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Cyclization of molecular ions: The mass spectrometric fragmentation of allene‐carboxylic esters
Author(s) -
Liehr J. G.,
Runge W.,
Richter W. J.
Publication year - 1972
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.1210060805
Subject(s) - allene , chemistry , fragmentation (computing) , ion , mass spectrum , polyatomic ion , electron ionization , mass spectrometry , alkyl , bond cleavage , ionization , medicinal chemistry , chemical ionization , stereochemistry , photochemistry , organic chemistry , catalysis , chromatography , computer science , operating system
A series of six 2,4,4‐substituted allenecarboxylic esters R 1 R 2 CCC(R 3 )COOAlk has been found to exhibit O‐Alkyl cleavage as the most prominent feature of both their 70 and 12 eV mass spectra. Loss of linearity of the allene system upon ionization, followed by conversion of the molecular ion to a 5‐membered cyclic isomer, is thought to induce this unusual mode of bond rupture. Oxygen‐migration from the ester function to C‐4 as is indicated by the subsequent decomposition of the [M — Alk] ions to [R 1 CO]+ and [R 2 CO] + fragments can be taken as direct evidence in favour of this rationale.