Gold(I)-Catalyzed Synthesis of 2,2'-Biindoles via One-Pot Double Cycloisomerization Strategy.

The first systematic, concise and target-directed gold(I)-catalyzed synthesis of a family of 2,2'-biindoles containing different substitution patterns is described. The developed protocol involves the synthesis of 1,3-diyne-anilines followed by a one-pot gold(I)-catalyzed double cycloisomerization, giving rise to an efficient, broad and general protocol to get different 2,2'-biindoles under mild reaction conditions. Due to the methodological restriction of present methods for accessing this class of compounds, herein we present our synthetic proposal which allowed the preparation of several examples of 2,2'-biindoles. Their functionalization-guided us to the discovery that the chemical stability, is substitution structure-dependent.