Mass spectra of some 5-methyl-19-nor-5β-cholest-9-enes

The mass spectrometric behavior of isomeric ketones I-V and alcohols VI-X of Westphalen type is described. The differences in fragmentation patterns of these compounds are discussed in dependence on the position and the configuration of the substituent.

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The mass spectrometric behavior of 3α,5-cyclo-5α-cholestan-6β-yl alkyl ethers

Canadian Journal of Chemistry ◽

10.1139/v80-414 ◽

1980 ◽

Vol 58 (23) ◽

pp. 2592-2599 ◽

Cited By ~ 2

Author(s):

Frederick J. Brown ◽

Ian J. Massey ◽

Carl Djerassi

Keyword(s):

Structure Elucidation ◽

Mass Spectra ◽

Mass Spectrometric ◽

Ring Cleavage ◽

Methyl Ethyl ◽

Deuterium Labeling ◽

Partial Synthesis ◽

Tert Butyl ◽

Alkyl Ethers ◽

Mass Spectrometric Behavior

The 3α,5-cyclo-6β-methoxy (i-methyl ether) moiety is a common protective grouping in steroid partial synthesis. Therefore, the mass spectrometric behavior of 6β-hydroxy-3α,5-cyclo-5α-cholestane, the corresponding methyl, ethyl, and tert-butyl ethers, the analogous ketone, and the parent hydrocarbon has been investigated in order to determine the mechanisms of the characteristic fragmentations of these compounds. Such knowledge is essential for unequivocal structure elucidation by mass spectrometry and also bears on the current interest in the stereospecificity of electron impact induced eliminations. Deuterium labeling of carbon atoms 1,2,3,4,7,8,9, and 19 of 6β-methoxy-3α,5-cyclo-5α-cholestane established the course of methanol extrusion and the identity of the highly diagnostic A ring cleavage ion [Formula: see text] Mechanisms are proposed for these key fragmentations. The mass spectra of the methyl, ethyl, and tert-butyl ethers of cholesterol are analyzed, and the features distinguishing these compounds from the isomeric 3,5-cyclosteroids are noted.

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Rapid Mass Spectrometric Analysis of a Novel Fucoidan, Extracted from the Brown AlgaCoccophora langsdorfii

The Scientific World JOURNAL ◽

10.1155/2014/972450 ◽

2014 ◽

Vol 2014 ◽

pp. 1-9 ◽

Cited By ~ 10

Author(s):

Stanislav D. Anastyuk ◽

Tatyana I. Imbs ◽

Pavel S. Dmitrenok ◽

Tatyana N. Zvyagintseva

Keyword(s):

Mass Spectra ◽

Structural Features ◽

Degree Of Polymerization ◽

Mass Spectrometric ◽

Spectrometric Analysis ◽

Low Molecular Weight ◽

Ionization Mass ◽

The Novel ◽

Fragmentation Patterns ◽

Rapid Mass

The novel highly sulfated (35%) fucoidan fractionCf2, which contained, along with fucose, galactose and traces of xylose and uronic acids was purified from the brown algaCoccophora langsdorfii. Its structural features were predominantly determined (in comparison with fragments of known structure) by a rapid mass spectrometric investigation of the low-molecular-weight fragments, obtained by “mild” (5 mg/mL) and “exhaustive” (maximal concentration) autohydrolysis. Tandem matrix-assisted laser desorption/ionization mass spectra (MALDI-TOF/TOFMS) of fucooligosaccharides with even degree of polymerization (DP), obtained by “mild” autohydrolysis, were the same as that observed for fucoidan fromFucus evanescens, which have a backbone of alternating (1 → 3)- and (1 → 4) linked sulfated at C-2 and sometimes at C-4 of 3-linkedα-L-Fucpresidues. Fragmentation patterns of oligosaccharides with odd DP indicated sulfation at C-2 and at C-4 of (1 → 3) linkedα-L-Fucpresidues on the reducing terminus. Minor sulfation at C-3 was also suggested. The “exhaustive” autohydrolysis allowed us to observe the “mixed” oligosaccharides, built up of fucose/xylose and fucose/galactose. Xylose residues were found to occupy both the reducing and nonreducing termini of FucXyl disaccharides. Nonreducing galactose residues as part of GalFuc disaccharides were found to be linked, possibly, by 2-type of linkage to fucose residues and were found to be sulfated, most likely, at position C-2.

