Improved protocol for the synthesis of functionalized triphenylene ketals

Waldvogel, Siegfried R.; Mirk, Daniela

doi:10.1016/s0040-4039(00)00722-x

Cited by 31 publications

(15 citation statements)

References 2 publications

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“…[10] Triphenylene ketals represent triketals of 2,3,6,7,10,11-hexahydroxytriphenylene and can be synthesized by oxidative trimerization of the corresponding catechol ketals, employing MoCl 5 [11] or anodic protocols. [12,13] If functionalized benzoA C H T U N G T R E N N U N G [1,3]dioxols are subjected to these methods, the statistical mixture is produced, yielding more than 75 % of the undesired stereoisomer. A repetitive sequence of isomer separation and isomerization under strong acidic conditions allows the formation of larger quantities of the all-syn functionalized triphenylene ketal.…”

Section: Introductionmentioning

confidence: 99%

Stereoselective Formation of Triphenylene Ketals

Boshta

Bomkamp

Schnakenburg

et al. 2010

Chemistry A European J

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The oxidative trimerization of catechol ketals by MoCl(5) or MoCl(5)/TiCl(4) mixtures leads preferentially to the all-syn stereoisomer of the corresponding triphenylene ketal. The concomitant metal salts of the oxidative coupling most probably form a multinuclear template that directs the diastereoselectivity in a subsequent isomerization step under electrophilic conditions. Several functionalities can serve as coordination sites for the multinuclear metal chloro clusters. Suitable functional groups have to be stable towards the strong electrophilic and oxidizing conditions. Therefore, esters, nitriles, nitro derivatives, triazoles, and pyridines are successfully employed. Based on the flexibility and size of the substrate, different reagent mixtures lead to the stereoselective formation of the all-syn derivatives.

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Section: Introductionmentioning

confidence: 99%

Stereoselective Formation of Triphenylene Ketals

Boshta

Bomkamp

Schnakenburg

et al. 2010

Chemistry A European J

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“…[29] A synthesis on large scales would consequently give significant amounts of molybdenum waste, but this might be avoidable by use of an anodic procedure. [30] Electrochemical trimerization could be performed easily even on a 20 g scale and provided the two isomeric triphenylene ketals in an almost statistical ratio. The unusually high yields for this transformation are a consequence of the low solubilities of the formed triphenylene ketals.…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Rigid Receptors Based on Triphenylene Ketals

et al. 2005

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The synthesis of rigid receptors based on triphenylene ketals, including some improved procedures, is described in detail. Since chemical transformations are strongly influenced by the rigid character and steric bulkiness of the receptors, the construction of a subunit allowing quicker synthetic development is also reported. The preparation of these receptor structures involves an oxidative trimerization and a subsequent repeated isomerization procedure. The scope for the attachment of sterically demanding affinity groups on the receptor scaffold and the corresponding subunit is discussed, and the molecular structures and available space for molecular recognition of the chirally modified systems are outlined by some crystal structures. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

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“…Typically, the oxidative trimerization of catechol derivatives can be induced by metal salts in high oxidation states, for example by molybdenum pentachloride [4,10]. Electrochemical methods can be applied to realize the oxidative trimerization since the formation of metal waste is avoided [11–12]. Furthermore, no transition metal cations, which promote the cleavage of the ketal moiety [11], are involved.…”

Section: Introductionmentioning

confidence: 99%

“…Electrochemical methods can be applied to realize the oxidative trimerization since the formation of metal waste is avoided [11–12]. Furthermore, no transition metal cations, which promote the cleavage of the ketal moiety [11], are involved.…”

Section: Introductionmentioning

confidence: 99%

“…Usually, yields are in a moderate range (≤35%) [15] when the electrolysis is performed on platinum or graphite anodes in anhydrous and non-nucleophilic electrolytes [14]. Poor yields are caused by the low oxidation potential of the products and the preference for over-oxidation followed by decomposition of the generated radical cations [11,16]. …”

Section: Introductionmentioning

confidence: 99%

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Efficient electroorganic synthesis of 2,3,6,7,10,11-hexahydroxytriphenylene derivatives

Regenbrecht¹,

Waldvogel²

2012

Beilstein J. Org. Chem.

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Summary2,3,6,7,10,11-Hexahydroxytriphenylene of good quality and purity can be obtained via anodic treatment of catechol ketals and subsequent acidic hydrolysis. The electrolysis is conducted in propylene carbonate circumventing toxic and expensive acetonitrile. The protocol is simple to perform and superior to other chemical or electrochemical methods. The key of the method is based on the low solubility of the anodically trimerized product. The shift of potentials is supported by cyclic voltammetry studies.

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Improved protocol for the synthesis of functionalized triphenylene ketals

Cited by 31 publications

References 2 publications

Stereoselective Formation of Triphenylene Ketals

Stereoselective Formation of Triphenylene Ketals

Synthesis of Rigid Receptors Based on Triphenylene Ketals

Efficient electroorganic synthesis of 2,3,6,7,10,11-hexahydroxytriphenylene derivatives

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