Nano n-propylsulfonated γ-Al2O3: a new, efficient and reusable catalyst for synthesis of spiro[indoline-3,4-pyrazolo[3,4-e][1,4]thiazepine]diones in aqueous media

Nano n -propylsulfonated γ-Al 2 O 3 is easily prepared by the reaction of nano γ-Al 2 O 3 with 1,3-propanesultone. This reagent can be used as an efficient catalyst for the synthesis of spiro [indoline-3,4-pyrazolo[3,4- e ][1,4]thiazepine]diones in aqueous media. This new method consistently has the advantages of excellent yields and short reaction times. Further, the catalyst can be reused and recovered several times. Copyright © 2013 John Wiley & Sons, Ltd.