On the generation and characterization of the spiro[2,5]octadienyl anion in the gas phase
摘要:
AbstractThree routes have been explored in both a high‐pressure chemical ionization (CI) source and a low‐pressure Fourier transform ion cyclotron resonance (FT‐ICR) cell to generate the spiro[2,5]octadienyl anion in the gas phase: (i) proton abstraction from spiro[2,5]octa‐4,6‐diene; (ii) expulsion of trimethysilyl fluoride by phenyl ring participation following fluoride anion attack upon the silicon centre of 2‐phenylethyl trimethylsilane; and (iii) collisionally induced dissociation (CID) of the carboxylate anion of 3‐phenylpropanoic acid via carbon dioxide loss. From comparison of the CID spectra of various reference [C8H9]− ions with those of the [C8H9]− ions which could be generated via the routes (i) and (iii) in the CI source it can be concluded that only the third route yields a [C8H9]−ion whose CID spectrum is not inconsistent with the one expected for the spiro[2,5]octadienyl anion. In the FT‐ICR cell [C8H9]− ions are generated along all three routes; their structures have been identified by specific ion‐molecule reactions and appear to be different. Route (i) yields an α‐methyl benzyl anion, probably due to isomerization within the ion‐molecule complex formed. An ortho‐ethylphenyl anion is formed along route (ii), presumably due to an intramolecular ortho proton abstraction in the generated trimethylsilyl fluoride solvated 2‐phenylethyl primary carbanion. The [C8H9]− ion formed along route (iii) shows reactions similar to those of the 1,1‐dimethylcyclohexadienyl anion which is structurally related to the spiro[2,5]octadienyl anion. Furthermore, the [C8H9]− ion generated via route (iii) reacts with hexafluorobenzene under expulsion of only one hydrogen fluoride molecule which contains exclusively one of the original phenyl ring hydrogen atoms. On the basis of all these observations it is therefore quite likely that the spiro[2,5]octadienyl anion is formed by collisionally induced decarboxylation of the 3‐phenylpropanoic acid carboxylate anion and can be a long‐lived and stable species in the gas phase.
On the generation and characterization of the spiro[2,5]octadienyl anion in the gas phase
摘要:
AbstractThree routes have been explored in both a high‐pressure chemical ionization (CI) source and a low‐pressure Fourier transform ion cyclotron resonance (FT‐ICR) cell to generate the spiro[2,5]octadienyl anion in the gas phase: (i) proton abstraction from spiro[2,5]octa‐4,6‐diene; (ii) expulsion of trimethysilyl fluoride by phenyl ring participation following fluoride anion attack upon the silicon centre of 2‐phenylethyl trimethylsilane; and (iii) collisionally induced dissociation (CID) of the carboxylate anion of 3‐phenylpropanoic acid via carbon dioxide loss. From comparison of the CID spectra of various reference [C8H9]− ions with those of the [C8H9]− ions which could be generated via the routes (i) and (iii) in the CI source it can be concluded that only the third route yields a [C8H9]−ion whose CID spectrum is not inconsistent with the one expected for the spiro[2,5]octadienyl anion. In the FT‐ICR cell [C8H9]− ions are generated along all three routes; their structures have been identified by specific ion‐molecule reactions and appear to be different. Route (i) yields an α‐methyl benzyl anion, probably due to isomerization within the ion‐molecule complex formed. An ortho‐ethylphenyl anion is formed along route (ii), presumably due to an intramolecular ortho proton abstraction in the generated trimethylsilyl fluoride solvated 2‐phenylethyl primary carbanion. The [C8H9]− ion formed along route (iii) shows reactions similar to those of the 1,1‐dimethylcyclohexadienyl anion which is structurally related to the spiro[2,5]octadienyl anion. Furthermore, the [C8H9]− ion generated via route (iii) reacts with hexafluorobenzene under expulsion of only one hydrogen fluoride molecule which contains exclusively one of the original phenyl ring hydrogen atoms. On the basis of all these observations it is therefore quite likely that the spiro[2,5]octadienyl anion is formed by collisionally induced decarboxylation of the 3‐phenylpropanoic acid carboxylate anion and can be a long‐lived and stable species in the gas phase.
The synthesis of [phenyl-2H5]gluconasturtiin and its metabolites for metabolic studies
作者:John J. Morrison、Nigel P. Botting
DOI:10.1002/jlcr.1004
日期:2005.10.30
The synthesis of a deuterium labelled glucosinolate, [2H5]gluconasturtiin, is described starting from [2H5]bromobenzene. The potential metabolites of the glucosinolate, namely the [phenyl-2H5]phenethyl isothiocyanate, nitrile, thiocyanate, amine and the mercapturic acid conjugate of phenethyl isothiocyanate are also described. This series of compounds has been prepared for use in feeding studies to
Intramolecular ring-to-ring proton transfer in gaseous (.omega.-phenylalkyl)benzenium ions
作者:Dietmar Kuck、Wolfgang Baether、Hans Friedrich Gruetzmacher
DOI:10.1021/ja00518a004
日期:1979.11
corresponding 1 -(a-phenylalkyl)- 1,4-dihydrobenzoic acids 4 and 5. The major secondary fragmentation is loss of benzene from 1 and 2. It is shown by deuterium labeling that 1 and 2 ions undergo repeated ring-to-ring proton transferreactions, equilibrating all of the 11 "aromatic" hydrogenatoms within s without involving those from the aliphatic chain. A competition between the ring-to-ring (quasi-intermolecular)