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  • 1
    Electronic Resource
    Electronic Resource
    Photochemische Stickstoff-Eliminierung aus 1-(1-Alkenyl)-4-tert-butyl-1,4-dihydro-5H-tetrazol-5-onen. Konkurrenz zwischen Methanol-Addition und Cyclisierung einer dipolaren Zwischenstufe (1984)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 2761-2778 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Photochemical Elimination of Nitrogen from 1-(1-Alkenyl)-4-tert-butyl-1,4-dihydro-5H-tetrazol-5-ones. Competition between Addition of Methanol and Cyclization of a Dipolar IntermediateThe 4-tert-butyl-1-vinylterazolones 12a - c and the tetrazolones 13 and 14 are synthesized from the 5-chlorotetrazole 7 and the tetrazolone 9 via several routes. Bis(benzonitrile)palladium dichloride catalyses the O → N-Claisen rearrangement 8 → 11, the allyl → vinyl rearrangements 11a → 12b and 11b → 12c, as well as the equilibration 13 → 14. On 254 nm photolysis of the vinyltetrazolones 12 nitrogen is extruded and cyclic and/or acylic products of primary photo-intermediates are formed: In [D3]acetonitrile as solvent, 77% of 1-tert-butylimidazolone 16 arises from 12a, while the tetrazolones 12b, c produce only complex mixtures. In methanol as solvent, the methanol adduct 20a (23%) of the intermediate imidazolone 15a and the acyclic N-(1,2-dimethoxyethyl)urea 22a (32%) are obtained besides 45% of 16. In contrast, from 12c in methanol the corresponding urea 22c is formed almost quantitatively as the only product. In [D4]methanol solution of (E,Z)-12b a ratio of 4-methoxyimidazolidinone 20 b to the diastereomeric ureas 22 b of 22: 78 is observed. With decreasing amounts of [D4]methanol in [D4]methanol/[D3]acetonitrile mixtures, the imidazolidinone 20 b increases at the expense of the ureas 22 b. A 20 b: 22 b ratio of 98: 2 is reached in [D3]acetonitrile containing 3-6% [D4]methanol. This indicates a competition between the cyclization (affording 20 b via 15 b) and the methanol addition (producing 22 b via 21 b) of a dipolar photo-intermediate. The structure of the photo-products are confirmed by independent synthesis of 16 and by their high field proton and carbon-13 NMR spectra.
    Notes: Aus dem 5-Chlortetrazol 7 und dem Tetrazolon 9 werden auf verschiedenen Wegen die 4-tert-Butyl-1-vinyltetrazolone 12a - c sowie die Tetrazolone 13 und 14 hergestellt. Bei der 254-nm-Photolyse der 1-Vinyltetrazolone 12 erhält man in Abhängigkeit von Struktur und Reaktionsbedingungen das Imidazolon 16, die 4-Methoxyimidazolidinone 20 und/oder die N-(1,2-Dimethoxyalkyl)harnstoffe 22. Die Ergebnisse sprechen für eine Konkurrenz zwischen Cyclisierung (→ 15b → 20b) und Methanol-Addition (→ 21b → 22b) einer dipolaren Photozwischenstufe. Die Struktur der Photoprodukte wird durch unabhängige Synthese von 16 sowie Hochfeld-1H-und 13C-NMR-Spektren bewiesen.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19841170818
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  • 2
    Electronic Resource
    Electronic Resource
    Photochemische Stickstoff-Eliminierung aus 1,4-Dihydro-1-phenyl-5H-tetrazol-5-onen und -thionen. Benzimidazolone und Carbodiimide (1985)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 526-540 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Photoextrusion of Nitrogen from 1,4-Dihydro-1-phenyl-5H-tetrazol-5-ones and -thiones. Benzimidazolones and CarbodiimidesAlkylation of 1-phenyltetrazolone 10a with 2-cyclohexen-1-yl bromide followed by dehydrogenation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone permits introduction of a phenyl group at N-4 of the tetrazole ring via the sequence 10a → 10f → 10g. The photoextrusion of molecular nitrogen from the (N-4)-substituted 1-phenyltetrazolones, 10a (hydrogen), 10b (methyl), 10d,e (propenyl), and 10g (phenyl) produces essentially quantitative yields of the corresponding benzimidazolones 14a,b,d,e,g. On irradiation of the 1-phenyltetrazolethiones 8 b, f, g the carbodiimides 22b, f, g are obtained together with molecular nitrogen and sulfur, while 8a affords phenylcyanamide (25). In contrast to the thermolysis, which is known to give 2-(methylamino)benzothiazole (21 b), photolysis of the (phenylimino)-1,2,3,4-thiatriazole 24, an isomer of methylphenyltetrazolethione 8b, also yields molecular nitrogen, sulfur, and methylphenylcarbodiimide (22b).
