Ion–molecule reaction in the gas phase 3—nucleophilic substitution of 17ξ‐R‐5α,14β‐androstane‐14,17ξ‐diols under [NH4]+ chemical ionization conditions1
- 1 August 1984
- journal article
- research article
- Published by Wiley in Journal of Mass Spectrometry
- Vol. 19 (8) , 363-369
- https://doi.org/10.1002/oms.1210190803
Abstract
Under Ammonia chemical Ionization conditions the source decompositions of [M + NH4]+ ions formed from epimeric tertiary steroid alchols 14 OHβ, 17OHα or 17 OHβ substituted at position 17 have been studied. They give rise to formation of [M + NH4H2O]+ dentoed as [MHsH]+, [MsHH2O]+, [MsHNH3]+ and [MsHNH3H2O]+ ions. Stereochemical effects are observed in the ratios [MsHH2O]+/[MsHNH3]+. These effects are significant among metastable ions. In particular, only the [MsH]+ ions produced from trans‐diol isomers lose a water molecule. The favoured loss of water can be accounted for by an SN2 mechanism in which the insertion of NH3 gives [MsH]+ with Walden inversion occurring during the ion‐molecule reaction between [M + NH4]+ + NH3. The SN1 and SNi pathways have been rejected.Keywords
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