290. The constitution of oroxylin-A. Part II. Attempted synthesis of oroxylin-A and the synthesis of wogonin

Shah, Rahul; Mehta, C. R.; Wheeler, T. S.

doi:10.1039/jr9380001555

Cited by 30 publications

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“…The crude product was recrystallized from aqueous methanol (3:1) to give 9 as a pale yellow solid (7.3 g, 95%), mp 287-288 • C, lit. 12 …”

Section: -Hydroxy-58-dimethoxy-2-phenyl-4h-chromen-4-one (9)mentioning

confidence: 97%

“…Suan et al reported that 9 could be obtained from 7 by two steps: firstly acetylating and then reacting with sodium benzoate and benzoic anhydride. 12 Additionally, Rivaille et al 13 reported that 9 could be obtained directly by cyclization of compound 7 with acetyl benzoylacetate. However, both of these methods have many drawbacks such as poor yields, high reaction temperature and long reaction time, all of which made these approaches unsuitable for scale up.…”

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confidence: 99%

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Convenient Synthesis of Wogonin, A Flavonoid Natural Product with Extensive Pharmacological Activity

Li¹,

Cao²,

Wang³

et al. 2009

Organic Preparations and Procedures International

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Wogonin (5,7-dihydroxy-8-methoxyflavone, 5), a flavonoid natural product first isolated from Scutellaria Radix, is well-known for its anti-inflammation, 1 anti-allergy, 2 anti-tumor 3 and anti-hepatitis B virus 4 properties. Owing to its extensive applications in medical treatment, researchers have developed several synthetic pathways to obtain this important natural product since the early part of the last century. 5, 6 The initial total syntheses of wogonin were based on the common synthetic approaches to flavonoids through Baker-Venkataraman rearrangement 6, 7 or intramolecular Wittig reaction. 8 However, neither of these two strategies was efficient for large scale production of the compound. Recently Huang et al. 9 reported a simplified synthesis of wogonin (5) and oroxylin A (6) from 3,4,5-trimethoxyphenol (1) and cinnamoyl chloride (2). As shown in Figure 1, the flavone nucleus was obtained from intermediate 4 wherein the two hydroxyl groups compete for the addition to the α,β-unsaturated ketone moiety. Evidently, the C 6 -OH is more active than C 2 -OH since the yield of oroxylin A was nearly double that of wogonin. Moreover, this synthetic route is not an ideal process for industrial production because the two products are difficult to separate.Prompted by this earlier report on the construction of the flavone nucleus, we launched our own studies, focusing on avoiding the undesired flavone derivative 6 in the total synthesis of pure wogonin (Figure 2). To avoid the competitive addition process while forming the flavone nucleus, we utilized intermediate 8 which has only one reactive position. Intermediate 8 was synthesized in >90% yield from 2,5-dimethoxybenzene-1,3-diol (7)

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“…The crude product was recrystallized from aqueous methanol (3:1) to give 9 as a pale yellow solid (7.3 g, 95%), mp 287-288 • C, lit. 12 …”

Section: -Hydroxy-58-dimethoxy-2-phenyl-4h-chromen-4-one (9)mentioning

confidence: 97%

mentioning

confidence: 99%

Convenient Synthesis of Wogonin, A Flavonoid Natural Product with Extensive Pharmacological Activity

Li¹,

Cao²,

Wang³

et al. 2009

Organic Preparations and Procedures International

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The Acylation of Ketones to Form β‐Diketones or β‐Keto Aldehydes

2011

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Under certain conditions, a ketone having an alpha‐hydrogen atom may be acylated with an ester, an acid anhydride, or an acid chloride to form a β‐ketone or, when the acylating agent is a formic ester, a β‐keto aldehyde. The process consists in the replacement of an alpha‐hydrogen atom of the ketone by an acyl group. The reaction involves a carbon‐carbon condensation. The acylation of ketones with esters has generally been effected by means of a basic reagent, such as sodium, sodium ethoxide, etc. The acylation of ketones to form β‐diketones may also occur with acid anhydrides by means of an acidic reagent boron trifluoride. In this chapter the basic reagent and boron trifluoride methods of acylation are considered separately. They are compared with other methods.

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Potentiell antianaphylaktische 5′‐ und 6‐Carboxyflavonderivate

Wurm

Geres

1977

Archiv der Pharmazie

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In Analogie zu antiallergisch aktiven ZCarboxyxanthonderivaten wurden als Strukturvenvandte 2'-Hydroxy-6-carboxyflavon mit planarer Orientierung des Arylrestes in 2-Stellung und der Methylather mit nicht planarer Anordnung des Arylrestes sowie die stlukturisomeren 4'-Hydroxyund 4'-Methoxyderivate als po tentiell antianaphylaktische Substanzen synthetisiert. Aus 2'-Hydroxyd-carboxyflavon entsteht durch Wessely-Moser-Umlagerung 2'-Hydroxy-5'-carboxyflavon.Potential Antianaphylactics: 5'and 6-Carboxyflavone Derivatives 2Carboxyxanthone derivatives have antiallergic properties. Hence 2'-hydroxy-6-carboxyflavone with planar orientation of the 2-aryl group, its methyl ether without planar orientation of this group and the 4'-hydroxy and 4'-methoxy isomers were synthesized as potentially antianaphylactic analogs. 2'-Hydroxy-6-carboxyflavone gives 2'-hydroxy-5'-carboxyflavone by Wessely-Moser rearrangement.Seit der Einfuhrung von Dmatriumcromoglicicum') -das ein neues Wirkprinzip durch Stabilisierung der Mastzellenmembran2) in der Behandlung allergischer Reaktionen darstelltin die Therapie wurden zahlreiche Substanzen synthetisiert, die i m PCA (passive cutanous anaphylaxis) -Test haufig wesentlich wirksamer als die Standardsubstanz sind. Hierbei handelt es sich um Carbonsauren von Benzo4-pyronen und ihre N -H e t e r~a n a l o g e n~~~~'~) .Als besonders wirksam erwiesen sich 2Carboxyxanthon-derivate3) (A in Abb. 1) und da auch 5,6,7-Trihydroxyflavon PCA-Aktivitat be-Teilweise vorgetragen anlalich der Hauptversammlung der Deutschen Pharmazeutischen Gesellschaft in Miinchen 1975.

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290. The constitution of oroxylin-A. Part II. Attempted synthesis of oroxylin-A and the synthesis of wogonin

Cited by 30 publications

References 0 publications

Convenient Synthesis of Wogonin, A Flavonoid Natural Product with Extensive Pharmacological Activity

Convenient Synthesis of Wogonin, A Flavonoid Natural Product with Extensive Pharmacological Activity

The Acylation of Ketones to Form β‐Diketones or β‐Keto Aldehydes

Potentiell antianaphylaktische 5′‐ und 6‐Carboxyflavonderivate

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