Unimolecular depurination of protonated deoxyribonucleosides in the gas phase: A fast atom bombardment tandem mass spectrometric investigation

The spontaneous or collision‐induced unimolecular dissociations of base‐protonated 2′‐deoxyribonucleosides afford, in the gas phase and in the absence of solvent, high yields of protonated nucleobases. The release of neutral bases corresponds to a high‐energy reaction path and does not compete with the formation of the protonated bases. A determinant solvent effect has to be invoked to explain the opposite behaviour, which is exhibited by the same precursors, dissociating unimolecularly, in aqueous acidic solution.