On the structure of [C9H6O]+· ions originating by electron impact induced decomposition of chalcone

Ardanaz, C. E.; Kavka, J.; Curcuruto, Ornella; Traldi, Pietro; Guidugli, Federico; Somogyi, Árpád

doi:10.1002/rcm.1290051115

Cited by 11 publications

(10 citation statements)

References 8 publications

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“…Eighteen pure compounds were used as reference standards, among them 6-arabinopyranosyl-8-glucopyranosyl-5,7dihydroxyflavone (1), liquiritin (4), 3,4,3 0 ,4 0 -tetrahydroxy-2methoxychalcone (7), visidulin III (13), licochalcone B (18), liquiritigenin (19), calycosin (20), quercetin (21), baicalin (27), echinatin (29), norwogonine (35), isorhamnetin (36), baicalein (38), isoliquiritigenin (41), formononetin (43), chrysin (45) and oroxylin A (48) were isolated from the LXD in our laboratory, and naringin (6) was provided by the Shanghai R&D Centre for Standardization of Traditional Chinese Medicines (Shanghai, China) ( Fig. 1).…”

Section: Experimental Materialsmentioning

confidence: 99%

“…This is reasonable because cyclization of 2 0 -hydroxychalcones to flavanones has been reported in a number of studies demonstrating an intramolecular equilibrium being present between a flavanone-type and a chalcone-type molecular ion. [38][39][40][41] 3,3 0 ,4,4 0 -Tetrahydroxy-6-methoxychalcone (7), licochalcone B (18) and echinatin (29) were identified by comparison with the corresponding reference standards. In the MS 2 experiment, 7, 18 and 29 underwent characteristic X B À fragmentation to produce the ions at m/z 191, 191 and 175, respectively.…”

Section: Chalconesmentioning

confidence: 99%

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Characterization of fifty‐one flavonoids in a Chinese herbal prescription Longdan Xiegan Decoction by high‐performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry and photodiode array detection

Wang

Yang

et al. 2008

Rapid Comm Mass Spectrometry

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High-performance liquid chromatography coupled to electrospray ionization (ESI) tandem mass spectrometry and photodiode array detection (HPLC-DAD-ESI-MS(n)) was developed to identify and characterize the flavonoids in a Chinese formulated preparation, Longdan Xiegan Decoction (LXD). In total, fifty-one flavonoids (27 flavones, 10 flavanones, 7 chalcones, 5 flavonols and 2 isoflavones) were characterized. Eighteen compounds among them including a newly detected flavonoid, naringin, from the ingredient herbs, were unambiguously determined by comparing the retention times (t(R)), UV spectral data and mass fragmentation behaviors with those of the reference compounds. Another thirty-three compounds were tentatively identified by referencing to the reported data of their UV and MS spectra. The ESI-MS/MS fragmentation behavior of flavones (OMe-substituted, O-glycosides, C-glycosides), chalcones, flavonols and their appropriate characteristic pathways were proposed. In negative ion ESI-MS all the flavonoids yielded prominent [M--H](-) ions in the first order mass spectra. Fragmentation with a loss of mass of 15 Da (CH(3)), 18 Da (H(2)O), 28 Da (CO), 44 Da (CO(2)), 56 Da (2CO) and the residues of glucose and glucuronic acid observed in the MS/MS spectra were useful for aiding the structural identification of the flavonoids investigated.

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Section: Experimental Materialsmentioning

confidence: 99%

Section: Chalconesmentioning

confidence: 99%

Characterization of fifty‐one flavonoids in a Chinese herbal prescription Longdan Xiegan Decoction by high‐performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry and photodiode array detection

Wang

Yang

et al. 2008

Rapid Comm Mass Spectrometry

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“…The formation and structures of the [M - H] + ion and [M − H - CO] + ions from the M + , were one focus [9-14], including an ion-structure study with an ion-trap mass spectrometer [15]. Recently, the mechanisms for elimination of C 6 H 6 and CO from the APCI-generated [M + H] + ions of chalcones were established [16].…”

Section: Introductionmentioning

confidence: 99%

Gas-phase nazarov cyclization of protonated 2-methoxy and 2-hydroxychalcone: An example of intramolecular proton-transport catalysis

