Stereochemical effects in the EI mass spectra of cis- and trans-fused octa/hexahydro-3,l-benzoxazines and -benzothiazines

Abstract

The electron ionization mass spectra of cis- and trans-fused 2-oxo- (1,2), and 2-thioxo-4-phenyloctahydro-2H-3,l-benzoxazines (3,4), 2,4-diphenylhexahydro- 3,1-benzoxazines (5,6) and 2-phenylimino-4-phenylhexahydro-3,l-benzoxazines (7,8) and -benzothiazines (9,10) were recorded, and the fragmentation pathways established and compared to their 4-unsubstituted counterparts. Effects of stereochemistry, substitution, and (in the case of 2-phenylimino derivatives) of an intramolecular cyclization of the [M-H]+ ions were observed in the mass spectra. In general, mass spectral behavior was similar for the isomeric compounds although they could usually be differentiated from each other based on the relative abundances of their characteristic fragment ions. © ARKAT.