TY  - JOUR
AU  - Bondžić, Aleksandra M.
AU  - Lazarević-Pašti, Tamara
AU  - Bondzic, Bojan P.
AU  - Čolović, Mirjana B.
AU  - Jadranin, Milka B.
AU  - Vasić, Vesna M.
PY  - 2013
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/5362
AB  - The aim of the present paper was to investigate the reaction of quercetin, the flavonol very often used as a dietary supplement, with [AuCl4](-) ions. The reaction was studied spectrophotometrically using the equimolar solutions in 1 : 1 water-methanol at pH similar to 2. The spectrophotometric data indicated the formation of the products with an absorption maximum at 295 nm in all cases, characteristic of the oxidized forms of quercetin. HPLC coupled with DAD and LC-MS analysis of the reaction products suggested that the oxidation of quercetin resulted in the generation of similar metabolites including quinone and various oxidized quercetin-solvent adducts. In addition, cyclic voltammetric measurements confirmed that under applied experimental conditions, the reduction of Au(III) to Au(0) took place. The reduction species in the reaction mixture were Au(III) ions, while Au(I) disproportionates back to Au(III) and Au(0). The newly generated Au(III) ions further oxidized 3-4-dihydroxy groups of quercetin adducts obtained after first 2e(-) oxidation, giving the final reaction products. Based on the identification of reaction products, the reaction mechanism for the oxidation of quercetin in the presence of Au(III) which involves two 2e(-) transfer processes was proposed.
T2  - New Journal of Chemistry
T1  - Investigation of reaction between quercetin and Au(III) in acidic media: mechanism and identification of reaction products
VL  - 37
IS  - 4
SP  - 901
EP  - 908
DO  - 10.1039/c2nj40742f
ER  - 

@article{
author = "Bondžić, Aleksandra M. and Lazarević-Pašti, Tamara and Bondzic, Bojan P. and Čolović, Mirjana B. and Jadranin, Milka B. and Vasić, Vesna M.",
year = "2013",
abstract = "The aim of the present paper was to investigate the reaction of quercetin, the flavonol very often used as a dietary supplement, with [AuCl4](-) ions. The reaction was studied spectrophotometrically using the equimolar solutions in 1 : 1 water-methanol at pH similar to 2. The spectrophotometric data indicated the formation of the products with an absorption maximum at 295 nm in all cases, characteristic of the oxidized forms of quercetin. HPLC coupled with DAD and LC-MS analysis of the reaction products suggested that the oxidation of quercetin resulted in the generation of similar metabolites including quinone and various oxidized quercetin-solvent adducts. In addition, cyclic voltammetric measurements confirmed that under applied experimental conditions, the reduction of Au(III) to Au(0) took place. The reduction species in the reaction mixture were Au(III) ions, while Au(I) disproportionates back to Au(III) and Au(0). The newly generated Au(III) ions further oxidized 3-4-dihydroxy groups of quercetin adducts obtained after first 2e(-) oxidation, giving the final reaction products. Based on the identification of reaction products, the reaction mechanism for the oxidation of quercetin in the presence of Au(III) which involves two 2e(-) transfer processes was proposed.",
journal = "New Journal of Chemistry",
title = "Investigation of reaction between quercetin and Au(III) in acidic media: mechanism and identification of reaction products",
volume = "37",
number = "4",
pages = "901-908",
doi = "10.1039/c2nj40742f"
}

Bondžić, A. M., Lazarević-Pašti, T., Bondzic, B. P., Čolović, M. B., Jadranin, M. B.,& Vasić, V. M.. (2013). Investigation of reaction between quercetin and Au(III) in acidic media: mechanism and identification of reaction products. in New Journal of Chemistry, 37(4), 901-908.
https://doi.org/10.1039/c2nj40742f

Bondžić AM, Lazarević-Pašti T, Bondzic BP, Čolović MB, Jadranin MB, Vasić VM. Investigation of reaction between quercetin and Au(III) in acidic media: mechanism and identification of reaction products. in New Journal of Chemistry. 2013;37(4):901-908.
doi:10.1039/c2nj40742f .

