A "green" route to perylene dyes:: Direct coupling reactions of 1,8-naphthalimide and related compounds under mild conditions using a "new" base complex reagent, t-BuOK/DBN

The direct coupling reactions of 1,8-naphthalimide compbounds efficiently occurred at 130 or 170 degreesC without the intervention of the leuco form dyes in the presence of bast! complex reagent, t-BuOK/1,5-diazabicyclo[4.3.0]non-5-ene (DBN), to give the corresponding perylene dyes in good yields with >95% purities. A possible mechanistic speculation for these oxidative coupling reactions is briefly discussed.