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The mass spectra of some C‐19 modified 5α‐cholestane derivatives
Author(s) -
Shoppee C. W.,
Coll J. C.,
Lack Ruth E.
Publication year - 1970
Publication title -
organic mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0030-493X
DOI - 10.1002/oms.1210040140
Subject(s) - chemistry , substituent , mass spectrum , hydroxymethyl , acetic acid , cholestane , medicinal chemistry , hydrogen chloride , fragmentation (computing) , stereochemistry , organic chemistry , ion , computer science , operating system
The mass spectra of twenty‐seven C‐19 modified cholestane derivatives have been determined, and have been compared with the mass spectra of similar compounds reported 1 in the cholesteryl series. In the spectra of 2α,19‐dihydroxy‐5α‐cholestane (la), initial loss of the 10β‐hydroxymethyl group was observed followed by loss of water, whereas with the 2α‐methoxy and 2α‐acetoxy derivatives (Ib, Ic), loss of the 2α‐substituent as methanol and acetic acid respectively, preceded the elimination of the 10β‐hydroxymethyl group. Loss of the 10β‐hydroxymethyl group was also observed in Δ 1 ‐, Δ 2 ‐ and 2‐oxo derivatives (VI, Va and VII), whilst loss of both the 1 substituent and the 10β‐hydroxymethyl group from the molecular ion was observed with the 1α‐ol (IIa) and the 1β‐yl‐chloride (III). In a series of 19‐acetoxy derivatives loss of acetic acid [M – 60] from the 19‐acetoxy group, involving abstraction of a sterically favourable hydrogen, always occurred, although this was usually accompanied by loss of the 10β‐acetoxymethyl residue [M – 73]. The mass spectra of a series of 10β‐carboxylic acids and their methyl esters were more complex with three or more fragmentation patterns being observed. 1,3‐Diaxial interactions, similar to those observed in chemical reactions, were observed in the mass spectra of three 2β‐oxygenated‐19‐substituted compounds.