Benzene-fused heterocycles containing tellurium, selenium and sulphur

21 BENZENE-FUSED HETEROCYCLES CONTAINING TELLURIUM, SELENIUM AND SULPHUR 

The reaction of the stannoles Aa and Ab with TeCl4 affords the substitution of the dimethyltin moiety by the dichlorotelluro group to give the thio- and selenodichloro telluroles Ba and Bb. The spiro tellurole C is obtained by treatment of Aa, respectively, with 0.5 equiv. of 

When Ba is treated with aqueous THF at reflux, a mixture of C and tetrathiocins D and E is formed in ratios that depend from the heating time. 

Even more Bb, submitted to the same treatment, yields a mixtnre of F and G, tetra-chalcogenines containing both sulphur and seleninm in the eight-membered ring.  

The title compounds A and B are synthesized in accordance with the following scheme  

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