Ag(I)-Catalyzed Domino Cyclization–Addition Sequence with Simultaneous Carbonyl and Alkyne Activation as a Route to 2,2′-Disubstituted Bisindolylarylmethanes

An efficient synthesis of symmetrical 3, 3′-bisindolylarylmethanes with various substituents on the indole moiety has been developed by Ag(I)-catalyzed cycloisomerization and an deoxygenative addition sequence on o-alkynylanilines and aryl aldehydes. Ag(I) is proposed to activate alkyne unit and carbonyl moiety simultaneously leading to a domino first 5-endo-dig indole annulation, addition to C═O, second indole annulation, and its dehydroxylative addition.