93250-27-2Relevant articles and documents
The role of hydrogen migration in the mechanism of alcohol elimination from MH+ ions of ethers upon chemical ionization
Morlender-Vais,Mandelbaum
, p. 1124 - 1132 (2007/10/03)
An enhanced elimination of alcohol under isobutane CI conditions, resulting in highly abundant [MH - ROH]+ ions, has been observed in several primary and secondary ethers having a tertiary β-position (methine), as compared with those with β-methylene. This elimination exhibits a significant degree of stereospecificity in stereoisomeric 2-methyl-1-methoxycyclohexanes 4 and 1-methoxy-trans-decalins 7, affording more abundant [MH - ROH]+ ions in the cis isomers 4c and 7tc than in their trans counterparts 4t and 7tt. These findings suggest involvement of a 1,2-hydride migration from the β- to α-position in the course of the alcohol elimination from the MH+ ions of the above cis-ethers, resulting in tertiary carbocation structures. The proposed mechanism of alcohol elimination is supported by a considerable deuterium isotope effect detected in β-deuterium-labeled cis-2-methyl-1-methoxycyclohexane and by a CID study of the structures of [MH - ROH]+ ions obtained from cis- and trans-1,2-dialkoxycyclohexanes. Ring contraction by a Meerwein-type rearrangement has also been observed in the latter system.
