The collision induced loss of carbon monoxide from deprotonated benzyl benzoate in the gas phase. An anionic 1,2-Wittig type rearrangement

Chia, C. S. Brian; Taylor, Mark; Dua, Suresh; Blanksby, Stephen J.; Bowie, John H.

doi:10.1039/a800364e

Cited by 11 publications

(3 citation statements)

References 25 publications

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“…The carbon dioxide loss is competitive with fragmentation via simple homolytic cleavage of the O−O bond and necessitates an efficient rearrangement of the percarboxylate moiety. Such a process has not previously been reported for peroxide anions but, in some respects, is analogous to the expulsion of carbon monoxide from deprotonated benzyl benzoates reported by Bowie and co-workers . These authors proposed two possible mechanisms to account for the observed rearrangement, namely, a nucleophilic aromatic substitution at the ipso carbon (similar to the Smiles rearrangement) , or attack at the ortho position followed by proton transfer.…”

Section: Resultssupporting

confidence: 75%

The Loss of Carbon Dioxide from Activated Perbenzoate Anions in the Gas Phase: Unimolecular Rearrangement via Epoxidation of the Benzene Ring

et al. 2006

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The unimolecular reactivities of a range of perbenzoate anions (X-C6H5CO3-), including the perbenzoate anion itself (X = H), nitroperbenzoates (X = para-, meta-, ortho-NO2), and methoxyperbenzoates (X = para-, meta-OCH3) were investigated in the gas phase by electrospray ionization tandem mass spectrometry. The collision-induced dissociation mass spectra of these compounds reveal product ions consistent with a major loss of carbon dioxide requiring unimolecular rearrangement of the perbenzoate anion prior to fragmentation. Isotopic labeling of the perbenzoate anion supports rearrangement via an initial nucleophilic aromatic substitution at the ortho carbon of the benzene ring, while data from substituted perbenzoates indicate that nucleophilic attack at the ipso carbon can be induced in the presence of electron-withdrawing moieties at the ortho and para positions. Electronic structure calculations carried out at the B3LYP/6-311++G(d,p) level of theory reveal two competing reaction pathways for decarboxylation of perbenzoate anions via initial nucleophilic substitution at the ortho and ipso positions, respectively. Somewhat surprisingly, however, the computational data indicate that the reaction proceeds in both instances via epoxidation of the benzene ring with decarboxylation resulting--at least initially--in the formation of oxepin or benzene oxide anions rather than the energetically favored phenoxide anion. As such, this novel rearrangement of perbenzoate anions provides an intriguing new pathway for epoxidation of the usually inert benzene ring.

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Section: Resultssupporting

confidence: 75%

The Loss of Carbon Dioxide from Activated Perbenzoate Anions in the Gas Phase: Unimolecular Rearrangement via Epoxidation of the Benzene Ring

et al. 2006

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“…Similar rearrangements have been reported by other researchers 8,. 9 Subsequently, the migration of a hydrogen atom from the N‐terminal amino group to the carbonyl group, via a four‐membered ring transition state, led to the elimination of the 45‐Da amide moiety (CH 3 NO). The replacement of both hydrogen atoms on the N‐terminal amino group by methyl groups in compound 6 makes the rearrangement difficult.…”

Section: Resultssupporting

confidence: 82%

Rearrangement with formamide extrusion in the electrospray mass spectra of aminoacylbenzylamines

Chen

Jiang

et al. 2001

Rapid Comm Mass Spectrometry

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Several aminoacylbenzylamines and their analogs were synthesized and analyzed by electrospray ionization mass spectrometry together with high-resolution and tandem mass spectrometric techniques. Fragment ions ([M + H - CH3NO](+)) were observed and attributed to a transfer of the benzyl group to the N-terminal amino group, leading to elimination of formamide. The proposed mechanism is supported by accurate mass measurements, and by experiments on deuterium labeling and variations of functional groups.

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“…(B)] indicated moderate barriers for loss of CO, HCN and SO 2 , and relatively stable phenoxide ( 1c , m / z 184) and arylsulfinate ( 1d , m / z 157) ions as intermediates. As previously considered for the loss of CO from a lactone, CO formation required heterolytic cleavage of two bonds. The intramolecular proton transfer accompanying loss of HCN was supported by deuterium labeling of the arylsulfinate ion 1d (Table ).…”

Section: Resultsmentioning

confidence: 99%

Characterization of multiple fragmentation pathways initiated by collision‐induced dissociation of multifunctional anions formed by deprotonation of 2‐nitrobenzenesulfonylglycine

et al. 2014

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The correlation of anion structure with the fragmentation behavior of deprotonated nitrobenzenesulfonylamino acids was investigated using tandem mass spectrometry, isotopic labeling and computational methods. Four distinct fragmentation pathways resulting from the collision-induced dissociation (CID) of deprotonated 2-nitrobenzenesulfonylglycine (NsGly) were characterized. The unusual loss of the aryl nitro substituent as HONO was the lowest energy process. Subsequent successive losses of CO, HCN and SO2 indicated that an ortho cyclization reaction had accompanied loss of HONO. Other pathways involving rearrangement of the ionized sulfonamide group, dual bond cleavage and intramolecular nucleophilic displacement were proposed to account for the formation of phenoxide, arylsulfinate and arylsulfonamide product ions at higher collision energies. The four distinct fragmentation pathways were consistent with precursor-product relationships established by CID experiments, isotopic labeling results and the formation of analogous product ions from 2,4-dinitrobenzenesulfonylglycine and the Ns derivatives of alanine and 2-aminoisobutyric acid. The computations confirmed a low barrier for ortho cyclization with loss of HONO and feasible energetics for each reaction step in the four pathways. Computations also indicated that three of the fragmentation pathways started from NsGly ionized at the carboxyl group. Overall, the pathways identified for the fragmentation of the NsGly anion differed from processes reported for anions containing a single functional group, demonstrating the importance of functional group interactions in the fragmentation pathways of multifunctional anions.

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The collision induced loss of carbon monoxide from deprotonated benzyl benzoate in the gas phase. An anionic 1,2-Wittig type rearrangement

Cited by 11 publications

References 25 publications

The Loss of Carbon Dioxide from Activated Perbenzoate Anions in the Gas Phase: Unimolecular Rearrangement via Epoxidation of the Benzene Ring

The Loss of Carbon Dioxide from Activated Perbenzoate Anions in the Gas Phase: Unimolecular Rearrangement via Epoxidation of the Benzene Ring

Rearrangement with formamide extrusion in the electrospray mass spectra of aminoacylbenzylamines

Characterization of multiple fragmentation pathways initiated by collision‐induced dissociation of multifunctional anions formed by deprotonation of 2‐nitrobenzenesulfonylglycine

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