George

Sebastian

Reddy³

et al. 2009

J. Am. Soc. Mass Spectrom.

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Upon CA, ESI generated [M ϩ H] ϩ ions of chalcone (benzalacetophenone) and 3-phenylindanone both undergo losses of H 2 O, CO, and the elements of benzene. CA of the [M ϩ H] ϩ ions of 2-methoxy and 2-hydroxychalcone, however, prompts instead a dominant loss of ketene. In addition, CA of the [M ϩ H] ϩ ions of 2-methoxy-␤-methylchalcone produces an ␤ analogous loss of methylketene instead. Furthermore, the [M ϩ D] ϩ ion of 2-methoxychalcone upon CA eliminates only unlabeled ketene, and the resultant product, the [M ϩ D Ϫ ketene] ϩ ion, yields only the benzyl-d 1 cation upon CA. We propose that the 2-methoxy and 2-hydroxy (ortho) substituents facilitate a Nazarov cyclization to the corresponding protonated 3-arylindanones by mediating a critical proton transfer. The resultant protonated indanones then undergo a second proton transport catalysis facilitated by the same ortho substituents producing intermediates that eliminate ketene to yield 2-methoxy-or 2-hydroxyphenylphenyl-methylcarbocations, respectively. The basicity of the ortho substituent is important; for example, replacement of the ortho function with a chloro substituent does not provide an efficient catalyst for the proton transports. The Nazarov cyclization must compete with an alternate cyclization, driven by the protonated carbonyl group of the chalcone that results in losses of H 2 O and CO. The assisted proton transfer mediated by the ortho substituent shifts the competition in favor of the Nazarov cyclization. The proposed mechanisms for cyclization and fragmentation are supported by high-mass resolving power data, tandem mass spectra, deuterium labeling, and molecular orbital calculations. T he acid-catalyzed cyclization of divinyl ketones to yield cyclopentenones is known as Nazarov cyclization, a reaction that was recently reviewed [1,2]. Bronsted acids, superacids, and Lewis acids are usually needed to promote the cyclizations in solution. The mechanism involves conrotatory electrocyclic ring closure of a protonated divinyl ketone followed by deprotonation and double-bond reorganization [2]. A general and efficient method for the synthesis of biologically active 3-aryl-indanones is the Nazarov cyclization of substituted chalcones [3][4][5][6]. A variety of indanone derivatives can be synthesized by the microwave-assisted Nazarov cyclization of chalcones in trifluoroacetic acid (TFA) solution [5]. In addition, further motivation comes from the antimicrobial activity of substituted chalcones, which was evaluated recently [7].Characterization of these materials has attracted the attention of mass spectrometrists since the early 1960s , were one focus [9 -14], including an ion-structure study with an iontrap mass spectrometer [15]. Recently, the mechanisms for elimination of C 6 H 6 and CO from the atmospheric pressure chemical ionization (APCI)-generated [M ϩ H] ϩ ions of chalcones were established [16]. Three important product ions observed in the CAD mass spectrum of protonated chalcone arise from losses of H 2 O, CO, and C 6 H 6 . Studie...

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“…Previous researches on the mass spectrometric behaviour of flavonoids (in particular on flavones 1 , flavanones 2 , naphtoflavones 3 and chalconoids 4,5 ) led us to describe new fragmentation processes and some decomposition mechanisms different from those previously suggested. [6][7][8][9][10][11][12] In particular, in the case of chalcone (1) and some of its derivatives, structure a of Scheme 1 for the [MÀH] species was proved on the basis of metastable ion studies, collisional experiments and 2 H and 13 C-labelled compounds.…”

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confidence: 99%

An unexpected methyl loss observed in electron ionization of chalcones

Ardanaz

Kavka

Guidugli

et al. 1998

Rapid Commun. Mass Spectrom.

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A careful analysis of the electron ionization mass spectra of chalcones reveals the presence of [MÀ15]Á and [MÀ16] ions which, by collision experiments, accurate mass measurements and deuterium labelling have been proved to originate by primary methyl and methane loss respectively. These findings suggest the existence of a population of molecular ions of chalcone exhibiting a structure different from the dibenzocycloheptadienone structure proposed in the literature. # 1998 John Wiley & Sons, Ltd. Received 30 October 1997; Revised 1 December 1997; Accepted 2 December 1997 Rapid Commun. Mass Spectrom. 12, 139-143 (1998 Previous researches on the mass spectrometric behaviour of flavonoids (in particular on flavones 1 , flavanones 2 , naphtoflavones 3 and chalconoids 4,5 ) led us to describe new fragmentation processes and some decomposition mechanisms different from those previously suggested. [6][7][8][9][10][11][12] In particular, in the case of chalcone (1) and some of its derivatives, structure a of Scheme 1 for the [MÀH] species was proved on the basis of metastable ion studies, collisional experiments and 2 H and 13 C-labelled compounds. The presence of this tricyclic structure, containing a sevenmembered ring, was confirmed in most of the flavonoids investigated.In the present paper we report further investigations on some EI-generated fragments of chalcone which, though scarcely abundant, represent interesting decomposition products because they provide an indication of M Á and [MÀH] ions of chalcone with a structure different from those already proposed. EXPERIMENTALMass spectrometric measurements were performed using a MAT112S (Varian MAT, Bremen, Germany) magnetic sector instrument and an ITMS (Finnigan MAT, San José, CA, USA) ion trap instrument.In the former case an ionization energy of 70 eV (700 mA) was employed, with an ion source temperature of 200°C and a direct sample inlet temperature between 130 and 150°C. For high resolution measurements, peak matching was used with a precision of 20 ppm and a resolution better than 6000 in the 10% valley definition. For the measurements of all deuterated species, the ion source was always carefully equilibrated with deuterium oxide. The absolute pressure was lower than 5 Â 10 À6 Torr (1 Torr = 133.3 Pa). The ITMS was operated 13 at a fundamental RF drive frequency of 1.1 MHz. Electron impact spectra were generated at an average electron energy of 70 eV. Helium was used as a bath gas at an uncorrected gauge pressure of 1.0 Â 10 À4 Torr. For the analysis of product ions, the precursor ion was selected using the tandem mass spectrometry (MS/MS) scan function and dynamically programmed scans as described previously. 4 Chalcone (1) was synthesized and purified according to the literature. 4 Its purity level (99%) was checked by gas chromatography/mass spectrometry (GC/MS) and the only impurities present were benzaldehyde and acetophenone employed as synthons for 1. RESULTS AND DISCUSSIONThe mass spectrum of chalcone has already been published and its EI-induc...

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On the structure of [C₉H₆O]^+· ions originating by electron impact induced decomposition of chalcone

Cited by 11 publications

References 8 publications

Characterization of fifty‐one flavonoids in a Chinese herbal prescription Longdan Xiegan Decoction by high‐performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry and photodiode array detection

Characterization of fifty‐one flavonoids in a Chinese herbal prescription Longdan Xiegan Decoction by high‐performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry and photodiode array detection

Gas-phase nazarov cyclization of protonated 2-methoxy and 2-hydroxychalcone: An example of intramolecular proton-transport catalysis

An unexpected methyl loss observed in electron ionization of chalcones

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