- Synthetic Utility and Mechanistic Implications of the Fries Rearrangement of Hydroquinone Diesters in Boron Trifluoride Complexes
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Reactions of boron trifluoride methyl and ethyl etherate complexes with hydroquinone diesters yield monomethyl and monoethyl derivatives of acetylhydroquinones. The use of sterically hindered boron trifluoride etherate complexes results in acetylhydroquinone derivatives. This procedure represents a one-step synthesis of acetylhydroquinone derivatives, important building blocks for a variety of synthetic applications.
- Boyer, Jessica L.,Krum, Jodie E.,Myers, Michael C.,Fazal, Aleem N.,Wigal, Carl T.
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- Anti-tyrosinase, antioxidant, and antibacterial activities of novel 5-hydroxy-4-acetyl-2,3-dihydronaphtho[1,2- b ]furans
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Novel 5-hydroxy-4-acetyl-2,3-dihydronaphtho[1,2-b]furans (7a-k) were synthesized using ceric ammonium nitrate (CAN)-catalyzed formal [3 + 2] cycloaddition. Synthesized compounds were evaluated for their tyrosinase inhibitory, antioxidant, and antibacterial activities. A modified spectrophotometric method using l-DOPA as substrate was used to determine tyrosinase inhibitory activities, and a 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay was used to evaluate antioxidant properties. Antibacterial activities against gram-negative Escherichia coli (KCTC-1924) and gram-positive Staphylococcus aureus (KCTC-1916) were evaluated using the disc diffusion technique. Of the synthesized compounds, 7b with a 4-acetyl and an electron-enriched dihydronaphthofuran ring showed the highest tyrosinase-inhibition activity (IC50 Combining double low line 8.91 μg/mL), which was comparable with that of standard kojic acid (IC50 Combining double low line 10.16 μg/mL), potent antioxidant activity (IC50 Combining double low line 3.33 μg/mL), which was comparable with that of BHT (IC50 Combining double low line 34.67 μg/mL), and excellent antibacterial activities (MICs: 0.50 μg/mL against E. coli and S. aureus strains). A mechanistic analysis of 7b demonstrated that its tyrosinase inhibitory activity was reversible and competitive. Compounds 7c and 7d showed potent antioxidant activities (IC50: 6.30 and 5.01 μg/mL), and compound 7d also exhibited potent inhibitory activity against E. coli with a MIC of 0.5 μg/mL. Furthermore, compounds 7a, 7e, 7f, and 7i showed potent antibacterial activities against S. aureus with MICs of 0.5 μg/mL, which was comparable to that of ampicillin (MIC Combining double low line 0.5 μg/mL).
- Xia, Likai,Idhayadhulla, Akber,Lee, Yong Rok,Wee, Young-Jung,Kim, Sung Hong
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p. 605 - 612
(2015/01/16)
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