Synthetic Studies toward 5,6,7,3′,4′-Monomethoxytetrahydroxyflavones: Synthesis of Pedalitin
- Authors
- Kamma, Koteswara Rao; Cho, Joungmo; Won, Hyo Jun; Nam, So-Yeon; Le, Ngan Hong; Jung, Je Hyeong; Lee, Kee-In
- Issue Date
- 2024-01
- Publisher
- Multidisciplinary Digital Publishing Institute (MDPI)
- Citation
- Molecules, v.29, no.2
- Abstract
- During the synthetic studies toward 5,6,7,3 ',4 '-monomethoxytetrahydroxyflavones, a concise pedalitin synthesis procedure was achieved. As previously reported, 6-hydroxy-2,3,4-trimethoxyacetophenone was prepared by Friedel-Crafts acylation of 1,4-dihydroxy-2,6-dimethoxybenzene with boron trifluoride diethyl etherate in acetic acid. When aldol condensation of 6-hydroxy-2,3,4-trimethoxyacetophenone 2b with vanillin was performed in basic conditions, it produced 2 '-hydroxychalcone 3b, and, surprisingly, along with 3-hydroxyflavone 4 in a considerable amount. We propose that this oxidative cyclization is presumably due to the contribution of a quinone methide, likely to be subjected to aerobic oxidation. The chalcone was then subjected to oxidative cyclization with iodine in dimethyl sulfoxide to afford flavone 5 in good yield. To our delight, serial demethylation of the three methoxy groups at the 5-, 6-, and 3 '-positions of 5 proceeded smoothly to produce pedalitin 1, under hydrogen bromide solution (30% in acetic acid). The crystal structures of 3-hydroxyflavone 4 and pedalitin tetraacetate 6 were unambiguously determined by X-ray crystallography.
- Keywords
- HYDROXYLATED POLYMETHOXYFLAVONES; FLAVONOIDS; INHIBITORS; DEMETHYLATION; ANALOGS; 5,6,7,3 ' ,4 ' --monomethoxytetrahydroxyflavone; pedalitin; 2' -hydroxychalcone; 3-hydroxyflavone; aerobic oxidation; demethylation; X-ray crystal structure
- URI
- https://pubs.kist.re.kr/handle/201004/148596
- DOI
- 10.3390/molecules29020513
- Appears in Collections:
- KIST Article > 2024
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