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Diphenylnitrilimin (II), hergestellt aus de Sulfinen (III) zu den Addukten (IVa) oxidiert werden konnen.

Unambiguous Configurational assignment of syn and anti-isomers of methyl-substituted aromatic Sulphines has been achieved by means of: (a) intermolecular hydrogen bonding with weak acids; (b) intramolecular association in 2-hydroxy-(2′-methyl)thiobenzophenone S-oxide; (c) aromatic solvent induced shift measurements; and (d) carbon-13 n.m.r. spectra. The thermodynamic and kinetic parameters for the thermal interconversion of the isomers have also been determined. These values are discussed in terms of possible isomerisation mechanisms.

The cycloaddition reactions of aromatic sulphines, such as thiobenzophenone S-oxide and thiofluorenone S-oxide, with 2-diazopropane lead to 1,3,4-thiadiazoline 1-oxides in high yields. Diazomethane reacts more sluggishly with sulphines: only with thiofluorenone S-oxide was a cycloadduct obtained. The structure of the cycloadducts has been proven by photochemical extrustion of sulphur monoxide from 2,2-dimethyl-5,5-di-(p-tolyl)-1,3,4-thiadiazoline 1-oxide. In solution the cycloadducts readily undergo a retro-cycloaddition. The adduct from thioxanthen-9-thione SSS′-trioxide and 2-diazopropane not only reverts to the starting sulphine, but also shows a reversed retro-cycloaddition reaction to give diazothioxanthen SS-dioxide and thioacetone S-oxide.