Mass Spectra of β-Keto Esters

1972 ◽  
Vol 50 (16) ◽  
pp. 2707-2710 ◽  
Author(s):  
Larry Weiler
Keyword(s):  
Mass Spectra ◽  
Carbonyl Groups ◽  
Mass Spectral Fragmentation ◽  
Mass Spectral ◽  
Keto Esters ◽  
Fragmentation Patterns

The mass spectra of several γ-substituted β-keto esters have been recorded and interpreted. The fragmentation patterns are compared to those of α-substituted β-keto esters and are found to be very useful in differentiating the α- and γ-substituted isomers. The mass spectral fragmentation schemes are dominated by cleavages α to the carbonyl groups and by McLafferty rearrangements.

scholarly journals Mass spectra of bis(trimethylsilyl)- and bis(trimethylgermyl)carbodiimide

1979 ◽  
Vol 57 (10) ◽  
pp. 1162-1166 ◽  
Author(s):  
John E. Drake ◽  
Boris M. Glavinčevski ◽  
H. Ernest Henderson ◽  
Clara Wong
Keyword(s):  
Mass Spectra ◽  
Mass Spectral Fragmentation ◽  
Fragmentation Pathways ◽  
Mass Spectral ◽  
Fragmentation Patterns

The mass spectral fragmentation patterns of bis(trimethylsilyl)- and bis(trimethylgermyl)carbodiimides are compared. Metastable confirmed transitions involve elimination of neutral fragments apparently containing Si=N and/or Si=C bonds. The fragmentation pathways are similar for the germyl analogue but no proof of a fragment containing a Ge=C bond was observed.

Triazolopyridine nucleosides. II. Glycosylations of 3-oxo-s-triazolo[4,3-a]pyridines with accompanying conversions into 2-oxo-s-triazolo[1,5-a]pyridine nucleosides

1977 ◽  
Vol 55 (5) ◽  
pp. 831-840 ◽  
Author(s):  
Brian Maurice Lynch ◽  
Suresh Chandra Sharma
Keyword(s):  
General Structure ◽  
Spectroscopic Properties ◽  
Mass Spectral Fragmentation ◽  
Mass Spectral ◽  
H Nmr ◽  
Pyridine Nitrogen ◽  
Methyl Derivatives ◽  
Fragmentation Patterns ◽  
Ribose Moiety ◽  
C Nmr

3-Oxo-s-triazolo[4,3-a]pyridine and various C-methyl derivatives (general structure 1) have been converted into the 2-β-D-ribofuranosyl species 2 and thence 4 via Friedel–Crafts catalyzed reaction with tetra-O-acetyl-β-D-ribofuranose, followed by deblocking. During the course of these reactions, rearrangements into the isomeric 3-β-D-ribofuranosyl-2-oxo-s-triazolo[1,5-a]-pyridines occur through ring-opening of the pyridine rings yielding species 3 and 5. The proportion of rearrangement products is dependent upon the position and number of the C-methyl substituents.Structural assignments for these compounds are based upon comparisons of spectroscopic properties (1H nmr, 13C nmr, uv) with model compounds from each isomeric series; structural assignments for these models are based on unequivocal mass-spectral fragmentation patterns. Unlike related triazolopyridine nucleosides with the ribose moiety attached to a pyridine nitrogen (Lynch and Sharma (1976)), there are no unusual aspects in the conformations of the nueleosides of types 4 and 5.