    Notes: Die nachträgliche Einführung einer Phenylgruppe an N-4 des Tetrazolrings gelingt erstmals, nämlich durch Alkylierung des 1-Phenyltetrazolons 10a mit 2-Cyclohexen-1-ylbromid zu 10f und anschließende Dehydrierung mit 2,3-Dichlor-5,6-dicyan-1,4-benzochinon zu 10 g. Die photochemische Stickstoff-Eliminierung aus 1-Phenyltetrazolonen, unsubstituiert (10a) oder mit einer Methyl- (10 b), Propenyl- (10d,e) oder Phenylgruppe (10 g) an N-4, ergibt nahezu quantitativ die entsprechenden Benzimidazolone 14a,b,d,e,g. Durch Bestrahlung der 1-Phenyltetrazolthione 8b, f, g erhält man neben Stickstoff und Schwefel die Carbodiimide 22b, f, g, während aus 8a Phenylcyanamid (25) entsteht. Im Gegensatz zur bekannten Thermolyse, die zu 2-(Methylamino)-benzothiazol (21b) führt, ergibt die Photolyse des (Phenylimino)-1,2,3,4-thiatriazols 24, ein Isomeres des Methylphenyltetrazolthions 8b, ebenfalls Stickstoff, Schwefel und Methylphenyl-carbodiimid (22b).
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19851180213
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  • 3
    Electronic Resource
    Electronic Resource
    Photochemische Stickstoff-Eliminierung aus 1-Alkenyl-4-alkyl-1,4-dihydro-5H-tetrazol-5-onen und -thionen. Diaziridinone und Carbodiimide mit Alkenylsubstituenten (1983)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 116 (1983), S. 3427-3437 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Photoextrusion of Nitrogen from 1-Alkenyl-4-alkyl-1,4-dihydro-5H-tetrazol-5-ones and -thiones. Diaziridinones and Carbodiimides with Alkeyl SubstituentsTo test the possibility that tetrazolones and tetrazolthiones photoextrude nitrogen producing intermediates which can be trapped via intramolecular [3 + 2]-cycloaddition to C=C double bonds, several tetrazolones 8 and -thiones 13 with alkenyl substituents were synthesized and subjected to photolysis. On 254 nm photolysis of the tetrazolones 8 in [D3]acetonitrile, [D12]cyclohexane, and [D14]methylcyclohexane as solvents, nitrogen was extruded and diaziridinones 17 were formed in 80-90% yield besides small amounts of by-products (〈 10%). When the photolysis was carried out in [D3]acetonitrile, the latter were identified as urea 18 (photoreduction product) and as the hydrolysis product of 17. The thiones 13 photoextruded nitrogen and sulfur producing carbodiimides. Trapping of an intermediate via [3 + 2]-cycloaddition was not observed.
    Notes: Um zu prüfen, ob aus Tetrazolonen und Tetrazolthionen durch photochemische Stickstoff-Eliminierung Zwischenstufen entstehen, die sich durch intramolekulare [3 + 2]-Cycloaddition an C=C-Doppelbindungen abfangen lassen, wurden einige Tetrazolone 8 und -thione 13 mit Alkenylsubstituenten dargestellt und photolysiert. Mit Licht von λ = 254 nm erhielt man aus den Tetrazolonen 8 in [D3]Acetonitrile, [D12]Cyclohexan und [D14]Methylcyclohexan Stickstoff und 80-90% Diaziridinone 17 neben geringen Mengen Nebenprodukten (〈 10%), die sich in [D3]Acetonitril als Photoreduktionsprodukt, Harnstoff 18, und als Hydrolyseprodukt von 17 erwiesen. Die Thione 13 eliminierten beim Belichten Stickstoff und Schwefel und gaben Carbodiimide. In keinem Fall beobachtete man intramolekulare [3 + 2]-Cycloaddition einer Zwischenstufe.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19831161017
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  • 4
    Electronic Resource
    Electronic Resource
    Photochemische Stickstoff-Eliminierung aus phenylsubstituierten 1,4-Dihydro-5-imino-5H-tetrazolen. Folgeprodukte phenylsubstituierter Tris(imino)methan-Diradikale (1985)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 118 (1985), S. 2164-2185 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Photochemical Elimination of Molecular Nitrogen from Phenyl-Substituted 1,4-Dihydro-5-imino-5H-tetrazoles. Products of Phenyl-Substituted Tris(imino)methane DiradicalsThe reaction of 5-(methylthio)tetrazolium salts 11 with primary amines produces the phenyl-substituted 5-iminotetrazoles 7b - h. In contrast to the results of the electron impact-induced fragmentation in the mass spectrometer, irradiation of the 5-iminotetrazoles 7b - g does not effect the possible isomerizations 7b ⇌ 7c, 7f → 7i, 7d ⇌ 7e and 7g → 7j, but only loss of molecular nitrogen. Thus, 2-aminobenzimidazoles 8 are formed as major photo products, besides small amounts of the guanidines 12 and 10% 2-aminodibenzo-1,3-diazepine 16a in the case of the 5-iminotetrazoles 7d, e bearing two phenyl substituents. From each isomer of the pairs 7b, c and 7d, e the same ratio of the photo products 8a, 12a and 8b, c, 12b, 16a, respectively, is obtained. Irradiation of the deuterium labelled 5-iminotetrazoles 7f and g leads to complete scrambling of the deuterium over the possible positions in the photo products. The results demonstrate that the ring nitrogen atoms N-1 and N-4 and the exocyclic nitrogen atom become equivalent with respect to product formation. Phenyl-substituted tris(imino)methane diradicals 22, produced via photo extrusion of molecular nitrogen from the 5-iminotetrazoles 7b - g, are postulated as fully equilibrated intermediates.
