29944-53-4Relevant academic research and scientific papers
Desorption Chemical Ionization Mass Spectrometry of Epimeric 3-Hydroxysteroids and Derivatives. Stereoselectivity and Nucleophilic Substitution with Ammonia
Tecon, Pierre,Hirano, Yutaka,Djerassi, Carl
, p. 277 - 285 (2007/10/02)
The desorption chemical ionization mass spectra, using ammonia as reagent gas, of several epimeric 3-hydroxysteroids and their ether and carboxylic acid ester derivatives are reported.In the case of steroids possessing a Δ4- or Δ5-3α-benzoate moiety, stereospecific stabilization of the protonated molecular ion + is observed.This behaviour is rationalized in terms of interaction of the double bond and the protonated benzoate group at C-3.Nucleophilic substitution by NH3 is observed when a double bond is present in the vicinity of the substitution center.The nature and the stereochemistry of the leaving group influence this substitution reaction.Our results seem to indicate the operation of a two-step mechanism (e.g.SN1 type reaction) rather than a SN2 type mechanism for the formation of the substitution ion +.
