Generation of the First Tellurium-Containing Diheteropentalene

The known diester dibromomethylthiophene was converted to the tellurolo[3,4-c]thiphene, the first example of a diheteropentalene containing a tellurophene annelated across the 3,4-c position to thiophene. It is stable in solution and adds to DMAD across the 2,5-positions in tellurophene. The intermediate loses tellurium and collapses to a tetracarbomethoxy benzo[c]thiophene derivative.