Structural Expansion of Dibenzo[b,d]thiophene Sulfone through Functionalization at Bay Positions

We report a synthesis of 1,9-dibromodibenzo[b,d]thiophene sulfone, which was converted to a respective dilithio intermediate. Subsequent trapping with electrophiles afforded either 1-substituted (R = CHO, B(OH)2) or 1,9-disubstituted (R = CO2H, I) derivatives, indicating an effect of steric factors on the outcome of this reaction. Various annulation reactions were also probed giving rise to extended π-conjugated systems. The electronic and optical properties of all compounds were characterized by cyclic voltammetry, UV–vis spectroscopy, and DFT calculations.