New Methodology of Heterocyclization: the Electrophilic Addition Reactions of Selenium Di- and Tetrahalides and Tellurium Tetrachloride to Diethynyl Silanes and Germanes

The syntheses and structures of new classes of unsaturated five-membered heterocycles containing selenium or tellurium and silicon or germanium in the rings prepared on the basis of new heterocyclization reactions of selenium dihalides and tetrahalides or tellurium tetrachloride with the bridged diacetylenes are described. The mechanism of the heterocyclization is discussed.