Photoinduced synthesis of new diisochromenochromen-4-ones and their antimicrobial activities.

The diisochromenochromen-4-one 3a-3b, 4a-4c, 5a-6a & 7 have been prepared from the photocyclization reaction of bischromen-4-one 2a-2e. The later compounds are obtained from the O-alkylation of the suitable 3-hydroxy-2-aryl-4H-chromen-4-one 1a-1e with 4,4'-bischloromethyl-diphenyl in dry acetone, anhydrous K2CO3, and PTC (Bu4N⁺I⁻) under refluxing conditions. The structures of compounds 2a-2e, 3a-3b, 4a-4c, 5a-6a & 7 have been characterized from the rigorous analysis of their IR, ¹H-NMR, ¹³C-NMR, ESI-Mass, and elemental analysis. The antibacterial and antifungal activities of the synthesized products were also evaluated against the Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Bacillus subtilis, and Aspergillus janus and Penicillium glabrum, respectively. Some of the tested compounds showed significant activity against the above-said microorganisms.

New 1,3,4-bisthiadiazolines: synthesis, characterization and antimicrobial evaluations.

The bisthiadiazolines 4a-4g have been synthesized in good yields from the cyclization reactions of bisthiosemicarbazones 3a-3g with acetic anhydride. The condensation reaction of dibenzaldehydes 2a-2g with thiosemicarbazide in alcoholic medium provided 3a-3g and former were obtained from the O-alkylation of 3-hydroxybenzaldehyde with suitable 1,ω-dibromoalkanes under alkaline conditions in the presence of dry EtOH/DMF. The intermediates 3a-3g and bishetrocyclics 4a-4g were also screened for their in vitro antimicrobial activities against seven bacterial strains (Klubsellia pneumoniae, Pseudomonas aeruginosa, Escherichia coli, Straphylococcus aureus, Bacillius subtilis, Pseudomonas fluorescens and Streptoccus pyrogens) and five fungi strains (Aspergillius janus, Pencillium glabrum, Fusarium oxysporum, Aspergillus sclerotiorum, Aspergillus niger). The compounds 3f, 3g, 4f &4g were found to be significantly active against the tested microorganisms.