Efficient construction of indole rings from 2-ethynylaniline derivatives catalyzed by copper(II) salts and its application to the tandem cyclization reactions

The efficient cyclization reactions of the N-methanesulfonyl or N-ethoxycarbonyl derivatives of 2-ethynylanilines. functionalized on the benzene ring and/or the acetylene terminal into indoles catalyzed by either Cu(OTf)(2) or Cu(OAc)(2) are accomplished. The application of this reaction to the tandem cyclization reaction is also described. (C) 2002 Elsevier Science Ltd. All rights reserved.