abstract |
A process for preparing a benzo fused heterocyclic sulfonyl halide comprising reacting a benzo fused heterocyclic compound with an SO3 complex in the presence of a water immiscible, non-reactive solvent, at a temperature of from about 0 DEG C. to about 75 DEG C., cooling, if necessary, to a temperature of from about -25 DEG C. to about 65 DEG C. and then adding oxalyl halide. |