Zum Mechanismus massenspektrometrischer Fragmentierungsreaktionen.—I Methoxygruppenwanderungen in den Massenspektren der Methyläther von linearen und verzweigten aliphatischen Polyalkoholen

Abstract

Abstract-The formation of 1 ,l-dimethoxy-alkyl rearrangement ions in the mass spectra of methyl ethers of linear diols, 1,2,3-trioIs and of derivatives of pentaglycerol and pentaerythritol has been investigated by deuterium labelling and mass measurements. Methoxy group migrations do not occur, or at least only to a small amount, in the mass spectra of the diol-dimethyl ethers. The mass spectra of methyl ethers of 1,2,3-triols exhibit characteristic peaks of the rearrangement ions +CH(OCH,)B and +CR(OCH3)z. These ions arise by a 1,3-migration of a methoxy group, probably during a one step degradation of the molecular ion to give a molecule methyl alkenyl ether and a H-atom or alkyl radical as neutral fragments. Large peaks of the rearrangement ion +CH(OCH& are observed in the mass spectra of compounds of the following type:

Transition metal catalyzed valence isomerizations of tricyclo[4.1.0.02,7]heptane. Evidence for an organometallic intermediate

“…Using freshly prepared and recrystallized [Rh(CO)2-Cl]210 in methanol,11 bicyclobutane 1 gives better than (8) Reactions were analyzed by nmr spectroscopy. (9) The reaction of dienes with Pd(II) is well known to give -allyl complexes. See ref 6.…”