Synthesis and Antimycobacterial Activity of Pyridylmethylsulfanyl and Naphthylmethylsulfanyl Derivatives of Benzazoles, 1, 2, 4-Triazole, and Pyridine-2-carbothioamide/-2-carbonitrile

DBU-Promoted Deaminative Thiolation of 1H-Benzo[d]imidazol-2-amines and Benzo[d]oxazol-2-amines

A facile and efficient catalyst-/metal-/oxidant-free DBU-promoted deaminative thiolation reaction of 1H-benzo[d]imidazol-2-amines and benzo[d]oxazol-2-amines has been developed at room temperature conditions in a one-pot protocol. This practical three-component strategy represents a novel and environmentally friendly reaction pathway toward the straightforward synthesis of various 2-thio-1H-benzo[d]imidazoles and 2-thiobenzo[d]oxazoles using carbon disulfide as a sulfur source through C-N bond cleavage and C-S bond formation process. Different types of 1H-benzo[d]imidazol-2-amines, benzo[d]oxazol-2-amines, and organic bromides are suitable substrates. The gram-scale and late-stage modification experiments provide the potential applications based on this methodology in the field of organic and medicinal chemistry.

A facile sonochemical protocol for synthesis of 3-amino- and 4-amino-1,2,4-triazole derived Schiff bases as potential antibacterial agents

A facile method has been developed for the synthesis of Schiff bases derived from substituted and unsubstituted 3-amino- and 4-amino-1,2,4-triazoles. Condensation of the aminotrizoles with a variety of aromatic aldehydes afforded desired Schiff bases in excellent yields in 3-5 minutes of exposure to ultra-sound. The synthesized compounds were characterized by means of IR, 1HNMR and Mass spectrometry. The synthesized compounds were also screened for their antibacterial potential against Gram-negative (Escherichia coli, Shigella sonnei, Pseudomonas aeruginosa and Salmonella typhi) and two Gram-positive (Staphylococcus aureus and Bacillus subtilis) strains.

Synthesis and Tuberculostatic Activity Evaluation of Novel Benzazoles with Alkyl, Cycloalkyl or Pyridine Moiety

Compounds possessing benzimidazole system exhibit significant antituberculous activity. In order to examine how structure modifications affect tuberculostatic activity, a series of benzazole derivatives were synthesized and screened for their antitubercular activity. The compounds 1–20 were obtained by the reaction between o-diamine, o-aminophenol, or o-aminothiophenol with carboxylic acids or thioamides. The newly synthesized compounds were characterized by IR, ¹H-NMR, ¹³C-NMR spectra, and elemental analysis. Synthesized benzazoles were evaluated for their tuberculostatic activity toward Mycobacterium tuberculosis strains. Quantum chemical calculations were performed to study the molecular geometry and the electronic structure of benzimidazoles GK-151B, 4, 6, and benzoxazole 11, using the Gaussian 03W software (Gaussian, Inc., Wallingford, CT, USA). Three-dimensional structure of benzimidazoles 1–3, MC-9, and GK-151B was determined by ab initio calculation using Gamess-US software. The activity of the received benzimidazoles was moderate or good. All of the benzoxazoles and benzothiazoles demonstrated much lower activity. Benzoxazoles were less active by about 50 times, and benzothiazole by 100 times than the benzimidazole analogs. Quantum chemical calculations showed differences in the distribution of electrostatic potential in the benzazole system of benzimidazoles and benzoxazoles. Three-dimensional structure calculations revealed how the parity of the alkyl substituent at the C2 position impacts the activity. Benzimidazole system is essential for the antituberculosis activity that is associated with the presence of the imine nitrogen atom in N-1 position. Its replacement by an oxygen or sulfur atom results in a decrease of the activity. The parity of the alkyl substituent at the C-2 position also modifies the activity.

