Fragmentation of 2,1-benzisothiazoline 2,2-dioxides (benzosultams).

The most important process involving benzosultams is an extrusion of sulfur dioxide leading to aza-ortho-xylylenes. We investigated mass spectra of benzosultams and have found that, usually, a loss of SO2 from molecular ion resulting in the formation of [M-64] ion is a predominant process.
We proposed two mechanisms of elimination of SO2 from molecular ions of benzosultams:
a) concerted mechanism with simultaneous break of sulfur-nitrogen and carbon-sulfur bonds resulting in direct formation of azaxylylene, and
b) stepwise mechanism in which the carbon-sulfur bond is broken first, and [1,5] hydrogen shift precedes elimination of SO2

Fragmentation of cycloalkane-spiro-benzosultams

The molecular ion of cyclopropanespiro-benzo-sultam shows much more complex fragmentation pattern, formation of [M-64] ion proceeds to a minor extent.
In 4-nitro-3-cyclopropanespirobenzosultam the initial fragmentation involves interaction of methylene and nitro groups and results in elimination of formaldehyde

. In cyclobutanespirobenzosultam the [2+2] cycloreversion resulting in elimination of ethylene precedes the elimination of SO2.

W. Danikiewicz, K. Wojciechowski, S. Kosiński, and M. Olejnik  J. Mass Spectrom. 2001, 36, 430.

Fragmentation of N-(methoxymethyl)benzosultams.

In N-(methoxymethyl)-benzosultams  a novel rearrangement resulting in an elimination of formaldehyde was observed. For this process we proposed a mechanism involving a presence of an ion-neutral complex.

W. Danikiewicz and K. Wojciechowski Rapid. Commun. Mass Spectrom. 1996, 10, 36.

Fragmentation of 7-nitrobenzosultams.

In 1-alkyl-7-nitrobenzosultams primary fragmentations involve interaction of N-alkyl and nitro group resulting in an elimination of carbonyl compounds.

W. Danikiewicz and K. Wojciechowski Eur. Mass Spectrom. 1997, 3, 55.

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Last update 27.08.2008.