Tandem Mass Spectrometric Study of Protonated and Lithiated Benzoxazepine Derivatives

Abstract

This thesis investigated the tandem mass spectrometric behavior of a series of protonated and lithiated benzoxazepine derivatives, with particular focus on the compound C₁₆H₁₅NO₄S, which served as the representative model for detailed structural interpretation. Initial MS screening demonstrated that sodium adducts generated only minimal product ions. In contrast, lithiated and protonated ions produced rich, well-defined fragmentation pathways. For the lithiated ions, the fragmentation was driven by strong Li⁺ coordination to carbonyl and sulfonyl oxygens, which promoted predictable α-cleavages and high-diagnostic fragment ions. These fragmentation trends were found to be consistent across all derivatives in the study, confirming that the adduction is the most effective strategy for structural elucidation of this molecular class. The experimental results establish reliable fragmentation rules for benzoxazepine derivatives and highlight the analytical advantage of Li⁺ attachment in MS/MS investigations. Overall, the findings contribute to a deeper understanding of the gas-phase behavior of heterocyclic sulfonyl compounds and provide a solid foundation for future studies involving bioactive benzoxazepine analogues.