Ynamides react with conjugated enynes in intramolecular [4+ 2] cycloadditions to afford substituted indolines that undergo oxidation with o-chloranil to furnish the corresponding indoles. The cycloaddition substrates are easily assembled from derivatives of 3- butynylamine by Sonogashira coupling with alkenyl halides followed by copper-catalyzed N- alkynylation with acetylenic bromides. Diynamides participate as particularly reactive 2π ...
