NHC-Pd(II)-Im complex 1 was found to be an effective catalyst for the α-arylation of unprotected oxindoles with aryl chlorides to give products 4 in 44–98% yields under a N2 atmosphere. Furthermore, if the reactions were first performed under conditions identical to those for the α-arylation reaction for 12 h and then exposed to air for another 3 h, 3-aryl-3-hydroxy-2-oxindoles 5 can be obtained in 49–84% yields in a one-pot procedure.
