Recyclable Copper-Catalyzed Cascade Coupling/Condensation/ Deacylation Reaction of 2′-Halotrifluoroacetanilides with β-Keto Esters toward 2-(Trifluoromethyl)indoles

An efficient heterogeneous copper-catalyzed cascade coupling/condensation/deacylation reaction of 2 '-halotrifluoroacetanilides with beta-keto esters has been developed. The reaction proceeds smoothly in anhydrous dimethyl sulfoxide at 80-90 degrees C using Cs2CO3 as base and 10-20 mol% SBA-15-immobilized l-proline-CuI complex [SBA-15-l-Proline-CuI] as catalyst and provides a general and practical method for the assembly of a variety of polysubstituted 2-(trifluoromethyl)indoles in good to high yields. This heterogenized copper catalyst can be easily recovered via a simple centrifugation process and reused more than seven cycles with almost consistent catalytic activity.