Organic chemistry of gas-phase ions. Part 1. Effect of the protonation site in stereoisomeric norbornenols

Abstract

Chemical ionization (c.i.) mass spectrometry has been used to study stereochemical effects in the isomeric norbornenols (1)–(5). Protonation and subsequent water abstraction ractions can be used to probe the stereochemistry of these alkenols. The nature of the protonation sites, and the possibilities of interaction between them or of proton transfer, seem to play a very important role in determining the relative stabilities of the ions MH⁺ and (MH – H₂O)⁺. The interpretation of the results is supported by MNDO quantum chemical calculations executed on the protonation sites of the norbornen-7-ols (4). The evidence for gas-phase anchimeric assistance in the water-abstraction reactions of some norbornenols is discussed.