Synthesis of 3-Iodoindoles by the Pd/Cu-Catalyzed Coupling of N,N-Dialkyl-2-iodoanilines and Terminal Acetylenes, Followed by Electrophilic Cyclization
Dawei Yue, Tuanli Yao and Richard C. Larock*
*Department of Chemistry, Iowa State University, Ames, Iowa 50011, Email: larockiastate.edu
D. Yue, T. Yao, R. C. Larock, J. Org. Chem., 2006, 71, 62-69.
Various 3-iodoindoles have been prepared in excellent yields by a Sonogashira coupling of terminal acetylenes with N,N-dialkyl-o-iodoanilines, followed by an electrophilic cyclization of the resulting N,N-dialkyl-o-(1-alkynyl)anilines using I2 in CH2Cl2. The reactivity of the carbon-nitrogen bond cleavage during cyclization follows: Me > n-Bu, Me > Ph, and cyclohexyl > Me.
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