@article{SarodnickLinkerHeydenreichetal.2009,
  author    = {Sarodnick, Gerhard and Linker, Torsten and Heydenreich, Matthias and Koch, Andreas and Starke, Ines and F{\"u}rstenberg, Sylvia and Kleinpeter, Erich},
  title     = {Quinoxalines XV : convenient synthesis and structural study of pyrazolo[1,5-alpha]quinoxalines},
  issn      = {0022-3263},
  doi       = {10.1021/Jo802398g},
  year      = {2009},
  abstract  = {A series of aryloxymethylquinoxaline oximes, hitherto unknown and synthesized from the corresponding aldehydes, afforded in only one step pyrazolo[1,5-;]quinoxalines in the presence of acetic anhydride at high temperatures. A formal [3,5]-sigmatropic rearrangement was proposed as the mechanistic rationale for this unprecedented transformation. Saponification with potassium hydroxide furnished the free phenol derivatives which were studied by NMR spectroscopy and accompanying theoretical DFT calculations, establishing intramolecular hydrogen bonding and the spatial magnetic properties. Additionally, mass spectrometric fragmentation was investigated by B/E-linked scans and collision-induced dissociation experiments. The fragmentation pattern devoted a new gas phase rearrangement process, which proved to be unique and characteristic for pyrazolo[1,5-;]quinoxalines.},
  language  = {en}
}
@article{StarkeFuerstenbergMuelleretal.2006,
  author    = {Starke, Ines and F{\"u}rstenberg, Sylvia and M{\"u}ller, Holger and Holdt, Hans-J{\"u}rgen and Kleinpeter, Erich},
  title     = {Electrospray mass spectrometric studies of the complexational behavior of maleonitrile thiacrown ethers with various metals},
  doi       = {10.1002/Rcm.2384},
  year      = {2006},
  abstract  = {Electrospray ionization was employed to study the mass spectrometric behavior of the maleonitrile tetrathiacrown ethers mn12S(4) (1) and mn13S(4) (2) and maleonitrile pentathiacrown ether mn15S(5) (3) and of their complexes with various metal salts (MX2, M=Pd, Pt, Ni, Co, Fe; X=Cl, CrCl3, Ni(BF4)(2), TIPF6 or Cd(NO3)(2)) and Cu(SO3CF3)(2). Both singly charged, [MXL](+) and [MXL2]+, and doubly charged complexes, [MLn](2+) (n = 2-5), were observed. The formation of the different complexes consisting of the transition metal ion, the counterion and the various crown ethers and their subsequent dissociation was also studied by collision-induced dissociation measurements which were also used to evaluate the relative stabilities of the complexes. It was found that the collisional voltages for the dissociation of the complexes were generally greater in the [MXL](+) complexes than in the corresponding [MXL2]+ complexes. Copyright (c) 2006 John Wiley \& Sons, Ltd},
  language  = {en}
}