Highly substituted indole library synthesis by palladium-catalyzed coupling reactions in solution and on a solid support.

3-Iodoindoles have been synthesized by the iodocyclization of N,N-dialkyl-o-(1-alkynyl)anilines, obtained by the Pd/Cu catalyzed coupling of terminal acetylenes with N,N-dialkyl-o-iodoanilines. These 3-iodoindoles undergo palladium-catalyzed Sonogashira and Suzuki coupling reactions to yield 1,2,3-trisubstituted indoles. These reactions have been applied to parallel library synthesis utilizing commercially available terminal acetylenes and boronic acids. The aforementioned chemistry has also been carried out on a chlorinated Wang resin as a solid support, affording 1,2,3,5-tetrasubstituted indoles after cleavage from the support. A diverse 42-member library of highly substituted indoles has been synthesized.