Proton nuclear magnetic resonance study of the addition of methoxide ion to 2,4,6-triphenylpyrylium, 2,4,6-triphenylthiopyrylium, 1,2,4,6-tetraphenylpyridinium and 1-(p-nitrophenyl)-2,4,6-triphenylpyridinium cations

Aveta, Raffaele; Doddi, Giancarlo; Insam, Normanno; Stegel, Franco

doi:10.1021/jo01313a027

Cited by 17 publications

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“…Die Protonen an den C-Atomen 3 und 5 geben sich als Singuletts bei 5,68-5,67 ppm bzw. 6,77-0,88 pprn zu erkennen; die fur 2a [5] angegebene Kopplung dieser Yrotonen (J = O,C, Hz) konnte bei ansonsten guter tfbereinstimmung der chemischen Verschiebung aller anderen Signale nicht beobachtet werden.…”

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Pyryliumverbindungen. 32 [1]. 2‐Methoxy‐2H‐thiopyrane aus 2,4,6‐Triaryl‐thiopyryliumsalzen

Zimmermann

Fischer

1986

J. Prakt. Chem.

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Pyrylium Compounds. 32. 2‐Methoxy‐2H‐thiopyrans from 2,4,6‐Triaryl‐thiopyrylium Salts Reaction of 2,4,6‐triarylthiopyrylium salts 1 with sodium methoxide in absolute methanol yields isolable 2‐methoxy‐2H‐thiopyrans 2, the structure of which was proved spectroscopically. Using the 2,4,6‐triphenyl derivative 2a as model compound, the behaviour of the 2‐methoxy‐2H‐thiopyran system towards some nucleophiles and electrophiles was studied. Thus, on heating with ethanol the 2‐ethoxy‐2H‐thiopyran 3 is formed. Nitromethane and ethyl cyanoacetate react with 2a in the presence of triethylamine to give 2,4,6‐triphenylbenzene (6) and 2,4,6‐triphenylbenzonitrile (7), respectively. Electrophiles (e. g. mineral acids or acyl halides) regenerate from 2a the starting thiopyrylium system; the same principle underlies the formation of 2,4,6‐triphenylthiopyrylium perchlorate (1a) and 2‐methoxy‐3‐methyl‐2,4,6‐triphenyl‐2H‐pyran (5) from 2a and 3‐methyl‐2,4,6‐triphenylpyrylium perchlorate (4).

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unclassified

Pyryliumverbindungen. 32 [1]. 2‐Methoxy‐2H‐thiopyrane aus 2,4,6‐Triaryl‐thiopyryliumsalzen

Zimmermann

Fischer

1986

J. Prakt. Chem.

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ChemInform Abstract: PROTON NUCLEAR MAGNETIC RESONANCE STUDY OF THE ADDITION OF METHOXIDE ION TO 2,4,6‐TRIPHENYLPYRYLIUM, 2,4,6‐TRIPHENYLTHIOPYRYLIUM, 1,2,4,6‐TETRAPHENYLPYRIDINIUM AND 1‐(P‐NITROPHENYL)‐2,4,6‐TRIPHENYLPYRIDINIUM CATIONS

Aveta¹,

Doddi²,

Insam³

et al. 1981

Chemischer Informationsdienst

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Pyryliumverbindungen. XVIII, 2‐Alkoxy‐2H‐pyrane aus tetra‐ und pentasubstituierten Pyryliumsalzen

1983

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Pyrylium Compounds. XVIII. 2‐Alkoxy‐2H‐pyrans from Tetra‐ and Pentasubstituted Pyrylium Salts Alkali alkoxides add regioselectively to 2,3,4,6‐tetrasubstituted pyrylium salts 7 (R' H), affording high yields of colourless crystalline 2‐alkoxy‐2H‐pyrans 9. The latte are also formed simply on refluxing 7 in the corresponding alcohol with triethylamine as proton acceptor. 3,5‐Dialkylsubstituted 2,4,6‐triarylpyrylium salts react analogously. The 2H‐pyran structure of the adducts obtained follows from their n.m.r., i.r., u.v. and mass spectra as well as from their reaction with tetracyanoethylene to cycloadducts of type 10. Acids regenerate from 9 the original pyrylium cations, whereas reaction of 9 with nitromethane or ethyl cyanoacetate provides benzene derivatives. ‐‐ The novel starting pyrylium salts 7b‐‐o are characterized by u.v./vis data and by transformation into the corresponding pyridine derivatives

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Proton nuclear magnetic resonance study of the addition of methoxide ion to 2,4,6-triphenylpyrylium, 2,4,6-triphenylthiopyrylium, 1,2,4,6-tetraphenylpyridinium and 1-(p-nitrophenyl)-2,4,6-triphenylpyridinium cations

Cited by 17 publications

References 1 publication

Pyryliumverbindungen. 32 [1]. 2‐Methoxy‐2H‐thiopyrane aus 2,4,6‐Triaryl‐thiopyryliumsalzen

Pyryliumverbindungen. 32 [1]. 2‐Methoxy‐2H‐thiopyrane aus 2,4,6‐Triaryl‐thiopyryliumsalzen

ChemInform Abstract: PROTON NUCLEAR MAGNETIC RESONANCE STUDY OF THE ADDITION OF METHOXIDE ION TO 2,4,6‐TRIPHENYLPYRYLIUM, 2,4,6‐TRIPHENYLTHIOPYRYLIUM, 1,2,4,6‐TETRAPHENYLPYRIDINIUM AND 1‐(P‐NITROPHENYL)‐2,4,6‐TRIPHENYLPYRIDINIUM CATIONS

Pyryliumverbindungen. XVIII, 2‐Alkoxy‐2H‐pyrane aus tetra‐ und pentasubstituierten Pyryliumsalzen

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