Sulfonamide-directed gold-catalyzed [2+2+2]-cycloadditions of nitriles with two discrete ynamides to construct 2,4-diaminopyridine cores

Gold-catalyzed [2+2+2]-cycloadditions of two discrete ynamides and one nitrile afford 2,4-diaminopyridine derivatives that are not readily prepared from typical low-valent-metal catalysts. Our mechanistic analysis reveals that the reaction chemoselectivity is controlled by the types of sulfonamides of ynamides.