Synthesis and mass spectra of some 2-methyl and 2-phenyl-5-(polyacetoxyalkyl)-1,3,4-oxadiazoles and their conformations in solution

The tandem mass (MS/MS) spectra of ammonium ion, metal ion and ligated metal ion adducts of chain-extended acyclic nitro-containing deoxyglucose and deoxygalactose derivatives have been studied. The ammonium adducts fragment primarily by elimination of ammonia followed by acetic acid, thus not giving much structural information. In contrast, cationization of these compounds by metal ions and ligated metal ions gave structurally informative and useful fragment ions on MS/MS. The metal ions and ligated metal ions play an important role in controlling and directing fragmentation. Retro-aldol fragmentation is facilitated by metal ions such as Li(+), Na(+), Ag(+) and Cu(+), whereas the adducts with higher alkali metal ions such as Rb(+) and Cs(+) fragment to give only the corresponding metal ions. The divalent metal ions such as Cu(2+) and Ba(2+) also induce retro-aldol fragmentation. However, the charge is carried by the aldehyde fragment in the case of Cu(2+) adducts, whereas the nitroalkane fragment carries the charge in the case of Ba(2+) adducts. Ligated metal ions such as ZnCl(+), CuCl(+), InCl(2) (+) and BaCl(+) also behave similarly and induce retro-aldol fragmentation in these acyclic sugars. Both the metal ion and ligated metal ion adducts can fragment by elimination of metal-containing neutral molecules.

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“…The mass spectra of acyclic monosaccharide derivatives with different structures have been reported 19–27. Recently, Kovacik et al 28.…”

mentioning

confidence: 99%

Tandem mass spectra of ammonium ion, metal ion and ligated metal ion adducts of acyclic sugar derivatives

Madhusudanan

Kumar

Pathak

et al. 2003

Rapid Comm Mass Spectrometry

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“…Esses resultados parecem indicar que o tetrazol 9 é pouco reativo para fosforilação com cloreto de dietilfosforila, ao menos nas condições utilizadas. A confirmação da fosforilação regiosseletiva em C-5 de 9 foi feita com base na análise do espectro de RMN 13 C, DEPT-135 de 3. Os sinais em δ 70,9 e δ 70,8 ppm, atribuídos a C-5 e C-4, respectivamente, são dupletos (J C-5-P = 5,9 Hz, J C-4-P = 7,3 Hz), resultantes do acoplamento desses carbonos com o átomo de fósforo do grupo dietilfosforila em C-5.…”

Section: Resultsunclassified

“…13 Tentativa de remoção dos grupos protetores de 10 (MeONa/MeOH) forneceu, após elaboração, um sólido cujo espectro no infravermelho apresentou , indicando a abertura do anel 1,3,4-oxadiazólico. A presença de um singleto em δ 1,87 ppm com integral para três átomos de hidrogênio no espectro de RMN 1 H, bem como a presença de um carbono em δ 20,5 ppm no espectro de RMN 13 C do produto, característico de grupo metila ligado a carbonila, permitiram atribuir a esse a estrutura da hidrazida 12, obtida com 28% de rendimento.…”

unclassified

Síntese e modificações de derivados heterocíclicos de D-arabinose: potenciais inibidores de glicose-6-fosfato isomerase e de glicosamina-6-fosfato sintase

Viana¹,

Prado²,

Alves³

2008

Quím. Nova

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Recebido em 21/11/07; aceito em 4/4/08; publicado na web em 11/9/08 SYNTHESIS AND MODIFICATIONS OF HETEROCYCLIC DERIVATIVES OF D-ARABINOSE: POTENTIAL INHIBITORS OF GLUCOSE-6-PHOSPHATE ISOMERASE AND GLUCOSAMINE-6-PHOSPHATE SYNTHASE. The synthesis of -5-(D-arabino-1,2,3,4-tetrahydroxybutyl)tetrazole and -2-(d-arabino-1,2,3,4-tetra-acetoxybutyl)-5-methyl-1,3,4-oxadiazole from d-arabinose is described. Attempts at removing the protecting groups of the oxadiazole derivative were unsuccessful, leading to products resulting from the opening of the oxadiazole ring. The unprotected tetrazole derivative was selectively phosphorylated at the primary hydroxyl group with diethylphosphoryl chloride. The resulting 5-[d-arabino-4-(diethylphosphoryloxy)-1,2,3-trihydroxybutyl]tetrazole is a protected form of a potential inhibitor of the enzymes glucose-6-phosphate isomerase and glucosamine synthase.

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“…The tetrazoles are a family of heterocycles with a great variety of applications in the area of medicine,1 and their synthesis presents an interesting approach to obtaining other bioactive derivatives 2, 3. We have described the conversion of 5‐polyacetoxyalkyl‐ and other protected carbohydrate tetrazole derivatives into the corresponding 2,5‐disubstituted‐1,3,4‐oxadiazole derivatives,4, 5 working in the condensed phase by a rearrangement reaction using an acylating reactive. The 5‐substituted tetrazole structure can be considered as a hybrid between two tautomeric forms (Scheme ), of which only structure II can rearrange to lose a nitrogen molecule and afford the oxadiazole structure.…”

Section: Introductionmentioning

confidence: 99%

Gas‐phase conversion of tetrazoles to oxadiazoles: isolation and characterization of the N‐acylated intermediate

Seldes¹,

D’Accorso²,

Souto³

et al. 2001

J. Mass Spectrom.

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The 5-substituted tetrazole ring was reacted in the gas phase with an acyl ion generated as the secondary reactive chemical ionization plasma in the mass spectrometer. The product ions obtained, among others, were proposed as the rearranged 2,5-disubstituted-1,3,4-oxadiazole nucleus. Its structure was demonstrated by comparison of the product ion spectrum of the 2,5-disubstituted-1,3,4-oxadiazole derivative obtained by condensed-phase reaction and the product ion spectrum of the oxadiazole derivative generated in situ by reaction of the 5-substituted tetrazole derivative with the acyl plasma. It was proposed that the mechanism of this transformation involved the presence of an acylated tetrazole intermediary, which could not be isolated in the condensed phase, followed by the rearrangement, with nitrogen loss, to afford the oxadiazole derivative. Under our conditions we were able to isolate the intermediate ion in the first field free region and demonstrate its structure by collision induced dissociation-tandem mass spectrometry.

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Synthesis and mass spectra of some 2-methyl and 2-phenyl-5-(polyacetoxyalkyl)-1,3,4-oxadiazoles and their conformations in solution

Cited by 16 publications

References 10 publications

Tandem mass spectra of ammonium ion, metal ion and ligated metal ion adducts of acyclic sugar derivatives

Tandem mass spectra of ammonium ion, metal ion and ligated metal ion adducts of acyclic sugar derivatives

Síntese e modificações de derivados heterocíclicos de D-arabinose: potenciais inibidores de glicose-6-fosfato isomerase e de glicosamina-6-fosfato sintase

Gas‐phase conversion of tetrazoles to oxadiazoles: isolation and characterization of the N‐acylated intermediate

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