The nature and fragmentation pathways of the molecular ions of some arylureas, arylthioureas, acetanilides, thioacetanilides and related compounds

Baldwin, Michael A.; Loudon, A. G.; Maccoll, Allan; Webb, Kenneth S.

doi:10.1002/oms.1210111109

Cited by 24 publications

(7 citation statements)

References 32 publications

(2 reference statements)

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“…The mechanism for the loss of the halogen presumably follows a path similar to that proposed for ortho-halogenated phenylureas, thioureas, carbamates [10,11], formamidines [12,13], and phenylhydrazones and 2,4-dinitrophenylhydrazones of benzaldehydes and acetophenones [14]. Investigations by Grützmacher and coworkers have established that the fragmentation follows a two-step addition/dissociation mechanism via a -complex (10) leading to a benzoxazolium ion (11, Scheme 1) [11,13].…”

Section: Resultsmentioning

confidence: 90%

Ortho effect in electron ionization mass spectrometry of N-acylanilines bearing a proximal halo substituent

Jariwala

Figus

Attygalle

2008

J. Am. Soc. Mass Spectrom.

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Electron ionization (EI) mass spectra are not very helpful for characterizing ortho, meta, and para isomers of underivatized haloanilines since their spectra are virtually identical. In contrast, when the amino group of chloro-, bromo-, or iodoanilines is transformed to an N-formyl, N-acetyl, or N-benzoyl derivative, the spectra of the derivatives reveal a highly dramatic loss of a halogen radical, instead of an HX elimination usually expected from an "ortho effect." For example, the spectra of N-formyl, N-acetyl, and N-benzoyl derivatives of ortho isomers of chloro-, bromo-, and iodoanilines show a very prominent peak at m/z 120, 134, and 196, respectively, for the loss of the corresponding halogen atom.

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Section: Resultsmentioning

confidence: 90%

Ortho effect in electron ionization mass spectrometry of N-acylanilines bearing a proximal halo substituent

Jariwala

Figus

Attygalle

2008

J. Am. Soc. Mass Spectrom.

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“…Ortho-interaction should be responsible for the loss of a methyl cyclopropyl radical. 12,13 Benzothiazole forms in this process (Scheme 8). Nevertheless, the processes involving interaction of the thioamide group with the methylcyclopropyl moiety take place.…”

Section: Resultsmentioning

confidence: 99%

Cyclization of 2-Acyl- and 2-Thioacylamino-Benzylcyclopropanes in the Gas Phase and Solution

Lebedev

Giorgi

Maloshitskaya

et al. 2009

Eur J Mass Spectrom (Chichester)

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Mass spectrometry proved itself to be a powerful tool to predict the directions and yields of mono- molecular reactions of organic compounds. Electron ionization (EI) and electrospray ionization (ESI) were used to study possible transformations of N-(ortho-cyclopropylmethylphenyl)arylamides I and N-(ortho- cyclopropylmethylphenyl)arylthioamides II as well as their para-isomers III and IV in a mass spectrometer and to predict directions and yields of their acid catalyzed cyclization reactions. Several five-eight-membered heterocycles were proposed as possible products of intramolecular transformations of compounds I and II. Reactions of compounds I and II in sulfuric acid solutions were carried out and the results obtained were compared with mass spectrometric data. Surprisingly, EI of the studied compounds mimics their solution reactions better than ESI.

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“…2. Interaction of the substituted N-(ortho-cyclopropylphenyl)-N=-aryl ureas (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)) and N-(ortho-cyclopropylphenyl)-N=-aryl thioureas (15)(16)(17)(18)(19)(20)(21)(22)(23)) with strong acids is a convenient method for synthesis of substituted benzoxazines and benzothiazines.…”

Section: Discussionmentioning

confidence: 99%

“…Substituted N-(ortho-cyclopropylphenyl)-N=-aryl ureas (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14) and N-(ortho-cyclopropylphenyl)-N=-aryl thioureas (15)(16)(17)(18)(19)(20)(21)(22)(23) possess four nucleophilic sites [N, N=, O (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14) or S (15)(16)(17)(18)(19)(20)(21)(22)(23), and the ortho-position of the aromatic ring attached to N=], which are able to attack the charged cyclopropyl moiety. Therefore, at least four heterocycles (P 1 -P 4 ) can be formed in the intramolecular cyclization reaction.…”

mentioning

confidence: 99%

Cyclization of the substituted N-(Ortho-cyclopropylphenyl)-N′-aryl ureas and thioureas in the gas phase and solution

Lobodin

Федотов

Dem’yanov

et al. 2005

J. Am. Soc. Mass Spectrom.

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Electron ionization (EI), chemical ionization (CI), tandem mass spectrometry, high-resolution measurements, and labeling studies as well as quantum chemical calculations were used to understand the behavior of the molecular radical cations (EI) and protonated molecules (CI) of substituted N-(ortho-cyclopropylphenyl)- N=-aryl ureas and N-(ortho-cyclopropylphenyl)-N=-aryl thioureas in a mass spectrometer. Fragmentation schemes and possible mechanisms of primary isomerization were proposed. According to the fragmentation pattern, formation of the corresponding benzoxazines and benzothiazines was considered as the major process of isomerization of the original M ϩ· and MH ϩ , although some portions of these ions definitely transformed into other structures. M ass spectrometry has been proven to be a powerful, rapid method for the prediction of the direction and yields of monomolecular reactions of organic compounds in solution [1]. Previously, we successfully used mass spectrometry to study cyclization of various diazo compounds [2] and orthosubstituted phenylcyclopropanes [3]. The spectral conclusions for a representative series of N-(ortho-cyclopropylphenyl)benzamides were used to confirm the presence of the predicted heterocycles in solution. The cyclization products of the molecular ions for these benzamides were identical to those synthesized in the condensed phase [4,5]. In the present study, we continue research in this area, investigating the possibility of rearrangements of substituted N-(ortho-cyclopropylphenyl)-N=-aryl ureas (1-14).) and N-(ortho-cyclopropylphenyl)- N=-aryl thioureas (15-23), structurally related to the earlier studied acetamides [6] and benzamides [4,5]. These compounds were expected to undergo EI induced and acid catalyzed cyclization in a similar manner.Substituted N-(ortho-cyclopropylphenyl)- N=-aryl ureas (1-14) and N-(ortho-cyclopropylphenyl)-N=-aryl thioureas (15-23) possess four nucleophilic sites [N, N=, O (1-14) or S (15-23), and the ortho-position of the aromatic ring attached to N=], which are able to attack the charged cyclopropyl moiety. Therefore, at least four heterocycles (P 1 -P 4 ) can be formed in the intramolecular cyclization reaction.

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The nature and fragmentation pathways of the molecular ions of some arylureas, arylthioureas, acetanilides, thioacetanilides and related compounds

Cited by 24 publications

References 32 publications

Ortho effect in electron ionization mass spectrometry of N-acylanilines bearing a proximal halo substituent

Ortho effect in electron ionization mass spectrometry of N-acylanilines bearing a proximal halo substituent

Cyclization of 2-Acyl- and 2-Thioacylamino-Benzylcyclopropanes in the Gas Phase and Solution

Cyclization of the substituted N-(Ortho-cyclopropylphenyl)-N′-aryl ureas and thioureas in the gas phase and solution

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