Differentiation of diastereomeric conduramine derivatives under electron ionization and chemical ionization mass spectral conditions

Ramanjaneyulu, G.; Prabhakar, S.; Bhaskar, G.; Vairamani, M.; Yadav, J. S.; Murty, V.S.; Soujanya, Yarasi; Sastry, G. Narahari

doi:10.1002/rcm.2865

Cited by 6 publications

(5 citation statements)

References 18 publications

(28 reference statements)

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“…Mass spectrometry is a proven tool in the analysis of stereoisomers employing a wide range of ionization and tandem mass spectrometric techniques 14–16. We have reported the differentiation of several diastereomeric compounds using electron ionization (EI), chemical ionization (CI) and electrospray ionization (ESI) 17, 18. As part of our ongoing research, we have undertaken a detailed mass spectrometric analysis of the isomeric precursors 1 – 4 (Scheme ).…”

Section: Methodsmentioning

confidence: 99%

Differentiation of the diastereomeric synthetic precursors of isofebrifugine and febrifugine by electrospray ionization tandem mass spectrometry

Ramanjaneyulu¹,

Sudhakar²,

Rao³

et al. 2008

Rapid Comm Mass Spectrometry

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Febrifugine is an alkaloid with potent antimalarial activity isolated from Dichroa febrifuga and Hydrangea umbellate, and it exists naturally with its diastereomeric component, isofebrifugine. Here we report the differentiation of diastereomeric synthetic precursors of isofebrifugine (1, cis) and febrifugine (2, trans) and a structurally similar model diastereomeric pair without a halogen substituent (3 and 4) by electrospray ionization (ESI) tandem mass spectrometry. Compounds 1-4 contain a tert-butoxycarbonyl (BOC) substituent, and the collision-induced dissociation (CID) spectra of the [M+H](+), [M+Na](+) and [M+Li](+) ions of 1-4 include the expected product ions corresponding to the loss of C(4)H(8) (isobutene) and of C(5)H(8)O(2) (BOC-H). Loss of C(5)H(8)O(2) is dominant in cis isomers (1 and 3) and/or loss of C(4)H(8) ions is dominant in trans isomers (2 and 4). The decomposition of [M+H](+) ions shows stereoselectivity in the formation of the [M+H-(BOC-H)-C(3)H(5)OBr](+) and [M+H-(BOC-H)-C(6)H(5)CH(2)OH](+) ions. The [M+Cat](+) ions (where Cat = Na or Li) additionally show loss of NaBr and HBr from [M+Cat-(BOC-H)](+), and these product ions are constantly more abundant in cis isomers than in trans isomers. The stereoselectivity for the product ion corresponding to the loss of [(BOC-H)+C(3)H(5)OBr] from [M+H](+) ions differs from that from [M+Cat](+) ions.

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Section: Methodsmentioning

confidence: 99%

Differentiation of the diastereomeric synthetic precursors of isofebrifugine and febrifugine by electrospray ionization tandem mass spectrometry

Ramanjaneyulu¹,

Sudhakar²,

Rao³

et al. 2008

Rapid Comm Mass Spectrometry

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“…The spectra of compounds 1-22 showed a dominant [M-C 4 H 8 ] +. ion formed by the retro-Diels-Alder (RDA) [15] reaction. The other fragment ions were [M-CH 3 (Tables 1 and 2).…”

Section: Electron Ionizationmentioning

confidence: 99%

“…To the best of our knowledge, there are no reports on the differentiation of these isomeric dimethyl tetrahydroquinolines by mass spectrometry. As a part of our on-going research on differentiation of isomeric compounds (structural and stereoisomers), [15][16][17][18] we have undertaken a detailed investigation of the differentiation of isomeric 2-aryldimethyltetrahydro-5-quinolinones using EI and ESI techniques and the results are presented here.…”

mentioning

confidence: 99%

Differentiation of isomeric 2‐aryldimethyltetrahydro‐5‐quinolinones by electron ionization and electrospray ionization mass spectrometry

