Regiodivergent Control in the Gold(I) Catalyzed Synthesis of 7‐Pyrazolylindoles from 1‐Propargyl‐1H‐benzotriazoles and Ynamides through α‐Imino Gold(I) Carbene Complexes

A smooth, gold catalyzed, atom‐economical and regioselective synthesis of indoles is reported here. The reaction occurs from a nucleophilic attack of in situ synthesized triazapentalenes to gold activated ynamides and involves the participation of α‐imino gold carbene complexes. The use of sulfonyl ynamides drives the reaction to the formation of 2‐amidosubstituted indoles. However, the employment of 2‐oxazolidinolylynamides allows the formation of both isomers, such as, 2‐amido‐ and 3‐amidosubstituted indoles. In this case, the regioselection could be controlled by a correct choice of the catalyst ligand and the electron‐donating capability of the aryl substituent of the ynamide. A correct control in both parameters permits a totally regioselective synthesis of one or the other regioisomer. Isolation of key intermediates and X‐ray analysis allowed for a plausible explanation for this behavior.