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ChemistrySelect, 2019
To the memory of our colleague Prof. Alenka Luzar A series of thiourea derivatives bearing pendan... more To the memory of our colleague Prof. Alenka Luzar A series of thiourea derivatives bearing pendant hydroxyl groups was synthesized. These quadruply nucleophilic compounds underwent cyclization reactions with bromoacyl bromides, yielding two isomeric iminothiozolidinones. While the remote hydroxyl group in functionalized thioureas was not directly involved in the cyclization, it allowed us to establish control over the product formation through the choice of temperature and/or solvent. The new mode of temperaturedependent control over the product distribution was different from the classical kinetic vs thermodynamic control. A number of synthesized iminothiozolidinones underwent an unprecedented termolecular decyclization reaction in the presence of an external nucleophile and a proton to yield aminooxoethylcarbamothionates. In addition to the theoretical importance of this newly discovered reaction, there is also a practical need for these decyclized products as they are known privileged structures in the family of HIV-1 transcriptase inhibitors.
Tile antiradical activities of various antioxidants were determined using the free radical, 2.2-D... more Tile antiradical activities of various antioxidants were determined using the free radical, 2.2-Diphenyl-l-pict3,1hydrazyl (DPPI-I°). In its radical form, DPPI-I ° has an absorption band at 515 nm which disappears upon reduction by an antiradical compound. Twenty compounds were reacted with the DPPI-I ° and shown to follow one of three possible reaction kinetic types. Ascorbie acid, isoascorbic acid and isoeugenol reacted quickly with the DPPI-I ° reaching a steady state immediately. Rosmarinic acid and 6-tocopherol reacted a little slower and reached a steady state within 30 rain. The remaining compounds reacted more progressively with the DPPH ° reaching a steady state from I to 6 h. Caffeic acid, gentisic acid and gallic acid showed the highest antiradical activities with a stoichiometo, of 4 to 6 reduced DPPH ° molecules pet" molecule of antioxidant. Vanillin, phenol, y-resort3'lic acid and vanillic acid were found to be poor antiradical compounds. The stoichiometry, for the other 13 phenolic compounds varied from one to three reduced DPPH ° molecules pet" molecule of antioxidant. Possible mechanisms are proposed to explain the e.werimental results.
ChemistrySelect, 2019
To the memory of our colleague Prof. Alenka Luzar A series of thiourea derivatives bearing pendan... more To the memory of our colleague Prof. Alenka Luzar A series of thiourea derivatives bearing pendant hydroxyl groups was synthesized. These quadruply nucleophilic compounds underwent cyclization reactions with bromoacyl bromides, yielding two isomeric iminothiozolidinones. While the remote hydroxyl group in functionalized thioureas was not directly involved in the cyclization, it allowed us to establish control over the product formation through the choice of temperature and/or solvent. The new mode of temperaturedependent control over the product distribution was different from the classical kinetic vs thermodynamic control. A number of synthesized iminothiozolidinones underwent an unprecedented termolecular decyclization reaction in the presence of an external nucleophile and a proton to yield aminooxoethylcarbamothionates. In addition to the theoretical importance of this newly discovered reaction, there is also a practical need for these decyclized products as they are known privileged structures in the family of HIV-1 transcriptase inhibitors.
Tile antiradical activities of various antioxidants were determined using the free radical, 2.2-D... more Tile antiradical activities of various antioxidants were determined using the free radical, 2.2-Diphenyl-l-pict3,1hydrazyl (DPPI-I°). In its radical form, DPPI-I ° has an absorption band at 515 nm which disappears upon reduction by an antiradical compound. Twenty compounds were reacted with the DPPI-I ° and shown to follow one of three possible reaction kinetic types. Ascorbie acid, isoascorbic acid and isoeugenol reacted quickly with the DPPI-I ° reaching a steady state immediately. Rosmarinic acid and 6-tocopherol reacted a little slower and reached a steady state within 30 rain. The remaining compounds reacted more progressively with the DPPH ° reaching a steady state from I to 6 h. Caffeic acid, gentisic acid and gallic acid showed the highest antiradical activities with a stoichiometo, of 4 to 6 reduced DPPH ° molecules pet" molecule of antioxidant. Vanillin, phenol, y-resort3'lic acid and vanillic acid were found to be poor antiradical compounds. The stoichiometry, for the other 13 phenolic compounds varied from one to three reduced DPPH ° molecules pet" molecule of antioxidant. Possible mechanisms are proposed to explain the e.werimental results.