104213-88-9Relevant articles and documents
Identification of the major degradation products of 4-methoxy-2-(3- phenyl-2-propynyl)phenol formed by exposure to air and light
Schiavi,Serafini,Italia,Villa,Fronza,Selva
, p. 812 - 814 (1992)
Exposure of 4-methoxy-2-(3-phenyl-2-propynyl)phenol (CO/1828) to air and light (accelerated by temperature) yields 1-(2-hydroxy-5-methoxyphenyl)-3- phenylpropynone as the major degradation product. With extraction, this product rapidly degrades to 5-methoxyaurone and 6-methoxyflavone. In addition, a mixture of dimeric and heterodimeric compounds that are not fully identified was observed. These results indicate the formation of a reactive ortho-quinone methide as an unstable intermediate. This hypothesis is supported by evidence that the aurone slowly isomerizes into the flavone in control samples. Identification of compounds was accomplished with mass spectrometry, nuclear magnetic resonance spectrometry, UV-high-performance liquid chromatography, and comparison with authentic samples.
One Pot Synthesis of γ-Benzopyranones via Iron-Catalyzed Aerobic Oxidation and Subsequent 4-Dimethylaminopyridine Catalyzed 6-endo Cyclization
Zhai, Di,Chen, Lingzhu,Jia, Minqiang,Ma, Shengming
supporting information, p. 153 - 160 (2017/11/23)
One-pot synthesis of γ-benzopyranones was realized in decent yields and excellent regioselectivities via iron-catalyzed aerobic oxidation and 4-dimethylaminopyridine-catalyzed cyclization of related propargylic alcohols. Derivatizations to aromatic substituted γ-benzopyranones and synthesis of naturally occurring 3′,4′-dimethoxyflavone have also been realized. (Figure presented.).
Synthesis of γ-benzopyranone by TfOH-promoted regioselective cyclization of o-alkynoylphenols
Yoshida, Masahito,Fujino, Yuta,Doi, Takayuki
supporting information; experimental part, p. 4526 - 4529 (2011/10/09)
Regioselective cyclization of o-alkynoylphenols forming γ-benzopyranones has been demonstrated. Trifluoromethanesulfonic acid (TfOH) induced 6-endo cyclization of o-alkynoylphenols without forming 5-exo cyclized benzofuranone derivatives to provide the corresponding γ-benzopyranones in high yields.
Regioselective synthesis of flavone derivatives via DMAP-catalyzed cyclization of o-alkynoylphenols
Yoshida, Masahito,Fujino, Yuta,Saito, Koya,Doi, Takayuki
experimental part, p. 9993 - 9997 (2012/02/06)
A catalytic amount of DMAP promoted cyclization of o-alkynoylphenols via a 6-endo cyclization mode leading to flavone derivatives in high yields without forming 5-exo cyclized aurone derivatives. Utilizing this method, methoxy substituted flavone and alkyl substituted γ-benzopyranone derivatives were synthesized.
6-Endo-Dig vs. 5-Exo-Dig Ring Closure in o-Hydroxyaryl Phenylethynyl Ketones. A New Approach to the Synthesis of Flavones and Aurones
Garcia, Hermenegildo,Iborra, Sara,Primo, Jaime,Miranda, Miguel A.
, p. 4432 - 4436 (2007/10/02)
The aryl phenylpropynoates 3a-c, prepared by esterification of phenylpropynoic acid with the corresponding phenols, by means of N,N'-dicyclohexylcarbodiimide, give upon irradiation the o-hydroxyaryl phenylethynyl ketones 4a-c.The cyclization of these compounds in basic media follows two alternative pathways: 6-endo-dig ring closure, to give the flavones 8a-c, and /or 5-exo-dig ring closure , to give the aurones 9a-c.The predominance of one or the other cyclization mode is strongly influenced by the reaction conditions.Thus, the use of potassium carbonate in acetoneas cyclizing reagent favors the 6-endo-dig process, while the 5-exo-dig process becomes clearly enhanced when using sodium ethoxide or potassium carbonate in ethanol.The mechanistic implications of these facts are discussed within the framework of Baldwin's rules.From the preparative point of view, the above results disclose the synthetic possibilities of the key ketones 4 as precursors of flavones and aurones.