Kumar

Chary

Dinesh

et al. 2011

Rapid Comm Mass Spectrometry

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A series of isomeric 2-aryl-6,6-dimethyltetrahydro-5-quinolinones (set I) and 2-aryl-7,7-dimethyltetrahydro-5-quinolinones (set II) were studied under positive ion electron ionization (EI) and electrospray ionization (ESI) techniques. Under EI conditions, the molecular ions were found to be less stable in set I isomers, and they resulted in abundant fragment ions, i.e., [M-CH(3)](+), [M-CO](+.), [M-HCO](+), [M-(CH(3),CO)](+), and [M-(CH(3),CH(2)O)](+), when compared with set II isomers. In addition, the set I isomers showed specific fragment ions corresponding to [M-OH](+) and [M-OCH(3)](+). The retro-Diels-Alder (RDA) product ion was always higher in set II isomers. The ESI mass spectra produced [M + H](+) ions, and their decomposition showed favorable loss of CH(3) radical, CH(4) and C(2)H(6) molecules in set I isomers. The set II isomers, however, showed predominant RDA product ions, and specific loss of H(2)O. The selectivity in EI and ESI was attributed to the instability of set I isomers by the presence of a gem-dimethyl group at the α-position, and it was supported by the data from model compounds without a gem-dimethyl group. Density functional theory (DFT) calculations successfully corroborated the fragmentation pathways for diagnostic ions. This study revealed the effect of a gem-dimethyl group located at the α-position to the carbonyl having aromatic/unsaturated carbon on the other side of the carbonyl group.

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“…As a continuation of this work, Prabhakar et al at IICT addressed the differentiation of diastereomers of biological or synthetic importance, such as hydroxy brevicomins, conduramine derivatives, precursors of febrifugene/ isofebrifugene and a-sulfanyl b-amino acid derivatives. [93][94][95][96][97] A few sets of structural isomers, substituted diaryl ethers and benzoxazolinones, were also differentiated. 98,99 Prabhakar and colleagues demonstrated the occurrence of EI-induced Claisen rearrangements and Newman-Kwart rearrangements with the aid of high-resolution mass spectrometry (HRMS) and MS/MS.…”

Section: Introductionmentioning

confidence: 99%

Mass Spectrometry in India

Vairamani

Prabhakar

2012

Eur J Mass Spectrom (Chichester)

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All rights reserved EUROPEAN JOURNAL OF MASS SPECTROMETRY This review highlights the research in mass spectrometry carried out all over India, with a focus on the last two decades. There has been a phenomenal increase in the use of mass spectrometers in India during the last decade following the introduction, at the beginning of the 21st century, of rugged electrospray ionization sources for the commercially available instruments, with applications such as pharmacokinetics and bio-equivalence drug studies, pesticide residue analysis and proteomics. There have been more papers published in these areas than could be fully covered in this article. This review covers mostly research in mass spectrometry carried out continuously in institutions where advanced facilities for mass spectrometry are functional. Researchers in India, with some notable exceptions, have always used and still use commercial mass spectrometers in their various areas of research, rather than develop their unique instruments. The review is divided into three parts: organic, elemental (or atomic) and biological mass spectrometry. Organic mass spectrometry Organic and bio-organic chemistry Research in organic mass spectrometry in the early years was mainly focused on the study of mass spectral fragmentation of different classes of new compounds,and was initiated in the 1960s by the late Das and his colleagues from the National Chemical Laboratory (NCL), Pune. The first double-focusing mass spectrometer (CEC-110 B) was installed at NCL for high-resolution mass measurements. The compounds studied by Das and his colleagues included aromatic amides, Benzophenanthridine derivatives, norses

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Differentiation of diastereomeric conduramine derivatives under electron ionization and chemical ionization mass spectral conditions

Cited by 6 publications

References 18 publications

Differentiation of the diastereomeric synthetic precursors of isofebrifugine and febrifugine by electrospray ionization tandem mass spectrometry

Differentiation of the diastereomeric synthetic precursors of isofebrifugine and febrifugine by electrospray ionization tandem mass spectrometry

Differentiation of isomeric 2‐aryldimethyltetrahydro‐5‐quinolinones by electron ionization and electrospray ionization mass spectrometry

Mass Spectrometry in India

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