Mass spectrometric and thermal fragmentation of 1-substituted-3-phenyl-2-thioureas

Shapiro, Robert H.; Serum, James W.; Duffield, A. M.

doi:10.1021/jo01265a048

Cited by 42 publications

(8 citation statements)

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“…Although the mechanism leading to b (Scheme 1) could be established by deuterium labelling, this is no clear evidence for a mass spectrometric fragmentation, since a 4-membered cyclic transition state can also be operative in the thermolysis of thioureas. 16 It is interesting to note that typical thiourea fragment ions could not be detected in 1-5.…”

Section: Resultsmentioning

confidence: 99%

Mass spectroscopy of natural products. XI—Mass spectroscopic investigations of N-6 substituted ergoline derivatives

Schmidt

Seifert

Härtling

et al. 1981

Biol. Mass Spectrom.

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Section: Resultsmentioning

confidence: 99%

Mass spectroscopy of natural products. XI—Mass spectroscopic investigations of N-6 substituted ergoline derivatives

Schmidt

Seifert

Härtling

et al. 1981

Biol. Mass Spectrom.

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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.…”

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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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“…Shapiro et a1. 32 32 for the 1-substituted-3-phenyl thioureas may well be wrong and the hydrogen needed for the back transfer would have to come from one of the nitrogens. It seems more likely that it comes from the anilino nitrogen since in the case of N-phenyl, N-methylthiourea this ion is of very much smaller abundance, although P,[M -HI+, 9.70 eV is very similar to that for phenylthiourea.…”

Section: Table 5 Variations In the [Clchn]t/[m -Cl]+ Ratios With Ementioning

confidence: 99%

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

Baldwin¹,

Loudon²,

Maccoll³

et al. 1976

Org. Mass Spectrom.

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Mass spectrometric and thermal fragmentation of 1-substituted-3-phenyl-2-thioureas

Cited by 42 publications

References 0 publications

Mass spectroscopy of natural products. XI—Mass spectroscopic investigations of N-6 substituted ergoline derivatives

Mass spectroscopy of natural products. XI—Mass spectroscopic investigations of N-6 substituted ergoline derivatives

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

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

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