Study on Tin Powder-Promoted Allylation of 3-Aryl-3-hydroxy-2-oxindoles

An efficient tin-powder-promoted C-C coupling reaction of 3-aryl-3-hydroxy-2-oxindoles with allyl bromide was disclosed, which makes tin-powder-promoted reactions beyond 1,2-addition to C=O or C=N double bounds, and provides a convenient and facile protocol for the synthesis of potentially bioactive 3,3'-disubstituted-2-oxindoles in good to excellent yields. The method is highly efficient and environmentally benign with low cost and concise manipulation.