Methoxymethyl Cations. 2. Reactions with Allylic Ethers and Sulfides in the Gas Phase

Article abstract of DOI:10.1021/jo00334a026

Reactions of allylic compounds 3-methoxy-1-propene and 3-(methylthio)-1-propene with gaseous methoxymethyl cations generated from methyl ethers on electron impact have been investigated by ion cyclotron resonance techniques.Three modes of reaction have been identified for the allylic sulfide with CH3OCH2⁺ that correspond to the elimination of the elements of CH2=O, CH3OH, and CH3SH.The allylic ether and CH3OCH2⁺ reacted to eliminate CH3OH predominantly.Pathways for these reactions were studied by using isotopic labels.The results are interpreted in terms of attack of the reactant ion at the terminal carbon of the allyl group followed by hydride and/or proton transfers and elimination of CH2O, CH3OH, or CH3SH.Oxygen lost as the neutral arose predominantly but not exclusively by cleavage of the methylene-oxygen bond of the reactant ion.Methylthiolation of 3-(methylthio)-1-propene also was achieved by reaction with CH3OCH2⁺ in the presence of methyl disulfide.The score of a small amount of label scrambling in deuterium-labeled reactant ions is discussed.