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Electron impact induced rearrangement processes for some 1‐trimethylsilyl‐2‐methoxycarbonyl‐3‐alkyl‐Δ 1–3 ‐cyclopropenes
Author(s) -
Vékeym Károly,
Tamás József,
Okonnishnikova Galina P.,
Dolgy Igor E.,
Nefedov Oleg M.
Publication year - 1981
Publication title -
organic mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0030-493X
DOI - 10.1002/oms.1210160505
Subject(s) - chemistry , cyclopropene , intramolecular force , trimethylsilyl , alkyl , dissociation (chemistry) , fragmentation (computing) , electron ionization , medicinal chemistry , molecule , ring (chemistry) , photochemistry , stereochemistry , computational chemistry , ion , organic chemistry , computer science , ionization , operating system
The electron impact induced decomposition of five of the title compounds with methyl, ethyl, n ‐propyl, n ‐butyl or n ‐pentyl groups, has been investigated in detail. The observed fragmentation can be characterized by two outstanding features: (a) interactions of the silicon centre with the ethereal oxygen atom of the methoxy carbonyl group, (b) strong directing effects of the cyclopropene ring. As a consequence of (a), the loss of a (CH 3 ) 3 SiOCH 3 molecule represents the main decomposition pathway of the molecular ion. It was shown to be a low energy, single dissociation step reaction, not depending on the radical site or charge localization. In spite of the rigid skeleton, ring opening does not take place during this process. As to (b), beside the β‐fission, highly selective and intense δ‐ and ϵ‐cleavages of the alkyl chain have been observed following the (CH 3 ) 3 SiOCH 3 elimination. On the basis of energetic and kinetic considerations, these interesting reactions can be rationalized in terms of through‐space interactions and intramolecular ortho substitution (cyclization) processes.