A series of 2,3-dihydro-1,5-benzodiazepine derivatives have been synthesized and characterized using IR, NMR, GC-MS, single crystal XRD, and microanalysis. The results of their antibacterial activity against methicillin-resistance Staphylococcus aureus, Escherichia coli, Klebsiella pneumoniae, Bacillus subtilis, Streptococcus mutans, Pseudomonas aeruginosa, Salmonella typhi, and Streptococcus pyrogens indicated that most of the compounds were bacteriostatic (0.1254mg/mL) and also exhibited good biofilm inhibition (0.2172.69). The compounds were found to be synergistic when used in combination with other antibiotics. The antiproliferative and cytotoxic effects were also investigated against PC-3 prostate cancer and RAW 264.7 macrophage cell lines, respectively, using the MTT assay. Apart from compounds 6 and 7, a good number of the compounds (1, 2, 3, 4, 5, and 8) were selectively toxic to the prostate cancer cells at 20µM, whilst sparing the normal cells. Compound 3 demonstrated the highest antiprostate cancer effect by reducing the viability of PC-3cells to (13.75), which was followed by compounds 1 (47.72), 2 (48.18), 4 (62.61), 5 (66.70), and 8 (69.55).

In an attempt to synthesize a 2-substituted benzimidazole from the reaction of o-phenylenediamine and isophthalic acid in the presence of acetone and ethanol under microwave irradiation, a salt of the isophthalate ion and 2,2,4-trimethyl-2,3-dihydro-1H-1,5-benzodiazepin-5-ium ion was obtained. The condensation of two moles of acetone with the amine groups resulted in the formation of the benzodiazepine which crystallized as an iminium cation forming a salt with the isophthalate anion. The formation of benzodiazepine was also confirmed by performing the reaction of o-phenylenediamine with excess acetone in ethanol under conventional heating conditions. The compounds were characterized by NMR, FTIR, HRMS and microanalysis as well as X-ray crystallography. The reaction mechanism leading to the formation of benzodiazepine is also discussed.

Benzimidazole or diamide from a reaction of diamines and carboxylic acids or acid chlorides: crystal structures and theoretical studies

Synthesis, characterization and DPPH scavenging activity of some benzimidazole derivatives