Reaction of azulenes with 1-trifluoromethanesulfonylpyridinium trifluoromethanesulfonate (TPT) and synthesis of the parent azulene

Ito, Shunji; Yokoyama, Ryuji; Okujima, Tetsuo; Terazono, Tomomi; Kubo, Takaya; Tajiri, Akio; Watanabe, Masataka; Morita, Noboru

doi:10.1039/b212484j

Cited by 20 publications

(10 citation statements)

References 27 publications

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“…In contrast, when the reaction was carried out with a large excess of pyridine, it gave 1,3-bis(dihydropyridin-4-yl)azulene, the product of the attack of azulene on TPT selectively at the 4-position. [9] As in the case of the reaction between azulene and TPT, the proportions of azulene, Tf 2 O, and pyridine are very important in determining the product distribution. Treatment of 1 with TPT in the presence of excess pyridine gave 6 in 88 % yield, along with 7 in 5 % yield.…”

Section: Resultsmentioning

confidence: 99%

Electrophilic ipso‐Substitution and Some Unique Reaction Behavior of 1,3,6‐Tri‐tert‐butylazulene

et al. 2009

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Electrophilic ipso‐substitution reactions between 1,3,6‐tri‐tert‐butylazulene (2) and several electrophilic reagents were examined. Friedel–Crafts and Vilsmeier reactions of 2 gave the corresponding ipso‐substitution products in moderate to excellent yields. One of the ipso‐substitution products, 1,6‐di‐tert‐butyl‐3‐formylazulene (5), was converted in high yield into the synthetically more useful azulene derivative 1,6‐di‐tert‐butylazulene (1) by decarbonylation on treatment with pyrrole in acetic acid. Treatment of 2 with N‐[(trifluoromethyl)sulfonyl]pyridinium trifluoromethanesulfonate (TPT) unexpectedly afforded 1‐trifluoromethylthioazulene 10 and 1(8H)‐azulenone 11. Compound 2 also reacted with tetracyanoethylene (TCNE) to give an excellent yield of cycloaddition product 13, rather than the ipso‐substitution reaction product.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

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Section: Resultsmentioning

confidence: 99%

Electrophilic ipso‐Substitution and Some Unique Reaction Behavior of 1,3,6‐Tri‐tert‐butylazulene

et al. 2009

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“…33 Although a method for the high-yielding preparation of triflate 36 from alcohol 35 using Tf 2 O and triethylamine was finally established, 34 we realized the pathway leading to 37 might be applicable to the preparation of nitrogen-containing 1-heteroaryl-and 1,3-diheteroarylazulenes.…”

Section: Electrophilic Heteroarylation At the 1-and 3-positionsmentioning

confidence: 99%

Recent Advances in the Development of Methods for the Preparation of Functionalized Azulenes for Electrochromic Applications

Ito¹,

Shoji²,

Morita³

2011

Synlett

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Recent advances made in the preparation of aryl-and heteroarylazulenes using transition-metal-catalyzed reactions and azulene electrophilic heteroarylation reactions are described. Emphasis is given to the development of novel azulenyl-substituted metallic reagents. The synthetic routes that utilize these processes as key steps provide straightforward access to functionalized azulene-based advanced materials that possess unique redox properties.

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“…Previously, we have reported the reaction of azulene with pyridine in the presence of Tf 2 O to afford 1,3-bis(dihydro-4-pyridyl)azulene in good yield. [15] If the dihydropyridine moieties could be converted into pyridyl groups, a practical synthetic procedure for the preparation of pyridylazulenes by electrophilic substitution reaction could be established.…”

Section: ·2imentioning

confidence: 99%

“…Therefore, presence of excess pyridine is a key to induce the attack of 1a on TPT at the 4-position to afford the 1,3-bis(dihydro-4-pyridyl)azulene derivative in good yield. [15] Thus, the reaction of 1a was carried out by using 1.2 equiv. of Tf 2 O in the presence of excess pyridine to afford 2a in 72 % yield, along with 3a in 10 % yield (Scheme 1).…”

Section: ·2imentioning

confidence: 99%

Synthesis of 1‐Heteroaryl‐ and 1,3‐Bis(heteroaryl)azulenes: Electrophilic Heteroarylation of Azulenes with the Triflates of N‐Containing Heteroarenes

et al. 2011

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An efficient synthesis of 1‐heteroaryl‐ and 1,3‐bis(heteroaryl)azulenes was established by electrophilic substitution. The reaction of azulenes and 1,1′‐biazulene with the triflate of N‐containing heteroarenes proceeded smoothly in the presence of excess heteroarenes to afford the corresponding 1‐dihydroheteroaryl‐ and 1,3‐bis(dihydroheteroaryl)azulene derivatives in good yields. The 1‐dihydroheteroaryl‐ and 1,3‐bis(dihydroheteroaryl)azulene derivatives were readily converted into the desired 1‐heteroaryl‐ and 1,3‐bis(heteroaryl)azulenes by treatment with tBuOK in DMSO or KOH in EtOH in excellent yields. The pyridinium salts 26+·I– and 272+·2I– were also prepared by the reaction of 4a and 5a with methyl iodide. 1‐Heteroaryl‐ and 1,3‐bis(heteroaryl)azulenes exhibited a significant color change in acetic acid from that in dichloromethane due to the development of intramolecular charge‐transfer (CT) absorption bands.

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Reaction of azulenes with 1-trifluoromethanesulfonylpyridinium trifluoromethanesulfonate (TPT) and synthesis of the parent azulene

Cited by 20 publications

References 27 publications

Electrophilic ipso‐Substitution and Some Unique Reaction Behavior of 1,3,6‐Tri‐tert‐butylazulene

Electrophilic ipso‐Substitution and Some Unique Reaction Behavior of 1,3,6‐Tri‐tert‐butylazulene

Recent Advances in the Development of Methods for the Preparation of Functionalized Azulenes for Electrochromic Applications

Synthesis of 1‐Heteroaryl‐ and 1,3‐Bis(heteroaryl)azulenes: Electrophilic Heteroarylation of Azulenes with the Triflates of N‐Containing Heteroarenes

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