C), 1350 (S=O of sulphone); 1HNMR 600 MHz, δ (ppm), 1.0 (s, 3H, N-CH3), 1.5 (s, 6H, proline), 1.6 (s, 1H, C-H proline), 1.9 (s, 1H, C=C-H), 4.2 (s, 3H, carbonyl-OCH3), 7.20-8.00 (m, 4H, Ar-H); 13C NMR 600 MHz., δ (ppm), 168 (MeO-C=O), 132-128 (Ar-C), 77.2 (CDCl3), 68 (N-CH3), 38-30 (N-CH2-CH2-CH2), 28 (OCH3), 15 (N-CH3), 12 (N-CH). The microbial analysis revealed that N-(1-methyl-1H-indol-3-yl)phenylmethamine and N-methylindole-3-sulphonylpyrrolidine-2-exhibited moderate activity against clinical isolates; Staphylococcus aureus, Pseudomonas aeruginosa, Bacillus subtilis, and Candida albicans.
