Mass spectral fragmentation patterns of 1a,3-diaryl-1,1,4,4-tetrachloro-1a,2,3,4-tetrahydro-1H-azirino[2,1-e]­[1,6]benzothiazocines

✍ Scribed by Jiaxi Xu; Ruoxi Lan; Sheng Jin

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 64 KB
• Volume: 13
• Category: Article
• ISSN: 0951-4198
• DOI: 10.1002/(sici)1097-0231(19990730)13:14<1511::aid-rcm677>3.0.co;2-5

✦ Synopsis

The mass spectrometric behaviour of three 1a,3-diaryl-1,1,4,4-tetrachloro-1a,2,3,4-tetrahydro-1H-azirino [2,1-e][1,6]benzothiazocines has been studied with the aid of mass-analyzed ion kinetic energy spectrometry and exact mass measurements under electron impact ionization. All compounds show a tendency to eliminate a neutral substituted/unsubstituted 1,1-dichlorostyrene from the eight-membered thiazocine ring to yield azirino[2,1-c][1,4]benzothiazine ions, which can then lose a chlorine radical and a sulfur atom to form azirino[2,1-c][1,4]benzothiazine ions and dihydroquinoline ions. All compounds could also eliminate a chlorine radical plus hydrogen chloride, stepwise or consecutively, to undergo a ring enlargement rearrangement to produce nine-membered 1,7-benzothiazonine ions. The [M À Cl] ions could undergo a four-membered ring rearrangement to yield 1,5-benzothiazepine ions by loss of 1,1dichlorostyrene or styrene ions and HCl, and undergo a , a-cleavage to form benzothiazine ions by loss of arylchlorocyclopropane. The [M À Cl À HCl] ions could further eliminate some atoms, small molecules or molecular fragments to form some abundant fragment ions.