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Unformatted text preview: APPLICATION OF SUZUKI COUPLING REACTION FOR PREPARATION OF SOME ARYLCHRYSIN ANALOGUES Thanh-Dao Tran, 1, * Haeil Park 2 1 Department of Pharmaceutical Chemistry, Faculty of Pharmacy, University of Medicine and Pharmacy at Ho Chi Minh City, 41 Dinh Tien Hoang, Dist. 1, Ho Chi Minh City, Vietnam. 2 Department of Medicinal Chemistry, School of Pharmacy, Kangwon National University, Chuncheon 200-701, South Korea. * Correspondence to Thanh-Dao Tran, email: thanhdaot@yahoo.com ABSTRACT A new class of flavone which possess an aryl radical substituted in the A ring via C-C bond, arylchrysin analogues, has been synthesized from chrysin by Suzuki coupling reaction in three to five steps. Firstly, methylation or benzylation reaction was applied on chrysin to protect hydroxyl phenol moiety. Then, halogenation by iodine or bromine in anhydrous acetic acid was performed to obtain halogenated chrysin. Finally, intermediate compounds were treated with areneboronic derivatives catalyzed by palladium tetrakits to generate arylchrysin analogues with high yields. Key words: arylchrysin, carbon-carbon coupling Suzuki reaction. INTRODUCTION Chrysin (5,7-dihydroxyflavone), a naturally wide distributed flavonoid, has been reported to have many different biological activities such as anti-inflammatory , anti-oxidant, anti-allergy and anti-cancer activity 1-2 ... For the anti-inflammatory effect, it has been showed that chrysin acts as an agonist of PPAR- which results in down-regulation of the key pro-inflammatory enzymes, inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2, prostaglandin synthase) 3-4 . Furthermore, some chrysin derivatives such as wogonin (8- methoxychrysin), and baicalein (6-hydroxychrysin), Oroxylin A (6-methoychrysin) ( Figure 1 ), found in the nature have demonstrated their inhibition of PGE 2 production stronger than those of chrysin. 5-6 The primary SAR of compounds show that, the substitution of either position 6 or position 8 on A ring of chrysin may be contribute to their activity of inhibition of PGE 2 production 7 . Figure 1: Structure of some natural chrysin derivatives. From the knowledge, the aryl groups attached into the ring system of flavone contribute the enhancement of lipophile characteristics comparable to the polyhydroxyflavone. It may be lead to increase the in vivo bioactivity of chrysin because of their permeability through the skin and other biological membranes. To obtain some new flavone supporting for process of screening biological activities some arylchrysin analogues were synthesized and determined their physic-chemical characteristic. Herein, we report the processes for synthesis of some arylchrysin derivatives by Suzuki reaction 8 via 8-iodochrysin or 8-bromochrysin as starting materials....
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This note was uploaded on 02/17/2011 for the course CHEMISTRY 101 taught by Professor Csr during the Spring '11 term at University of Louisville.

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