GAS-PHASE SUBSTITUTION-REACTIONS BY RADICAL CATIONS .1. REACTION OF THE C-C RING-OPENED OXIRANE RADICAL CATION WITH PYRIDINE

Under conditions of chemical ionization the CC ring-opened oxirane radical cation transfers a methylene group to pyridine. This reaction leads to the formation of the 1-methylene-pyridinium radical cation with a high reaction selectivity. Experimental proof for this ion arises from: collisionally induced dissociation (CID) spectroscopy of the reaction product ions of the reaction of either pyridine, pyridine-d5, pyridine-15N with oxirane; CID spectroscopy of this reaction product compared with the 2-, 3-, 4-methyl pyridine radical cations. Further evidence for this ion and the reaction selectivity of its formation is obtained from MNDO calculations of the minimal energy requirement paths for the formation of the 3-methyl pyridine radical cation versus the 1-methylene-pyridinium radical cation. © 1990.