It is demonstrated that o-quinones, generated by the electrochemically driven oxidation of the catechols (1a−d) at physiological pH, are rapidly scavenged by 2-mercaptobenzoxazole (3) to give related catecholthioethers (4a−d) via an EC electrochemical mechanism pathway. The electrochemical syntheses of 4a−d have been successfully performed in one-pot in ambient conditions and in an undivided cell using
In this research, synthesis, antimicrobial and antioxidant activities of a series of catecholthioethers having benzoxazole and tetrazole moieties are described. Antimicrobial activity was evaluated by minimum inhibitory concentration (MIC) assay. The synthesized compounds were tested in vitro against three Gram-positive bacteria including Staphylococcus aureus (clinical isolated), Staphylococcus aureus ATCC 25922, Enterococcus faecium (clinical isolated), and two Gram-negative bacteria including Klebsiella pneumoniae (clinical isolated) and Pseudomonas aeruginosa 27853 and the yeast Candida albicans in comparison with control drugs. Microbiological results indicated that the synthesized compounds possessed a broad spectrum of activity against the tested microorganisms at MIC values between 4—256 μg/ml. This shows compounds having tetrazole moiety were the most active against Gram-negative strains, whereas compounds having benzoxazole moiety were more active against Gram-positive ones. Also both of them showed significant antifungal activity against Candida albicans and had lower activity than the compared control drugs (Sulfamethoxazole and Fluconazole). The antioxidant activity was assessed using two methods, including, 1,1-biphenyl-2-picrylhydrazyl (DPPH) radical scavenging, and reducing power assays. Some of the catecholthioether derivatives showed antioxidant activity more than Trolox and butylated hydroxyanisole (BHA) as reference antioxidants.
Synthesis of catecholthioethers by the selective oxidation of catechols in competition with 2-mercaptobenzoxazole
作者:Esmail Tammari、Naser Mirazi、Davood Nematollahi
DOI:10.1070/mc2006v016n05abeh002343
日期:2006.1
Potassium ferricyanide acts as a selective oxidising agent for the oxidation of catechols even in the presence of 2-mercaptobenzoxazole, as an easily oxidisable thiol to produce related catechol thioethers.
Laccase-catalyzed synthesis of catechol thioethers by reaction of catechols with thiols using air as an oxidant
作者:Heba T. Abdel-Mohsen、Jürgen Conrad、Uwe Beifuss
DOI:10.1039/c3gc41968a
日期:——
The laccase-catalyzed reaction between catechols and thiols using aerial oxygen as the oxidant delivers the corresponding catechol thioethers with yields up to 96% under mild reaction conditions.