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

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 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.

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

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.

scholarly journals Mass Spectrometric Studies of Dehydro-α-lapachone and Dehydro-iso-α-lapachone

1973 ◽  
Vol 28 (11-12) ◽  
pp. 646-649 ◽  
Author(s):  
Krishna C. Joshi ◽  
Lalit Prakash ◽  
R. K. Bansal ◽  
Pahup Singh
Keyword(s):  
Mass Spectrometric ◽  
Mass Spectral Fragmentation ◽  
Mass Spectral ◽  
Tabebuia Rosea ◽  
Fragmentation Patterns

Abstract Mass spectral fragmentation studies of dehydro-a-lapachone and dehydro-iso-a-lapadione, isolated from the heartwood of Tabebuia rosea, have been made. The fragmentation patterns in the case of two compounds are essentially similar and have been discussed

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