Novel β-lactam condensed 3-thiaquinolines: an efficient synthesis and structural characterization

Quinoline analog 2-aryl-4H-3,1-benzothiazine derivatives 8–13, obtained by the condensation of o-aminobenzyl chloride 1 with substituted thiobenzamides 2–7, were transformed to azeto[2,1-a][3,1]benzothiazin-1-one derivatives 18–23a,b,c and 24d,e by reaction with the corresponding substituted acetyl chlorides 14–17 in the presence of triethylamine. The structures of the new molecules were determined by NMR spectroscopy and electron ionization (EI) mass spectrometry. The typical EI+ mass spectrometric fragmentations of 8–13 and 18–23a,b,c and 24d,e are discussed in detail.