Journal ArticleDOI
The Claisen rearrangement of protonated allyl phenyl ether
E. E. Kingston,John H. Beynon,Joachim G. Liehr,Philippe Meyrant,Robert Flammang,André Maquestiau +5 more
TLDR
In this paper, collision-induced dissociation spectra were used to verify the structures of the daughter ions and a mechanism for the ethene loss was proposed, together with other evidence of acid-induced ortho rearrangement.Abstract:
Molecular protonated ions of allyl phenyl ether undergo a Claisen rearrangement both in the ion source and along the flight path. The rearranged ions undergo fragmentation, the predominat loss being ethene, and only a small contribution from loss of carbon monoxide is observed. Collision-induced dissociation spectra are used to verify the structures of the daughter ions. These spectra, together with other evidence of an acid-induced ortho rearrangement, allow a mechanism to be proposed for the ethene loss. In contrast, molecular protonated ions of propargyl phenyl ether lose exclusively carbon monoxide.read more
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Gas-phase nazarov cyclization of protonated 2-methoxy and 2-hydroxychalcone: An example of intramolecular proton-transport catalysis
M. George,Valarkottu S. Sebastian,Putluri Nagi Reddy,Ragampeta Srinivas,Daryl Giblin,Michael L. Gross +5 more
TL;DR: It is proposed that the 2-methoxy and 2-hydroxy (ortho) substituents facilitate a Nazarov cyclization to the corresponding protonated 3-aryl-indanones by mediating a critical proton transfer, supported by high-mass resolving power data, tandem mass spectra, deuterium labeling, and molecular orbital calculations.
Journal ArticleDOI
Quinoxalines XV. Convenient synthesis and structural study of pyrazolo[1,5-a]quinoxalines.
Gerhard Sarodnick,Torsten Linker,Matthias Heydenreich,Andreas Koch,Ines Starke,Sylvia Fürstenberg,Erich Kleinpeter +6 more
TL;DR: A series of aryloxymethylquinoxaline oximes, hitherto unknown and synthesized from the corresponding aldehydes, afforded in only one step pyrazolo[1,5-a]quinoxalines in the presence of acetic anhydride at high temperatures.
Journal ArticleDOI
Gas Phase Decarbonylation and Cyclization Reactions of Protonated N-Methyl-N-Phenylmethacrylamide and Its Derivatives Via an Amide Claisen Rearrangement
TL;DR: Mechanisms for the gas phase decarbonylation and cyclization reactions of protonated N-methyl-N-phenylmethacrylamide and its derivatives were proposed based on the accurate m/z measurements and MS/MS experiments with deuterated compounds and the influence of different phenyl substituents was evaluated.
Journal ArticleDOI
Mass spectral fragmentation pathways of propranolol related β-fluorinated amines studied by electrospray and electron impact ionization
TL;DR: The changes observed in apparent molecular sites of protonation and of ion radical formation in the mass spectra are consistent with the electron-withdrawing effects of the sequentially added fluorines.
Journal ArticleDOI
Claisen rearrangements and cyclisations in phenyl propargyl ethers under electron impact conditions
TL;DR: In this paper, an interesting Claisen rearrangement has been observed in phenyl propargyl ether, yielding significant amounts of the [M − CO] ion under electron impact conditions.
References
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Intramolecular hydrogen transfer in mass spectra. II. McLafferty rearrangement and related reactions
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Intramolecular hydrogen transfer in mass spectra. I. Rearrangements in aliphatic hydrocarbons and aromatic compounds
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