Mohamad Yusuf

Synthesis, spectral studies and in vitro antibacterial activity of steroidal thiosemicarbazone and their palladium (Pd (II)) complexes

We investigated the antibacterial activity of some new steroidal thiosemicarbazone and their Pd(II) metal complexes. Metal complexes were prepared from the reaction of steroidal thiosemicarbazone with [Pd(DMSO)(2)Cl(2)]. Coordination via the thionic sulphur and the azomethine nitrogen atom of the thiosemicarbazone to the metal ion, the thiosemicarbazone derivatives were obtained by the thiosemicarbazide with steroidal ketones. All the compounds have been confirmed by spectral data. The antibacterial activity of these compounds was first tested in vitro by the disk diffusion assay against two gram-positive and two gram-negative bacteria, and then the minimum inhibitory concentration (MIC) was determined. The results showed that steroidal complexes are better inhibit growth as compared to steroidal thiosemicarbazones of both types of the bacteria (gram-positive and gram-negative); compound Ia is better antibacterial agent as compared to amoxicillin.

Photoisomerization of allyl ethers: syntheses of vinyl ethers

Abstract A synthesis of vinyl ethers through the photoisomerization of allyl ethers is described.

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.

New bispyrazoline derivatives built around aliphatic chains: Synthesis, characterization and antimicrobial studies

AbstractThe bispyrazolines 3a–3h built around the alkyl chains of varying lengths have been synthesized from the cyclization reactions of bischalcones with phenyl hydrazine. The bischalcones 2a–2h were obtained from the Claisen–Schmidt reactions of acetophenone with various bisaldehydes 1a–1h. The intermediate bischalcones and final bisheterocyclic compounds have been characterized by means of IR, 1H-NMR, 13C-NMR, Mass (ESI) and elemental analysis. The antibacterial and antifungal activities of the synthesized compounds were also evaluated against the Klubsellia pneumoniae, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Bacillius subtilis and Aspergillius janus, Aspergillus niger and Pencillium glabrum, respectively. The antimicrobial behaviour of the bispyrazolines 3a–3h is found to be dependent on the length of internal spacer unit. Graphical AbstractSynthesis and antimicrobial behaviour of the bispyrazolines built around the aliphatic chains have been described. The antimicrobial behaviour of these bisheterocyclic compounds is found to be dependent on the length of the internal spacer unit.

Synthesis and antimicrobial studies of new N,N -(5,5 -{2,2 -(bis-alkoxy) bis(2,1-phenylene))bis(4-acetyl-4,5-dihydro-1,3,4-thiadiazole-5, 2-diyl))diacetamide

AbstractThe bisthiadiazolines 4a(a′-f′) and 4b(a′-f′) built around the various rigid chains have been synthesized in good yields by refluxing bisthiosemicarbazones 3a(a′-f′) and 3b(a′-f′) in acetic anhydride medium. The reaction of bisaldehydes 2a(a′-f′) and 2b(a′-f′) with thiosemicarbazide under alcoholic medium yielded 3a(a′-f′) and 3b(a′-f′) and the former were obtained from the reaction of 2/4-hydroxybenzaldehyde with suitable alkylating agent in the presence of anhydrous K2CO3/dry acetone and Bu4N + I −  (PTC). The intermediates and final compounds 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 prepared compounds were also evaluated against the Klubsellia pneumoniae, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Bacillius subtilis and Aspergillius janus and Pencillium glabrum strains, respectively. The formation and antimicrobial behaviour of the bisthiadiazolines 4a(a′-f′) and 4b(a′-f′) are found to be independent of nature of the internal spacer unit. Graphical AbstractThe synthesis and antimicrobial behaviour of new 1,3,4-bisthiadiazolines built around the five rigid chains have been described. The formation and antimicrobial behaviour of bisthiadiazoline derivatives are found to be independent of the nature of internal spacer unit.

Photoreorganisation of some bischromones

Abstract Photoreorganisation of 2,2′-dithienyl/diphenyl-3,3′-polymethylene-dioxychromones is described. The product formation has been found to depend upon the length of the intervening alkyl chain.

Photolysis of xylylbischromones

Photoreorganisation of xylylbischromones occurring through 1,4-biradical is described. In these bischromones, the two chromophores have been found to behave independently.

Photocyclisation of o-xylylbischromones : proximity effect

The photocyclisation of thiophene and furan substituted o-xylylbischromones is described. The reaction occurs through a 1,4-biradical species. The proximity of the two chromophores due to intramolecular complex formation affects the chemical efficiency of the reaction.

Photocyclisation of 3-alkoxythiochromones: activation for H-abstraction

Photocyclisation of 3-alkoxy-2-arylthiochromones leads to angular tetracyclic compounds through H-abstraction that requires activation by a phenyl group.

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.