Bondžić, Aleksandra M., Lazarević-Pašti, Tamara, Bondzic, Bojan P., Čolović, Mirjana B., Jadranin, Milka B., Vasić, Vesna M., "Investigation of reaction between quercetin and Au(III) in acidic media: mechanism and identification of reaction products" in New Journal of Chemistry, 37, no. 4 (2013):901-908,
https://doi.org/10.1039/c2nj40742f . .

TY  - JOUR
AU  - Bondzic, Bojan P.
AU  - Dzambaski, Zdravko
AU  - Bondžić, Aleksandra M.
AU  - Markovic, Rade
PY  - 2012
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/5127
AB  - The a-C position in 4-oxo thiazolidinones functions as one of the three possible nucleophilic sites in these molecules. We used the inherent reactivity of alpha-C of the exocyclic double bond (a so called push pull system) to obtain bicyclic fused thiazolidinones via pi-annulation cyclization. Appropriate reaction conditions to selectively activate this position and secondary nitrogen towards N, pi-annulation were found. Furthermore, the intramolecular vinylogous iminium ion 6-exo-trig cyclization was used to access fused bicyclic precursors for the pi-annulation in order to obtain the novel tricyclic structures stereoselectively. (c) 2012 Elsevier Ltd. All rights reserved.
T2  - Tetrahedron
T1  - pi-Annulation reactions of 4-thiazolidinone enaminones in the synthesis of fused bi- and tri-cyclic compounds
VL  - 68
IS  - 47
SP  - 9556
EP  - 9565
DO  - 10.1016/j.tet.2012.09.080
ER  - 

@article{
author = "Bondzic, Bojan P. and Dzambaski, Zdravko and Bondžić, Aleksandra M. and Markovic, Rade",
year = "2012",
abstract = "The a-C position in 4-oxo thiazolidinones functions as one of the three possible nucleophilic sites in these molecules. We used the inherent reactivity of alpha-C of the exocyclic double bond (a so called push pull system) to obtain bicyclic fused thiazolidinones via pi-annulation cyclization. Appropriate reaction conditions to selectively activate this position and secondary nitrogen towards N, pi-annulation were found. Furthermore, the intramolecular vinylogous iminium ion 6-exo-trig cyclization was used to access fused bicyclic precursors for the pi-annulation in order to obtain the novel tricyclic structures stereoselectively. (c) 2012 Elsevier Ltd. All rights reserved.",
journal = "Tetrahedron",
title = "pi-Annulation reactions of 4-thiazolidinone enaminones in the synthesis of fused bi- and tri-cyclic compounds",
volume = "68",
number = "47",
pages = "9556-9565",
doi = "10.1016/j.tet.2012.09.080"
}

Bondzic, B. P., Dzambaski, Z., Bondžić, A. M.,& Markovic, R.. (2012). pi-Annulation reactions of 4-thiazolidinone enaminones in the synthesis of fused bi- and tri-cyclic compounds. in Tetrahedron, 68(47), 9556-9565.
https://doi.org/10.1016/j.tet.2012.09.080

Bondzic BP, Dzambaski Z, Bondžić AM, Markovic R. pi-Annulation reactions of 4-thiazolidinone enaminones in the synthesis of fused bi- and tri-cyclic compounds. in Tetrahedron. 2012;68(47):9556-9565.
doi:10.1016/j.tet.2012.09.080 .

Bondzic, Bojan P., Dzambaski, Zdravko, Bondžić, Aleksandra M., Markovic, Rade, "pi-Annulation reactions of 4-thiazolidinone enaminones in the synthesis of fused bi- and tri-cyclic compounds" in Tetrahedron, 68, no. 47 (2012):9556-9565,
https://doi.org/10.1016/j.tet.2012.09.080 . .