Synthesis, characterization, and antimicrobial evaluation of some new hydrazinecarbothioamide, 1,2,4-triazole and 1,3,4-thiadiazole derivatives

In this work, we reported the synthesis and evaluation of antibacterial and antifungal activities of three new compound series obtained from 6-(phenyl/4-chlorophenyl)imidazo[2,1-b]thiazole-3-acetic acid hydrazide: 2-{[6-(phenyl/4-chlorophenyl)imidazo[2,1-b]thiazol-3-yl]acetyl}-N-alkyl/arylhydrazinecarbothioamides (2a-d), 4-alkyl/aryl-2,4-dihydro-5-{[6-(phenyl/4-chlorophenyl)imidazo[2,1-b]thiazol-3-yl]methyl}-3H-1,2,4-triazole-3-thiones (3a-n), and 2-alkyl/arylamino-5-{[6-(phenyl/4-chlorophenyl)imidazo[2,1-b]thiazol-3-yl]methyl}-1,3,4-thiadiazoles (4a-g). The newly synthesized compounds were characterized by IR, (1)H NMR, (13)C NMR (APT), mass and elemental analysis. Their antibacterial and antifungal activities were evaluated against Staphylococcus aureus ATCC 29213, Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922, Candida albicans ATCC 10231, C. parapsilosis ATCC 22019, C. krusei ATCC 6258, Trichophyton mentagrophytes var. erinacei NCPF 375, Microsporum gypseum NCPF 580, and T. tonsurans NCPF 245. 3c, 3f, 3m, 3n, and 4e showed the highest antibacterial activity. Particularly 3c, 3f, 3g, 3k, 3n, 4a, 4e, and 4g showed the highest antifungal activity against tested fungi.

Synthesis and antimicrobial activity evaluation of new 1,2,4-triazoles and 1,3,4-thiadiazoles bearing imidazo[2,1-b]thiazole moiety

A series of 4-alkyl/aryl-2,4-dihydro-5-((6-(4-bromophenyl)imidazo[2,1-b]thiazol-3-yl)methyl)-3H-1,2,4-triazole-3-thiones (3a-i) and 2-alkyl/arylamino-5-((6-(4-bromophenyl)imidazo[2,1-b]thiazol-3-yl)methyl)-1,3,4-thiadiazoles (4a-c) were synthesized starting from 6-(4-bromophenyl)imidazo[2,1-b]thiazole-3-acetic acid hydrazide. The newly synthesized compounds were characterized by IR, (1)H NMR, mass and elemental analysis. All compounds were tested for antibacterial and antifungal activities. The antimicrobial activities of the compounds were assessed by the microbroth dilution technique. The compounds were also evaluated for antituberculosis activity against Mycobacterium tuberculosis H37Rv (ATCC 27294). The preliminary results revealed that some of the compounds exhibited promising antimicrobial activities.

The Oriented Development of Antituberculotics (Part II): Halogenated 3-(4-Alkylphenyl)-1,3-benzoxazine-2,4-(3H)-diones

Based on our previous studies, 21 new halogenated 3-(4-alkylphenyl)-1,3-benzoxazine-2,4-(3H)-diones were synthesized by the reaction of salicylanilides and methyl-chloroformate. All compounds were screened in vitro against three different strains of mycobacterium, and Free-Wilson method was used to establish structure-activity relationships. 6-Bromo-3-(4-butylphenyl)-1,3-benzoxazine-2,4-(3H)-dione 3b proved to be the most active compound of the series.

The Oriented Development of Antituberculotics: Salicylanilides

On the basis of our previous results 22 salicylanilides were synthesized. The compounds were tested for in vitro antimycobacterial activity against Mycobacterium tuberculosis, Mycobacterium kansasii, and Mycobacterium avium. The Free-Wilson method was used to evaluate structure-antimycobacterial activity relationships. 4-Chloro-N-(4-propylphenyl)salicylamide and 5-chloro-N-(4-propylphenyl)salicylamide were selected for preclinical studies.