    Notes: Aus den 5-(Methylthio)tetrazoliumsalzen 11 und primären Aminen werden die phenylsubstituierten 5-Iminotetrazole 7b - h hergestellt. Im Gegensatz zur Elektronenstoß-induzierten Fragmentierung im Massenspektrometer beobachtet man beim Belichten der 5-Iminotetrazole 7b - g keine der denkbaren Isomerisierungen 7b ⇌ 7c, 7f → 7i, 7d ⇌ 7e und 7g → 7j sondern nur Verlust von Stickstoff. Dabei entstehen hauptsächlich 2-Aminobenzimidazole 8 neben geringen Mengen Guanidin 12 und - im Falle der 5-Iminotertrazole 7d, e mit zwei Phenylgruppen - ca. 10% 1-Aminodibenzo-1,3-diazepin 16a. Aus jedem Isomeren der Paare 7b, c bzw. 7d, e erhält man das gleiche Verhältnis der Photoprodukte 8a, 12a bzw. 8b, c, 12b, 16a. Beim Belichten der Deuterium-markierten 5-Iminotetrazole 7f und g verteilt sich das Deuterium gleichmäßig auf die möglichen Positionen in den Photoprodukten. Diese Ergebnisse zeigen, daß die Ringstickstoffatome N-1, N-4 und das exocyclische Stickstoffatom bezüglich der Produktbildung äquivalent werden. Das spricht dafür, daß Photoextrusion von Stickstoff aus den 5-Iminotetrazolen 7b - g phenylsubstituierte Tris(imino)methan-Diradikale 22 entstehen.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19851180603
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  • 5
    Electronic Resource
    Electronic Resource
    Photochemical Formation of Heteromethylenecyclopropanes, 27Part 26: Ref.[1].. Annulated Tetrazolium Salts (1997)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1997 (1997), S. 671-683 
    Details
    ISSN: 0947-3440
    Keywords: Alkylations ; Annulation ; Azides ; Cations ; Cyclizations ; Cycloadditions ; Heterocycles ; Lithiation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Lithiation of the annulated tetrazoles 6a, c with butyllithium yields the N-lithiotetrazoles 7a, c which are allowed to react with alkyl halides. Alkylation at the α-carbon atom is observed in the reaction with methyl iodide (→ 6b, d), 1-bromo-2-chloroethane (7c→14a), and 1,3-dibromopropane (→ 16, 17), while 1,2-dichloro- and 1,2-dibromoethane give other products, viz. 11-13. Quaternisation of 6 with dimethyl sulphate affords mixtures of 1-methyl- (1) and 2-methyltetrazolium salts (8) (3:1-4:1) from which the hexafluorophosphates 1 PF6 are obtained by crystallisation. Methyl triflate converts the ω-azidonitriles 9 into the N-methylnitrilium triflates 10 which immediately undergo an intramolecular 1,3-dipolar cycloaddition to afford the 1-methyltetrazolium triflates 1 F3CSO3. Cyclisation of 16 by intramolecular N-alkylation furnishes the bisannulated tetrazolium bromide 3a · Br. Attempts to obtain the lower homologue 15, either from 14a or from 17, met with failure. Instead, 17 rearranges via 15b into 14b. The α-branched tetrazole 24 is synthesised from ethyl cyanoacetate and the bromide 18. Double cyclisation of 24 affords the bisannulated tetrazolium chloride 3b · Cl. The analogous scheme, envisaged for the synthesis of the lower homologue 32, failed in the last step owing to the high strain of this system.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.199719970408
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