Decomposition of Protonated Threonine, Its Stereoisomers, and Its Homologues in the Gas Phase:  Evidence for Internal Backside Displacement

Abstract

Protonated threonine and its allo diastereomer exhibit different proportions of collisionally activated dissociation (CAD) product ions. N-Methylation attenuates these differences. Water loss from protonated allo-threonine gives protonated trans-3-methylaziridinecarboxylic acid via an internal S(N)2 pathway, rather than protonated vinylglycine.