Electroorganic Synthesis of Catecholthioethers

Abstract

[reaction: see text] 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 an environmentally friendly method with high atom economy.

Electrochemical Synthesis of 4-(Dihydroxyphenylthio)-2H-chromen-2-one Derivatives

“…These peaks are correspond to the oxidation of catechol (1a) to o-benzoquinone (2a) and vice versa within a quasi-reversible two electron process. [14][15][16][17][18][19][20][21] The oxidation of catechol (1a) in the presence of 4-mercaptocoumarin (3) as a nucleophile was studied in some details. for a 1 mM solution of 1a in the presence of 1 mM of 4-mercaptocoumarin (3).…”

“…1, curve b) that was enhanced during the repetitive recycling of potential is probably due to the formation of a thin film of product at the surface of the electrode, inhibiting, to a certain extent, the performance of the electrode process. [14][15][16][17][18][19][20][21] The overoxidation of 4a was circumvented during the preparative reaction because of the presence of the electron-withdrawing group.…”

“…12,13) A literature survey reveals that, in contrast to the widely studied, coumarin derivatives, no paper has reported the synthesis of 4-(dihydroxyphenylthio)-2H-chromen-2-one derivatives. Following our experiences in electrochemical oxidation of catechols in the presence of nucleophiles, [14][15][16][17][18][19][20][21] we envisaged that synthesis of organic compounds with both structures of catechol and coumarin might cause an enhancement of pharmaceutical properties and medicinal activities. This idea prompted us to investigate the electrochemical oxidation of catechols in the presence of 4-mercaptocoumarin as the nucleophile and we have discovered an easy and one-pot electrochemical method for the synthesis of 4-(dihydroxyphenylthio)-2H-chromen-2-one derivatives (4a-d) in high yield and purity, using this environmentally friendly method with high atom economy.…”

Clean and Green Synthesis of New Benzothiazole Derivatives via Electrochemical Oxidation of Catechol Derivatives

“…Some literature studies show that in the electrochemical synthesis involving catechol derivatives as substrate, use of carbon electrodes and applying controlled potential electrolysis in an undivided cell are preferred. [17,18] Therefore, these instrumental conditions were first selected in the optimization of other parameters In all studies, catechol (1a) was chosen as a model compound to investigate the appropriate conditions, and then the optimized conditions were applied to the other catechol (1b). Effect of pH of the electrolytic solution was studied in the range of 3.5−8.5.…”

Electrochemical Reduction of Nitroanisaldehyde at Zinc Cathode with Surface Morphology and Biological Activity

“…Modifying the surface of electrodes to provide some control over how the electrode interacts with its environment has been one of the most active areas of research interest in electro chemistry during the last 30 years [5][6][7][8][9][10][11].…”