Mass spectral fragmentation patterns of some 2-methyl-3-furancarboxanilides and 2-methyl-3-furancarbothioanilides. II

1995 ◽  
Vol 9 (9) ◽  
pp. 778-780 ◽  
Author(s):  
Grace Karminski-Zamola ◽  
Lelja Fi??er-Jakić ◽  
Miroslav Bajić And ◽  
David W. Boykin
Keyword(s):  
Mass Spectral Fragmentation ◽  
Mass Spectral ◽  
Fragmentation Patterns

Mass Spectral Fragmentation Patterns of 3,6-Dihydro-1,2-oxazines

Heterocycles ◽  
1990 ◽  
Vol 31 (6) ◽  
pp. 1021
Author(s):  
Henryk Labaziewicz ◽  
Kenryk Labaziewicz ◽  
Robert E. Kohrman ◽  
Bob A. Howell
Keyword(s):  
Mass Spectral Fragmentation ◽  
Mass Spectral ◽  
Fragmentation Patterns

Mass Spectra of Some Carbamates and Related Ureas. II

1968 ◽  
Vol 51 (2) ◽  
pp. 347-365 ◽  
Author(s):  
W R Benson ◽  
J N Damico
Keyword(s):  
Spectral Data ◽  
Relative Abundance ◽  
Mass Spectra ◽  
The Other ◽  
Methyl Isocyanate ◽  
Mass Spectral Data ◽  
Mass Spectral ◽  
Fragmentation Patterns ◽  
Sulfur Containing

Abstract Mass spectral data for fourteen carbamates, live dithiocarbamates, one thiocarbamate, and eight phenylureas are given with some interpretations. Among the compounds examined were some sulfur-containing aliphatic oxime carbamates; these lost the sulfur moieties more easily than the methyl isocyanate moiety. In the aryl IV-methylcarbamate series, the CH3NCO moiety appears to be lost most easily, as it is in pyrolysis. When l-(2-chlorophenyI)-3- methylurea is fragmented, unexpectedly the [HNC0]+ ion is found in high relative abundance. However, the remaining ureas undergo fragmentation in a manner similar to their related carbamates. Although the two ethylene bisdithiocarbamates give essentially identical fragmentation patterns, the spectra of the other four thio- and dithiocarbamates show sufficient differences so that they may be distinguished from one another.

scholarly journals Mass Spectral Fragmentation Pattern of Ν,N′ -Diphenylformamidines

1977 ◽  
Vol 32 (10) ◽  
pp. 1156-1159 ◽  
Author(s):  
Neil G. Keats ◽  
Jean E. Rockley ◽  
Lindsay A. Summers
Keyword(s):  
Mass Spectra ◽  
Molecular Ions ◽  
Fragmentation Pattern ◽  
Mass Spectral Fragmentation ◽  
Mass Spectral ◽  
Hydrogen Migration ◽  
Mass Spectral Fragmentation Pattern

The base peaks in the mass spectra of Ν,N′-diphenylformamidine, N,N′-di-(4-chlorophenyl)formamidine and N,N′-di-(3-chlorophenyl)formamidine are due to the molecular ions of aniline, 4-chloroaniline and 3-chloroaniline respectively. The species responsible for the base peaks are thought to be formed by rupture of the CH-NH bond with concomitant hydrogen migration.

Massenspektrometrische Fragmentierung von Trimethylsilylderivaten (TMS) des Thyrotropin-„Releasing“-Hormons (TRH) und dessen Teilstrukturen / Mass Spectroscopy of Trimethylsilyl Derivatives of Thyrotropin-releasing Hormone and its Constituents

1973 ◽  
Vol 28 (11-12) ◽  
pp. 820-823 ◽  
Author(s):  
W. A. König ◽  
S. Fuchs ◽  
K. Zech ◽  
W. Voelter
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectroscopy ◽  
Peptide Hormones ◽  
Thyrotropin Releasing Hormone ◽  
Mass Spectral Fragmentation ◽  
Releasing Hormone ◽  
Mass Spectral ◽  
Trimethylsilyl Derivatives ◽  
Fragmentation Patterns ◽  
Derivatives Of

The mass spectral fragmentation patterns of trimethylsilyl derivatives of TRH and its constituents are discussed. The utility of these derivatives for the control of the synthesis of peptide hormones by mass spectrometry is obvious.

Sign in / Sign up

Export Citation Format

Share Document