Results Reagent DBP is a high-melting, stable crystalline compound that has been prepared previously by the reaction of sulfur monochloride with potassium phthalimide in a petroleum ether suspension! In our hands, this procedure gave erratic results. However, DBP (2) was readily available by the reaction of sulfur monochloride on dry, recrystallized phthalimide in tetrahydrofuran in the presence of triethylamine. The related succinimide reagent 3 was ...