- Unified Approach to (Thio)chromenones via One-Pot Friedel-Crafts Acylation/Cyclization: Distinctive Mechanistic Pathways of β-Chlorovinyl Ketones
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A facile synthetic method to chromenones and thiochromenones has been developed using a one-pot Friedel-Crafts acylation of alkynes with suitably substituted benzoyl chlorides. This unified approach to (thio)chromenones is readily applicable to aryl- and alkylalkynes where the stereochemically well-defined β-chlorovinyl ketone intermediates undergo distinctively different cyclization pathways. The ready availability of both starting materials, alkynes and benzoyl chlorides, coupled with the experimental simplicity makes the current synthetic method to (thio)chromenones fast, efficient, and practical.
- Kim, Hun Young,Song, Eunsun,Oh, Kyungsoo
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supporting information
p. 312 - 315
(2017/04/21)
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- Synthesis of functionalized chromones via organocatalysis
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A facile and versatile organocatalytic approach to access 2-substituted and 2,3-disubstituted chromone derivatives under mild conditions was developed, which was effectively catalyzed by novel proline phenylsulphonylhydrazide or pyrrolidine. As a result, diversely functionalized chromones were obtained in up to 99% yield. In addition, further modification of the corresponding chromones afforded novel polycyclic chromones.
- Wen, Sai-Shuai,Wang, Jing,Luo, Yi-Ming,Yang, Hua
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p. 9314 - 9320
(2015/03/05)
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- Ruthenium-NHC-catalyzed asymmetric hydrogenation of flavones and chromones: General access to enantiomerically enriched flavanones, flavanols, chromanones, and chromanols
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Two to four! Readily available flavones and chromones were efficiently converted into four valuable chiral classes of O-heterocycles - flavanones, chromanones, flavanols, and chromanols - by means of an enantioselective Ru/NHC-catalyzed hydrogenation process (see scheme; NHC=N-heterocyclic carbene, PCC=pyridinium chlorochromate). Copyright
- Zhao, Dongbing,Beiring, Bernhard,Glorius, Frank
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supporting information
p. 8454 - 8458
(2013/09/02)
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- A 'one pot' synthesis of 2-aryl-4H-1-benzopyran-4-ones under coupled microwave phase transfer catalysis (PTC) and ultrasonic irradiation PTC
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(Chemical Equation Presented) A 'one pot' synthesis of 2-aryl-4H-1- benzopyran-4-ones (3a-3f) is being reported. A mixture of o-hydroxyacetophenone, aroyl chloride, powdered n-tetrabutylammonium hydrogensulphate (n-TBAHSO 4) and potassium hydroxide (KOH) were either irradiated by microwaves or sonicated in an ultrasonic cleaning bath to afford flavones directly. On the contrary, conventional liquid-liquid Phase Transfer Catalysis (PTC) using benzene as organic phase and aqueous KOH as the second phase afforded first β-diketones in accordance with Baker-Venkataraman synthesis which upon cyclization by p-toluenesulphonic acid (p-TSA) gave desired flavones in the next step. PTC coupled with microwaves or ultrasound show enhanced yields, the clean reaction conditions require less time, and have easier workup protocol. All synthesized compounds were characterized by their Proton Magnetic Resonance (PMR), IR, FAB Mass and elemental analyses.
- Pathak, Vijai N.,Gupta, Ragini,Varshney, Bindu
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p. 589 - 592
(2008/09/19)
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- Photolysis of 3-bromochroman-4-ones
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Photolysis of 3-bromochroman-4-ones (1a-f) leads to debrominated chromanones (2a-f) and chromones (3a-f) as major products. Their formation is accounted for in terms of primary cleavage of the carbon halogen bond to give α-carbonyl radicals (I) and/or cations (II). In the case of the 2,2-disubstituted compounds (1d-f), intermediates (II) undergo rearrangement with 1,2-shift of the phenyl or benzyl substituent prior to deprotonation. Minor by-products are the pentacyclic pyrone (4e) or 2-methylchromone (3a) (starting from 1e and 1f, respectively).
- Consuelo Jiménez,Miranda, Miguel A.,Tormos, Rosa
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p. 339 - 347
(2007/10/03)
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- Synthesis and reactions of 2-benzylbenzopyran-4(H)-one and formation of xanthone derivatives
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2-Benzylbenzopyran-4(H)-one (I) has been synthesized by the reaction of the easily accessible o-hydroxyacetophenone with phenacyl chloride.Its reactivity towards electrophilic and nucleophilic reagents, cycloaddition reactions, and reactions with active methylene compounds leading to the formation of various products have been investigated.The structures of new compounds have been established with the help of IR and PMR spectral data.
- Mahmoud, M. R.,Amine, M. S.,Guirgius, D. B.
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p. 427 - 430
(2007/10/02)
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- CHROMONES FROM ACYLSALICYLIC ACIDS
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Acylsalicylic acids 1 can be converted by reaction with N-Phenylketeniminylidene triphenylphosphorane 2 into chromones 6 or 7.
- Bestmann, Hans Juergen,Schade, Gerold
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p. 997 - 998
(2007/10/02)
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