2009 年 67 巻 7 号 p. 714-723
The three main parts; i.e., the preparations, structures and reactions of the 1-benzotelluropyrylium salts are described. The synthetic workup has been achieved by transformation from the tellurochromones, which were simply prepared by the reaction of the o-bromophenyl ethynyl ketones with sodium hydrogen telluride (NaHTe). The synthetic method for the preparation of the tellurochromones is based on the intramolecular ring closure of a tellurol moiety into a triple bond. The study shows that these salts, although being stable compounds, are highly reactive with various nucleophiles including OMe-, diethylamine, CN-, an active methylene compound and Grignard reagents, and also hydrogenation and hydrolysis to afford the successful corresponding 2- or 4-substituted tellurochromene derivatives. The chemistry of the 1-benzoselenopyrylium salts is also described. The thermolysis of the 2-azidoselenochromenes, which were easily obtained by the reaction of the selenopyrylium salts with sodium azide, resulted in a ring expansion to produce the novel stable 1,3-benzoselenazepines. X-ray structural analyses of the tert-butyltelluro- and selenopyrylium salts are also reported.