New Syntheses of Flavones from Diels–Alder Reactions of 2-Styrylchromones withortho-Benzoquinodimethanes

Silva, Artur M. S.; Silva, Ana M. G.; Tomé, Augusto C.; Cavaleiro, José A. S.

doi:10.1002/(sici)1099-0690(199901)1999:1<135::aid-ejoc135>3.0.co;2-i

Cited by 23 publications

(7 citation statements)

References 25 publications

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“…As far as we are aware only one paper was published on this subject. 44 2-Styrylchromones 37 reacted with ortho-benzoquinodimethane 51 (highly reactive diene generated in situ by thermal extrusion of SO 2 from sulfone 50) to give chromones 52 (Scheme 12). In some cases, when there was no substitution at C-α of 2-styrylchromones 37 (R = H), the obtained cycloadducts 52 could be dehydrogenated into 2-[2-(3-arylnaphthyl)]chromones 53, novel benzoflavone-type compounds.…”

Section: 2styrylchromones As Dienophilessupporting

confidence: 81%

Synthesis and reactivity of styrylchromones

Silva¹,

Pinto²,

Cavaleiro³

et al. 2004

Arkivoc

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2-Styrylchromones, although scarce in nature, constitute a group of oxygen heterocyclic compounds which have shown significant biological activities. Their transformation and the transformation of their 3-isoanalogues into other biologically active compounds have been exploited. This short review describes the most recent work on the synthesis, biological evaluation and transformation of 2-and 3-styrylchromones.

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Section: 2styrylchromones As Dienophilessupporting

confidence: 81%

Synthesis and reactivity of styrylchromones

Silva¹,

Pinto²,

Cavaleiro³

et al. 2004

Arkivoc

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“…Complete aromatization of 1,2,3,4-tetrahydronaphthylchromone 67 (R 1 , R 3 = H, R 2 = Me) derived from 2-(α-methylstyryl)chromone was not possible; instead, 2-(2-methyl-3-phenyl-1,2-dihydronaphth-2-yl)]chromone 71 was isolated in 78 % yield. [99] Years later, Silva's group extended the study to reactions between o-benzoquinodimethane (66) and 2-SCs substituted at C-5. The corresponding 1,2,3,4-tetrahydronaphthylchromones 67 (R 1 = OH) were prepared in lower yields (62-63 %).…”

Section: Cycloadditionmentioning

confidence: 98%

“…[98] Acting as dienophiles, a series of 2-SCs reacted with excess quantities of highly reactive o-benzoquinodimethane (66, formed in situ by the thermal extrusion of sulfur dioxide from 1,3-dihydrobenzo[c]thiophene 2,2-dioxide) in 1,2,4-trichlorobenzene at reflux to provide 2-(3-aryl-1,2,3,4-tetrahydronaphth-2-yl)]chromones 67 (R 1 = H) in 76-89 % yields (Scheme 17). [99] Complete aromatization of the obtained cycloadducts was achieved by a two-step approach involving benzylic bromination with NBS in the presence of benzoyl peroxide and subse-also obtained and easily converted into the desired naphthylchromones 68 (R 1 = H) by treatment with ammonium formate and Pd/C in methanol at reflux.…”

Section: Cycloadditionmentioning

confidence: 99%

An Overview of 2‐Styrylchromones: Natural Occurrence, Synthesis, Reactivity and Biological Properties

Santos

Silva

2017

Eur J Org Chem

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“…To the best of our knowledge, the use of 2-styrylchromones as dienophiles in Diels-Alder reactions has only been reported by us in a couple of papers involving the symmetric ortho-benzoquinodimethane. 15,16 This extremely reactive diene was used in the synthesis of a large number of naphthylchromones and constitutes a versatile intermediate in other cycloaddition reactions. 17 Much less attention has been given to the chemistry of heteroaromatic analogues of ortho-quinodimethanes.…”

