Synthesis of benzo fused heterocyclic sulfonyl chlorides

摘要

A process for preparing a benzo fused heterocyclic sulfonyl halide comprising reacting a benzo fused heterocyclic compound with an SO. sub.3 complex in the presence of a water immiscible, non-reactive solvent, at a temperature of from about 0 C. to about 75 C., cooling, if necessary, to a temperature of from about -25 C. to about 65. degree. C. and then adding oxalyl halide.