Mass spectrometry of sterols. Electron ionization induced fragmentation of C-4-alkylated cholesterols.
The electron impact ionization of C-4-alkylated cholest-5-en-3beta-hydroxysterols has been investigated. The mass spectra of the C-4-alkylated cholesterols contain a number of ions in the high mass region for which analogous ions are not found in the spectrum of cholesterol. Detailed studies of the composition and origin of these ions have been made by high resolution mass spectrometry and analysis of metastable ions. In addition, a large number of isotopically (deuterium and 18O) substituted C-4-alkylated analogues have been prepared to assist in the interpretation of the spectra. The combined results indicate the occurrence of a number of very complex and unusual electron ionization induced fragmentations. Most notable of the findings reported herein concerns the demonstration of the formation of an ion involving loss of the elements of ring A with an intramolecular shift of the oxygen and hydrogen atoms of the hydroxyl function to the charge-retaining species.
Sterol synthesis. A simplified method for the synthesis of 32-oxygenated derivatives of 24,25-dihydrolanosterol.
A simplified method is described for the preparation of 14 alpha-hydroxymethyl-4,4-dimethyl-5 alpha-cholest-8-en-e beta-ol, 14 alpha-hydroxymethyl-4,4-dimethyl-5 alpha-cholest-7-en-3 beta-ol, and 14 alpha-hydroxymethyl-4,4-dimethyl-5-alpha-cholest-6-en-3 beta-ol from commercial lanosterol. This method represents a modification of the approach introduced by Fried and co-workers (Fried, J., J. W. Brown, and L. Borkenhagen. 1965. Tetrahedron Lett. 2499-2504).
Tabellen zur massenspektrometrischen strukturaufklärung von steroiden—IV : Schlüsselbruchstücke und schlüsseldifferenzen von steroidderivaten
Zusammenfassung In dieser Arbeit werden Schlusselbruchstucke und Schlusseldifferenzen wichtiger, stickstofffreier Steroidderivate abgehandelt. Die Tabellen sind analog denen von Teil 2 und 3 aufgebaut.