A highly active and easily recoverable chitosan@copper catalyst for the C–S coupling and its application in the synthesis of zolimidine†
Aryl sulfones were synthesized using a highly active and easily recoverable heterogeneous Cu catalyst which was prepared by simply stirring an aqueous suspension of chitosan in water with copper salts. The chitosan@copper catalyst catalyzed the coupling reactions of aryl halides with sodium sulfinates to readily give the corresponding sulfones in good to excellent yields. The highly active catalyst can be reused many times without losing its catalytic activity. In addition, by using this protocol, the marketed drug zolimidine (antiulcer) could be synthesized easily.