2015
DOI: 10.5155/eurjchem.6.3.305-313.1268
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Abstract: We describe the oxidation of flavanones by employing phenyliodonium diacetate to form the flavone (15), isoflavone (8) and 2,3-dihydrobenzofurane (18) in this study. The oxidative method was found to be regioselective and dependent on the substitution pattern present on the two aromatic rings of the starting flavanone. The structures of products obtained were fully characterized by using IR, 1 H and 13 C NMR spectroscopy and Mass spectrometry. X-ray crystallography further confirms the structures of flavones a… Show more

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Cited by 6 publications
(5 citation statements)
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References 36 publications
(38 reference statements)
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“…In a more recent publication identical conditions (PIDA as an oxidant, TMOF as a solvent, and H 2 SO 4 as a catalyst) were applied to three flavanones with slightly different substitution patterns. Interestingly, a different yet selective outcome was reported for all three cases: while one flavanone was reported to react selectively to the expected benzofuran by ring contraction, the other two underwent oxidation to the flavone or oxidative 2,3-aryl migration to the isoflavone, respectively . When we applied these conditions to our test substrate 18 , only the isoflavone 21 and its flavone isomer 23 were isolated in comparable yields (entry 10).…”
Section: Resultsmentioning
confidence: 83%
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“…In a more recent publication identical conditions (PIDA as an oxidant, TMOF as a solvent, and H 2 SO 4 as a catalyst) were applied to three flavanones with slightly different substitution patterns. Interestingly, a different yet selective outcome was reported for all three cases: while one flavanone was reported to react selectively to the expected benzofuran by ring contraction, the other two underwent oxidation to the flavone or oxidative 2,3-aryl migration to the isoflavone, respectively . When we applied these conditions to our test substrate 18 , only the isoflavone 21 and its flavone isomer 23 were isolated in comparable yields (entry 10).…”
Section: Resultsmentioning
confidence: 83%
“…Interestingly, a different yet selective outcome was reported for all three cases: while one flavanone was reported to react selectively to the expected benzofuran by ring contraction, the other two underwent oxidation to the flavone or oxidative 2,3-aryl migration to the isoflavone, respectively. 54 When we applied these conditions to our test substrate 18, only the isoflavone 21 and its flavone isomer 23 were isolated in comparable yields (entry 10). With PIFA an improved selectivity toward the oxidative 2,3-aryl migration pathway was observed and a mixture of MOM-protected isoflavone 21 and deprotected isoflavone 22 was obtained in an overall yield of 42% (entry 11).…”
Section: ■ Introductionmentioning
confidence: 99%
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“…In this synthesis the prenyl substituent was introduced after the oxidative rearrangement through a Pd-catalyzed coupling . One reason for the restricted utilization of the oxidative rearrangement method could be the confusing and sometimes contradictory literature precedence: isoflavones, flavones, and benzofurans or mixtures of these products have been reported to arise from the reaction of flavanones with hypervalent iodine reagents. A plausible mechanism for the formation of all three types of products is shown in Scheme for the reaction of an unsubstituted flavanone A with the hypervalent iodine reagent [bis­(trifluoroacetoxy)­iodo]­benzene (BTI). , The initial step is an electrophilic iodination of A at C-3 that presumably proceeds via the enol B . The 3-iodinated product C is the central intermediate for all possible products: isoflavones are formed via migration of the C-2-aryl substituent with intramolecular substitution of the iodo substituent and deprotonation at C-3 (black arrows), flavones result from β-elimination (blue arrow), and benzofurans result from a ring contraction (red arrow) and nucleophilic trapping of the oxocarbocation ( G ) with MeOH.…”
mentioning
confidence: 99%
“…Based on the physiological properties related to physical attractiveness of the plants and also their promising role in the health sector for humans, various efforts have been made both to isolate flavanone compounds from plants and to carry out synthesis in the laboratory. In the laboratory, the synthesis of flavanones from the chalcone precursor with the formation of unsubstituted flavanone from 2'-hydroxychalcone could be occured with the help of catalysts such as mineral, ion-exchange resins, and acetic acids [5][6][7].…”
Section: Introductionmentioning
confidence: 99%