Ring expansion of 2-benzylidenecoumaran-3-ones—a synthesis of flavones

Fitzgerald, Danielle M.; O'Sullivan, J; Philbin, E. M.; Wheeler, T. S.

doi:10.1039/jr9550000860

Cited by 25 publications

(12 citation statements)

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“…Among the 14 compounds, 6 , 9 , 13 , and 14 were novel. The 1 H NMR data of four derivatives 2 , 8 , 10 , and 12 , the 13 C NMR data of two derivatives 7 and 11 , and both the 1 H and 13 C NMR data of derivative 1 have been previously reported . However, NMR data for three derivatives 3 , 4 , and 5 have not yet been reported …”

Section: Resultsmentioning

confidence: 94%

Synthesis of methoxybenzoflavones and assignments of their NMR data

Hwang

Hyun

et al. 2012

Magnetic Reson in Chemistry

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A phytotoxic root exudate from Acroptilon repens was identified as 7,8-benzoflavone, an inhibitor of cytochrome P450 1A2 and activator of cytochrome P450 3A4. The synthetic 5,6-benzoflavone also is a potent phytotoxin. Six 7,8-benzoflavones and eight 5,6-benzoflavones were synthesized in this study. The NMR data for a few of these compounds have been previously reported; however, the NMR data for most of them have not been reported. For reference purposes, the complete NMR data for the 14 benzoflavones are described.

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Section: Resultsmentioning

confidence: 94%

Synthesis of methoxybenzoflavones and assignments of their NMR data

Hwang

Hyun

et al. 2012

Magnetic Reson in Chemistry

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“…Direct isomerization of aurones to flavones is known to occur in basic media and in the presence of KCN . Isomerization of 2 to 4 was not observed during the formation of 2 in the presence of NaH or pyridine.…”

Section: Resultsmentioning

confidence: 97%

“…Direct isomerization of aurones to flavones is known to occur in basic media and in the presence of KCN. 28 Isomerization of 2 to 4 was not observed during the formation of 2 in the presence of NaH or pyridine. However, treatment of isolated 2a with KO t Bu in EtOH slowly yielded the flavone 4a along with decomposition products.…”

Section: ' Results and Discussionmentioning

confidence: 98%

Synthesis and Structural Characterization of Ferrocenyl-Substituted Aurones, Flavones, and Flavonols

et al. 2011

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In the context of our studies on the modification of bioactive molecules with ferrocene, we here report the first examples of ferrocenyl flavonoids, where ferrocene replaces the B ring of the flavonoid skeleton. Ferrocenyl aurones possessing an electron-withdrawing or an electron-donating group in the 5′-position were obtained from 5′-R-2′-hydroxy-3-ferrocenyl chalcones via 1,5 oxidative exocyclization using Hg(OAc)2 or AgOTf. Treatment of the ferrocenyl aurones with LDA resulted in a ring opening to form ferrocenyl ynones, which could then be selectively recyclized to the flavone isomer by treatment with NaOEt. Ferrocenyl flavones were also obtained by isomerization of the aurones with KCN and were hydroxylated in the 3-position to form ferrocenyl flavonols with oxone in a biphasic reaction. In many cases the reactivity of the ferrocenyl compounds was significantly different from that of their organic analogues. This reactivity and regioselectivity can be rationalized by ferrocene’s particular ability to destabilize α-anions in reaction intermediates. Representative examples of ferrocenyl aurones, ynones, and flavones were characterized by 2D NMR and X-ray crystallography, and the molecules all show a planar arrangement of the organic skeleton with the cyclopentadienyl ring of the ferrocene group. Putative MLCT bands in the visible region are responsible for the variety of highly saturated colors observed.

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“…Chem. 1956, benzene/petroleum 168-169 (170) (10) white needles OCHg H CHg Cl7H160g 2.45 (s, 3 H, -CHg), 3.9 (s, 3 H, ether -OCHg), 6.7 (s, 1 , H-3), 7.6 (m, 7 H, aromatic) 8e benzene / petroleum 181-182 (179) (11) white crystals H Br CHg ^ie^n^rU2 (12) white needles OCHg H CHg Ci7H1603Br…”

Section: Literature Citedmentioning

confidence: 99%