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Benzodiazepine Analogues. Part 20. Mass Spectrometric Analysis of Benzoxathiepine Derivatives

Journal of Chemical Research ◽

10.1177/174751989902300933 ◽

1999 ◽

Vol 23 (9) ◽

pp. 584-585

Author(s):

Aifheli C. Gelebe ◽

Perry T. Kaye

Keyword(s):

High Resolution ◽

Electron Impact ◽

Mass Spectra ◽

Mass Spectrometric ◽

Mass Spectrometric Analysis ◽

Spectrometric Analysis ◽

Low Resolution ◽

Fragmentation Patterns ◽

Resolution Mass

Fragmentation patterns in the electron-impact (El) mass spectra of benzoxathiepine derivatives are elucidated using a combination of high-resolution and comparative low-resolution mass spectrometric analysis.

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Synthesis and Mass Spectral Fragmentation Patterns of Brassinolide Early Biosynthetic Precursors Labeled at C-26

Natural Product Communications ◽

10.1177/1934578x1300800622 ◽

2013 ◽

Vol 8 (6) ◽

pp. 1934578X1300800

Author(s):

Vladimir A. Khripach ◽

Danuše Tarkowská ◽

Vladimir N. Zhabinskii ◽

Olga V. Gulyakevich ◽

Yurii V. Ermolovich ◽

...

Keyword(s):

Mass Spectrometry ◽

Liquid Chromatography ◽

Mass Spectrometric ◽

Keto Group ◽

Liquid Chromatography Mass Spectrometry ◽

Mass Spectral Fragmentation ◽

Mass Spectral ◽

Fragmentation Patterns ◽

Natural Brassinosteroids ◽

Mass Spectrometric Behavior

New analogues of brassinolide biosynthetic precursors with three deuterium atoms at non-exchangeable positions have been synthesized to be used as standards for quantification of natural brassinosteroids by liquid chromatography-mass spectrometry. [26-2H3](22 R,23 R,24 S)-22,23-Dihydroxy-6β-methoxy-24-methyl-3α,5-cyclo-5α-cholestane was used as a starting material for the preparation of campestane derivatives having a 22 R,23 R-diol functionality and either a hydroxy or keto group at C-3 and labeled at C-26. The mass spectrometric behavior of the newly synthesized compounds has been studied.

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The synthesis and mass spectra of some oxygen-bridged 5α-cholestane and B-homo-5α-cholestane derivatives

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19800274 ◽

1980 ◽

Vol 45 (1) ◽

pp. 274-293 ◽

Cited By ~ 2

Author(s):

František Tureček ◽

Pavel Kočovský

Keyword(s):

Mass Spectra ◽

Mass Spectrometric ◽

Oxygen Bridge ◽

Fragmentation Patterns ◽

Steroid Skeleton ◽

Bridge Position

The synthesis and mass spectrometric behaviour of a series of oxygen-bridged α-cholestans and B-homo-5α-cholestans I-X are described. The differences in fragmentation patterns of these compounds are discussed in dependence on the position of the oxygen bridge, position and configuration of additional substituents and conformation of the A and B rings of the steroid skeleton.

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Mass spectrometry of ozonides

Canadian Journal of Chemistry ◽

10.1139/v69-150 ◽

1969 ◽

Vol 47 (6) ◽

pp. 919-934 ◽

Cited By ~ 16

Author(s):

J. Castonguay ◽

M. Bertrand ◽

J. Carles ◽

S. Fliszár ◽

Y. Rousseau

Keyword(s):

Mass Spectrometry ◽

Mass Spectra ◽

Mass Spectrometric ◽

Fragment Ions ◽

Spectrometric Identification ◽

Mass Spectrometric Identification ◽

Fragmentation Patterns

The mass spectra of some ozonides are reported, and the modes of formation of the major fragment ions tentatively described. The use of 18O-labelled compounds has proven to be useful in establishing fragmentation patterns. It is concluded that these follow a characteristic path, which is common to all the ozonides studied and permits mass spectrometric identification.

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Mass Spectra of β-Keto Esters

Canadian Journal of Chemistry ◽

10.1139/v72-433 ◽

1972 ◽

Vol 50 (16) ◽

pp. 2707-2710 ◽

Cited By ~ 2

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.

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