The insertion and extrusion of heterosulfur bridges. X. Conversions in the triphenylene‐triphenylo[4,5‐bcd] thiophene system

Sulfur bridging of triphenylene (3) to form triphenylo[4,5‐bcd]thiophene (4) is effected in 18% yield by means of hydrogen sulfide and a molybdena catalyst (CMA‐1) at 500°. Compound 4 is purified through its sulfoxide, converted into its sulfone (6), and desulfurized (by means of CMA‐1 plus methanol‐benzene) back to 3. The ultraviolet absorption spectrum of 4 resembles closely that of benzo[e]pyrene. On electron impact 4 shows little skeletal fragmentation, while 6 readily evolves sulfur monoxide and the formyl group.