Section: 4mentioning

confidence: 99%

“…26 Recently we have reported the synthesis of novel flavone derivatives from the Diels-Alder reaction of (E)-2-styrylchromones with the symmetric ortho-benzoquinomethane. 15,16 The good results obtained led us to extend that work to the Diels-Alder reaction of (E)-2-styrylchromones 1a-h 27 with the asymmetric pyrimidine ortho-quinodimethane 2 (Scheme 1). This reactive diene was generated in situ by thermal extrusion of sulfur dioxide from the corresponding sulfone 4-methoxy-2-methyl-5,7-dihydrothieno [3,4-d]pyrimidine 6,6-dioxide.…”

Section: Introductionmentioning

confidence: 99%

Tetrahydroquinazoline-substituted chromones from Diels–Alder reaction of (E)-2-styrylchromones and pyrimidine ortho-quinodimethane

Patoilo

Silva

Pinto

et al. 2012

Tetrahedron Letters

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a b s t r a c tThe Diels-Alder reaction of (E)-2-styrylchromones with a pyrimidine ortho-quinodimethane is reported for the first time. These cycloaddition reactions afford mixtures of two regioisomeric tetrahydroquinazoline-substituted chromones in moderate to excellent global yields. Irrespective of the substituents on the 2-styrylchromones, the 2-(7-aryl-4-methoxy-2-methyl-5,6,7,8-tetrahydroquinazolin-6-yl)chromone derivatives are always the major isomers.Ó 2012 Elsevier Ltd. All rights reserved.2-Styrylchromones are a small group of naturally-occurring heterocyclic compounds. Since the isolation of the first natural 2-styrylchromone in 1986, 1 that showed to be a potent cytotoxic agent, a large number of publications have emerged involving the synthesis and transformation of this type of chromone derivatives. 2,3 A literature survey revealed that 2-styrylchromones have been typically prepared from ortho-hydroxyacetophenones where the aldol condensation/oxidative cyclization and the BakerVenkataraman methods are the most promising approaches for the synthesis of a large variety of derivatives. As a result, a series of styrylchromone analogues were synthesized and several biological properties have been assigned to them, including antiallergic, antioxidant, antifungal, anti-inflammatory, and antitumor activities. 3,4Besides the synthesis, studies on the reactivity of 2-styryl chromones and their use as synthons in the preparation of other important classes of compounds have been highlighted in the literature. Most important is their reaction with hydrazines to afford several pyrazole derivatives 5,6 and also their interception in pericyclic reactions as dienes, dienophiles, and also as dipolarophiles. In the former case, the synthesis of several xanthone-type compounds was performed by cycloaddition reaction with maleic anhydride, N-arylmaleimides, and cyclic and acyclic enamines. [7][8][9][10][11] The reactions of these vinylchromones with diazomethane 12 and sodium azide 13,14 are the examples of their use as dipolarophiles to prepare 2-pyrazolines and 1,2,3-triazoles, respectively. To the best of our knowledge, the use of 2-styrylchromones as dienophiles in Diels-Alder reactions has only been reported by us in a couple of papers involving the symmetric ortho-benzoquinodimethane. 15,16 This extremely reactive diene was used in the synthesis of a large number of naphthylchromones and constitutes a versatile intermediate in other cycloaddition reactions. 17 Much less attention has been given to the chemistry of heteroaromatic analogues of ortho-quinodimethanes. The multi-step route, moderate yields, and a large number of secondary products are the limitations in the use of dienes in the preparation of these intermediates. [17][18][19] However, heterocyclic ortho-quinodimethanes are an attractive tool in the design of novel heteropolycyclic compounds. Following our interest on the chemistry of ortho-quino dimethanes [20][21][22][23] and on the synthesis of heterocyclic compounds, we decided to study the Diels-A...

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New Syntheses of Flavones from Diels–Alder Reactions of 2-Styrylchromones withortho-Benzoquinodimethanes

Cited by 23 publications

References 25 publications

Synthesis and reactivity of styrylchromones

Synthesis and reactivity of styrylchromones

An Overview of 2‐Styrylchromones: Natural Occurrence, Synthesis, Reactivity and Biological Properties

Tetrahydroquinazoline-substituted chromones from Diels–Alder reaction of (E)-2-styrylchromones and pyrimidine ortho-quinodimethane

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