Sulfur Transfer Versus Phenyl Ring Transfer in the Gas Phase: Sequential Loss of CH3OH and CH3O-P=O from Protonated Phosphorothioates.
J Am Soc Mass Spectrom
; 30(3): 459-467, 2019 Mar.
Article
em En
| MEDLINE
| ID: mdl-30569428
ABSTRACT
Collisional activation fragmentation of protonated phosphorothioates leads to skeletal rearrangement and formation of aryl sulfenylium cation (R-PhS+) via successive eliminations of CH3OH and CH3O-P=O. To better understand this unusual fragmentation reaction, isotope-labeling experiments and density functional theory (DFT) calculations were carried out to investigate two mechanistic pathways. In route 1, a direct intramolecular transfer of the R-phenyl group occurs from the oxygen atom to the sulfur atom on thiophosphoryl to form methoxyl S-(3-methyl-4-methylsulfanyl-phenyl) phosphonium thiolate (a4), which subsequently dissociates to form the m/z 169 cation. In route 2, the sulfur atom of the thiophosphoryl group undergoes two stepwise transfer (1,4-migration to the ortho-carbon atom of the phenyl ring followed by 1,2-migration to the ipso-carbon atom) to form an intermediate isomer, which undergoes the subsequent dissociation to form the m/z 169 cation. DFT calculations suggested that route 2 was more favorable than route 1 from the point view of kinetics. Graphical Abstract.
Texto completo:
1
Coleções:
01-internacional
Temas:
Agentes_cancerigenos
Base de dados:
MEDLINE
Idioma:
En
Revista:
J Am Soc Mass Spectrom
Ano de publicação:
2019
Tipo de documento:
Article