787. The scope and mechanism of carbohydrate osotriazole formation. Part IV. Debromination and oxidation of substituted osazones and osotriazoles

Khadem, H. El; El-Shafei, Z. M.; Mohammed, Y. S.

doi:10.1039/jr9600003993

Cited by 14 publications

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“…This value is consistent with that reported in the literature. 36 2-(3-Chlorophenyl)-2H-[1,2,3]triazole (1e) was prepared from 3-chloro-phenylhydrazine hydrochloride using a described procedure. 19 Yield: 88%.…”

Section: Methodsmentioning

confidence: 99%

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Deproto-metallation and computed CH acidity of 2-aryl-1,2,3-triazoles

et al. 2012

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2-Aryl-1,2,3-triazoles were synthesized by cyclization of the corresponding glyoxal arylosazones, generated from commercial arylhydrazines. The deproto-metallation of 2-phenyl-1,2,3-triazole was attempted using different 2,2,6,6-tetramethylpiperidino-based mixed lithium-metal (Zn, Cd, Cu, Co, Fe) combinations, giving results in the case of Zn, Cd, and Cu. The lithium-zinc combination was next selected to apply the deprotonation-iodination sequence to all the 2-aryl-1,2,3-triazoles synthesized. The results were analyzed with the help of the CH acidities of the substrates, determined in THF solution using the DFT B3LYP method.

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Section: Methodsmentioning

confidence: 99%

“…This value is 10 consistent with that reported in the literature. 36 Typical procedure for the deproto-metallation followed by trapping with electrophiles. To a stirred, cooled (0 °C) solution of 2,2,6,6-tetramethylpiperidine (0.25 mL, 1.5 mmol) in THF (5 45 mL) was added BuLi (about 1.6 M hexanes solution, 1.5 mmol).…”

Section: -Phenyl-2h-[123]triazole (1a)mentioning

confidence: 99%

Deproto-metallation and computed CH acidity of 2-aryl-1,2,3-triazoles

et al. 2012

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“…113-114°, prepared previously (8) by treatment of glyoxal bisphenylhydrazone with bromine in aqueous suspension. This reaction presumably involves initial para brosnination of the bisphenylhydrazone, followed by oxidative cyclization, since bromine in aqueous suspension has no effect on I ; although the structure of the product obtained previously (8) was not proved by an unambiguous synthesis, it could be subject to little doubt in view of the demonstrated generality of the initial para broinination of the bisarylhydrazones of glucose and glyoxal before their oxidative cyclization to triazoles (cf. ref.…”

Section: Notesmentioning

confidence: 99%

Reactions of Phenyl-Substituted Heterocyclic Compounds: Iv. Bromination of 2-Phenyl-1,2,3,2h-Triazole

Lynch¹

1963

Can. J. Chem.

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IV. BROMINATION OF 2-PHENYL-1,2,3,2H-TRIAZOLEAddition of silver sulphate t o a solution of bromine in concentrated sulphuric acid produces a highly reactive electrophilic brominating species, which is probably AgBr,+ (cf. Arotsky and Symons (1)). In previous work (2), we have used this combination of reagents to effect selective para bromination of 1-phenylpyrazole (which probably reacts in the form of its conjugate acid under the reaction conditions).The present note reports the application of this bromination technique t o 2-phenyl-1,2,3,2H-triazole (I), where 2-9-bromophenyl-1,2,3,2H-triazole (11), m.p. 113O, is obtained. Apparently, the highly reactive "positive bromine" overcomes the deactivating influence of the electron-attracting triazole ring (cf. ref.3), even under circumstances where this influence may be enhanced as a result of protonation in the strongly acidic reaction medium.The proton magnetic resonance spectrum of the bromination product of I offered a particularly simple proof of structure 11: it showed a typical pattern centered a t a T value of 2.25 for the four protons of the P-bromophenyl group, and a single line a t r 2.25 for the two equivalent protons of the triazole ring. Analysis of the AzBz pattern assuming that JAB' = 0 and JA = J B (cf. Richards and Schaefer (4)) gave J A B = 9.4 C/S, and an A-B chemical shift separation of 0.39 T. Since the triazolyl group in derivatives of I is known to be strongly electron attracting (3), it is presumed that the protons ortho to the triazole ring would have the lower r values in the absence of spin-spin coupling, and on this basis it is possible to deduce r 2.056 for the protons ortho t o the triazole ring, and T 2.445 for the protons ortho to the bromine atom. If we assume, following Pople, Schneider, and Bernstein (5), that the chemical shift of a proton in a 1-X, 4-Y benzene will be X,+Ym a t the 2-position, and X,+Y, a t the 3-position (X,, X, and Y,, Ym are the chemical shifts of the ortho and meta protons in the monosubstituted benzenes C6HbX and CGHSY), and also that the chemical shifts of the protons influenced by the triazolyl group are similar to those under the corresponding influence of a nitro group (supporting evidence for this assumption is presented below), these T values appear reasonable.The T value 2.25, observed for the protons of the triazole ring in 11, is consistent with the positions noted for the proton resonances in other five-membered nitrogen heterocyclic compounds. Thus, Reddy, Hobgood, and Goldstein (6) found T 2.30 and 2.86 for the 2-and 4(5)-protons of imidazole, while Moore and Whittaker (7) found r 1.77 for the ring proton of 2-ethyltetrazole.

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Alkyl‐ or Aryl‐Monosubstituted 1,2,3‐Triazoles

1980

Chemistry of Heterocyclic Compounds: A Series of Monographs

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787. The scope and mechanism of carbohydrate osotriazole formation. Part IV. Debromination and oxidation of substituted osazones and osotriazoles

Cited by 14 publications

References 0 publications

Deproto-metallation and computed CH acidity of 2-aryl-1,2,3-triazoles

Deproto-metallation and computed CH acidity of 2-aryl-1,2,3-triazoles

Reactions of Phenyl-Substituted Heterocyclic Compounds: Iv. Bromination of 2-Phenyl-1,2,3,2h-Triazole

Alkyl‐ or Aryl‐Monosubstituted 1,2,3‐Triazoles

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