| Abstract: | Mass spectra of various functionalized lanostanes and their deuterated analogs are compared. It is proposed that the transfer of a hydrogen from the 18-methyl group to the 11-oxo group via a McLafferty rearrangement is made geometrically possible by prior ionization of the 13,14 bond which allows an optimum interatomic distance between the oxygen and hydrogen to be acquired; the 8,9 double bond is a requisite for electronic induction of this specific process. Transfer of the hydrogen from the 7β-hydroxy group to position 14 is implicated in the mass spectrum of 3β-acetoxy-7β-hydroxy-5α-lanostan-11-one. |
