In:
Canadian Journal of Chemistry, Canadian Science Publishing, Vol. 57, No. 15 ( 1979-08-01), p. 2052-2057
Abstract:
The trifluoroacetyl derivatives of the 2,5-diketopiperazines cyclo-(-Val-Val/Leu/Ile), cyclo-(-Leu-Leu/Ile), and cyclo-(-Ile-Ile) were examined by GC–MS. The fragmentation of these compounds generally follows the same pathways as previously observed for the TFA-cyclo-(-Gly-X) series (X = Gly, Val, Leu, Ile). However, the spectra can be interpreted on the basis that the molecular ion fragments prior to, or after, one of the alkyl groups is eliminated as olefin. Some ion fragments indicate that both alkyl groups are eliminated but this does not appear to occur directly from the molecular ion. Support for fragmentation of the molecular ion by the suggested route is indicated by a number of isobaric ions although corresponding metastable ions were not observed.The spectra enable the compounds in the series TFA-cyclo-(-Val-X) (X = Val, Leu, Ile) to be readily identified but this is not the case for TFA-cyclo-(-Leu-Leu/Ile) and TFA-cyclo-(-Ile-Ile). However, all of these compounds can be distinguished from TFA-cyclo-(-Gly-X) and TFA-cyclo-(-Ala-X) (X = Gly, Val, Leu, Ile).
Type of Medium:
Online Resource
ISSN:
0008-4042
,
1480-3291
Language:
English
Publisher:
Canadian Science Publishing
Publication Date:
1979
detail.hit.zdb_id:
1482256-8
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