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Triiodoisocyanuric acid (TICA) controlled one-pot and easy-operational protocol has been developed for the synthesis of substituted phenylquinoxalines (3a-3i) and phenyl-[1,2,5]thiadiazolo[3,4-f]quinoxaline (5a-5f) from styrenes with o-phenylenediamine and benzo[c][1,2,5]thiadiazole-4,5-diamine respectively. The reaction involves co-bromination and oxidation for the formation of an a-bromo ketone as an intermediate in the presence of triiodoisocyanuric acid, followed by condensation with the o-phenylenediamine and benzo[c][1,2,5]thiadiazole-4,5-diamine for the formation of phenylquinoxalines (3a-3i) and phenyl-[1,2,5]thiadiazolo[3,4-f]quinoxaline (5a-5f) in 55-79% yield. This protocol environmentally benign and economically viable. Substituted quinoxalines were obtained in good to excellent yields with wide substrate scope and functional-group tolerance.

A series of 11H-xantheno[2,1-c][1,2,5]selenadiazol-11-one derivatives (Va–m) that incorporate a variety of substituents have been synthesized under both conventional heating and microwave irradiation procedures. All these analogs were evaluated for their antimicrobial activity against the Gram-positive bacteria Bacillus subtilis (BS), Staphylococcus aureus (SA), and Staphylococcus epidermidis (SE), against the Gram-negative bacteria Escherichia coli (EC), Pseudomonas aeruginosa (PA), and Klebsiella pneumonia (KP), and against the fungal species Candida albicans (CA), Candida rugosa (CR), Rhizopus oryzae (RO), and Aspergillus niger (AN) and antitubercular activity against MTB H37Rv. Analog, 7,9-dimethoxy-11H-xantheno[2,1-c][1,2,5]selenadiazol-11-one (Vc) was identified as a potent antibacterial agent (MIC[BS] = 2.5 µg/mL, MIC[SA] = 10 µg/mL, MIC[SE] = 2.5 µg/mL, MIC[EC] = 5 µg/mL, MIC[PA] = 10 µg/mL, MIC[KP] = 2.5 µg/mL), and a potent antifungal agent (MIC[CA] = 15 µg/mL, MIC[CR] = 15 µg/mL, MIC[RO] = 10 µg/mL). Another analog, 7,9-dimethyl-11H-xantheno[2,1-c][1,2,5]selenadiazol-11-one (Vj) was also identified as a potent antibacterial agent (MIC[BS] = 2.5 µg/mL, MIC[SA] = 15 µg/mL, MIC[SE] = 2.5 µg/mL, MIC[EC] = 10 µg/mL, MIC[PA] = 15 µg/mL, MIC[KP] = 20 µg/mL), and a potent antifungal agent (MIC[CA] = 2.5 g/mL, MIC[CR] = 10 µg/mL MIC[RO] = 15 µg/mL and MIC[AN] = 10 µg/mL). Based on the MIC data analogs, 7,9-dimethoxy-11H-xantheno[2,1-c][1,2,5]selenadiazol-11-one (Vc) and 7,9-dimethyl-11H-xantheno[2,1-c][1,2,5]selena-diazol-11-one (Vj) were identified as the most potent antimicrobial agents in the series. All these 11H-xantheno[2,1-c][1,2,5]selenadiazol-11-one derivatives (Va–m) were also evaluated for their antitubercular activity against MTB H37Rv. Analogs, 7,9-dimethoxy-11H-xantheno[2,1-c][1,2,5]selenadiazol-11-one (Vc) and 7,9-dimethyl-11H-xantheno[2,1-c][1,2,5]selenadiazol-11-one (Vj) showed MIC of 3.12 µg/mL. These results suggest that analogs, 7,9-dimethoxy-11H-xantheno[2,1-c][1,2,5]selenadiazol-11-one (Vc) and 7,9-dimethyl-11H-xantheno[2,1-c][1,2,5]selenadiazol-11-one (Vj) may be a potential multifunctional ligands for the development of highly effective antimicrobial and antitubercular activity.

A three-component cascade reaction for the synthesis of 1,3,4-selenadiazoles and their derivatives from arylaldehydes, hydrazine, and elemental selenium by using molecular iodine is reported. This strategy is operationally simple, well-suited to a wide range of functional groups, and provides the desired products in moderate to excellent yields. The proposed mechanism predicts that the reaction tolerated a radical process.

A three-component cascade reaction for the synthesis of 1,3,4-selenadiazoles and their derivatives from arylaldehydes, hydrazine, and elemental selenium by using molecular iodine is reported. This strategy is operationally simple, well-suited to a wide range of functional groups, and provides the desired products in moderate to excellent yields. The proposed mechanism predicts that the reaction tolerated a radical process.

A series of novel quinazolin-4(3H)-one derivatives (4a-4j) were synthesized and were screened for their in vitro antibacterial activity against Gram-positive bacterial strains (Bacillus subtilis, Staphylococcus aureus, and Streptococcus pyogenes), and Gram-negative bacterial strains (Escherichia coli, Klebsiella pneumonia, S. typhimurium) and antifungal against Aspergillus niger, Candida albicans, Aspergillus flavus (Fungi). The compound 4c has been identified as potent antimicrobial agent. All the synthesized compounds were also studied for their In vitro antitubercular activity against MTB H37Rv. Compounds 4c and 4 g were identified as potent antitubercular agent with MIC value 0.78 μM and 1.56 μM. Additionally, data obtained during molecular docking studies are very encouraging with respect to potential utilization of these compounds to help overcome microbe resistance to pharmaceutical drugs, as clearly noted in this manuscript.

A series of 8,9-dihydro-2-(2-oxo-2H-chromen-3-yl)-5-aryl-3H-chromeno[2,3-d]pyrimidine-4,6(5H,7H)-diones (5a-j) have been synthesized by the reaction of 2-amino-5,6,7,8-tetrahydro-5-oxo-4-aryl-4H-chromene-3-carbonitrile (4a–j) with coumarin-3-catboxylic acid under neat conditions employing Bronsted acidic ionic liquid (4-sulfobutyl)tris(4-sulfophenyl)phosphonium hydrogen sulfate as catalyst. Structures of all the compounds were established on the basis of analytical and spectroscopic data. All the compounds were evaluated for their in vitro antimicrobial activity against different bacterial and fungal strains.