On the cyclisation of N-alkylformazans to leucoverdazyls (1,2,3,4-tetrahydro-s-tetrazines)

McConnachie, Gordon; Neugebauer, Franz A.

doi:10.1016/0040-4020(75)85029-0

Cited by 20 publications

(3 citation statements)

References 13 publications

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“…In addition, this reagent combination substantially decreases the quantities of base and alkylating agent required and allows the use of the more available and more stable n-alkyl bromides in place of the iodides. p-Nitrophenyl-substituted triarylverdazyls can be easily obtained by alkylation of the corresponding formazans under the conditions of solid-liquid PTC with the use of the DC18C6/J3a(OH)2.H20 system, whereas the previous method failed due to dominating side reactions (4). On the other hand, the Mannich-type reaction Reaction is promoted by the use of ultrasound, which positively affects the catalyst surface activity and results in higher yields of radicals.…”

Section: Resultsmentioning

confidence: 99%

“…Method (ii) is more general but has the significant disadvantage that a large excess of alkylating agent is required, which leads to alkylation of the intermediate tetrahydro-s-tetrazine (leuco-verdazyl) as a side reaction (2). For triarylformazans containing strongly electron-withdrawing substituents such as nitro groups in the phenyl rings, this side reaction predominates, and verdazyls of this type cannot be obtained by this method (4). The alkylation of formazans is also limited to reactive electrophiles as reaction partners.…”

Section: Introductionmentioning

confidence: 99%

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Syntheses of 3-(substituted)-2,4,6-triphenylverdazyls

Katritzky¹,

Belyakov²,

Durst³

et al. 1994

Can. J. Chem.

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DURST, RUIXLN XU, and NARESH S. DALAL. Can. J. Chem. 72, 1849Chem. 72, (1994.Two series of 2,4,6-triphenylverdazyls substituted at the C(3) position of the heterocyclic ring are obtained using new convenient synthetic methodology. Thus, crown ether assisted solid-liquid phase-transfer catalysis promotes the formation of 3-nalkyl-substituted 2,4,6-triphenylverdazyls in the reactions of 1,3,5-triphenylformazan with n-alkyl bromides. Under PTC conditions, methylation of 3-(4-nitropheny1)-1,5-diphenylformazan with methyl iodide exclusively gives the corresponding verdazyl radical. 3-Substituted 2,4,6-triphenylverdazyls containing various di(cyclo)alkylamino moieties at the C (3) Chem. 72,1849Chem. 72, (1994. Faisant appel B une nouvelle mtthodologie de synthbse, on a obtenu deux series de 2,4,6-triphtnylverdazyles substituCs en position C(3) de l'htttrocycle. La catalyse par transfert de phase solide-liquide assistte par un tther-couronne favorise la formation des 3-n-alkyl-2,4,6-triphtnylverdazyles lors des rtactions des 1,3,5-triphtnylformazane avec des bromures de n-alkyles. Dans des conditions de transfert de phase, la mtthylation du 3-(4-nitrophCny1)-1.5-diphtnylformazane par l'iodure de mtthyle conduit uniquement au radical verdazyle correspondant. On a prtpare des 2,4,6-triphtnylverdazyles substituts par des portions di(cyclo)alkylamino en position (C)3 du cycle verdazyle en faisant rtagir du 1,3,5-triphCnylformazane avec les I-[N,Ndi(cyclo)alkylaminomtthyl]benzotriazoles correspondants en prtsence de monohydrate d'hydroxyde de baryum comme catalyseur efficace. La sonication de cette rtaction permet d'obtenir des rendements beaucoup plus tlevCs de verdazyles. On a synthttist un bis-verdazyle lit aux positions C(3) par deux N. On a caractCrisC tous les radicaux obtenus par des microanalyses, des spectres UV-visible et par spectroscopie RPE.[Traduir par la rtdaction]

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Syntheses of 3-(substituted)-2,4,6-triphenylverdazyls

Katritzky¹,

Belyakov²,

Durst³

et al. 1994

Can. J. Chem.

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show abstract

“…for the synthesis of tetrazine derivatives, and the most frequently used method for the preparation of 1,2,3,4-tetrahydro-1,2,4,5-tetrazines is the cyclization of alkylformazanes by heating or base treatment [7].…”

Section: Introductionmentioning

confidence: 99%