Sporidesmins. Part X. Synthesis of polysulphides by reaction of dihydrogen disulphide with disulphides and thiols

The structure of sporidesmin E suggests that it is biosynthesised from sporidesmin by a sulphurising enzyme analogous to a peroxidase. Accordingly, the reaction of dihydrogen disulphide with sporidesmin, dehydrogliotoxin, and other disulphides, has been studied. Polysulphides were obtained in all cases, but the reaction of dibenzyl disulphide with dihydrogen disulphide was slow. By contrast phenylmethanethiol reacted smoothly with the reagent to give di-, tri-, tetra-, and penta-sulphides, and this oxidation appears to be general. The epitrithiadioxopiperazines were light-sensitive and were converted photolytically into equimolecular mixtures of di-, and tetra-sulphides. By use of 35S-labelled polysulphides it was shown that the photolysed sulphur was that inserted by the dihydrogen disulphide.