title: Atmospheric pressure chemical ionization multi-stage mass spectrometry in the characterization of stereoisomeric synthons of cyclopropane amino acids.
abstract: The mass spectrometric behaviour of (1S,2R)-, (1R,2R)-, (1R,2S)- and (1S,2S)-2-[(S)-2,2-dimethyl-1, 3-dioxolan-4-yl]-1-spiro-¿4'[2'-phenyl-5'(4'H)-oxazolone]¿ cyclopropane (2) and (1S,2R)-, (1R,2R)-, (1R,2S)- and (1S, 2S)-methyl-1-benzamido-2-[(S)-2,2-dimethyl-1, 3-dioxolan-4-yl]cyclopropanecarboxylate (3) was studied under atmospheric pressure ionization conditions and by multi-stage mass spectrometric (MS(n)) experiments performed with an ion trap. Interestingly, by using methanol as solvent, compounds 2 lead to [M + H + CH(3)OH](+) ions which, as proved by collisional experiments, exhibit the same structure of the corresponding compound 3. MS/MS of [MH](+) ions allows a clear characterization of the different stereoisomers, which give rise to specific fragmentation pathways, rationalized with respect to the structure of the neutral molecules.
authors.affiliation: CNR, Area della Ricerca, Corso Stati Uniti 4, I-35100 Padova, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Cristoni
authors.forename: C
authors.initials: C
authors.lastname: Cativiela
authors.forename: A I
authors.initials: AI
authors.lastname: Jiménez
authors.forename: P
authors.initials: P
authors.lastname: Traldi
mesh_terms: D000399:Air Pressure; D000596:Amino Acids / Q000138:chemical synthesis*; D003521:Cyclopropanes / Q000138:chemical synthesis*; D013058:Mass Spectrometry; D013237:Stereoisomerism
chemical_list: D000596:Amino Acids; D003521:Cyclopropanes