A new approach for the construction of indoles employing the air-and moisture-stable reagent Cp2TiCl2 is described. The key steps involved are (1) the intermolecular insertion reactions of an olefin and a titanocene-stabilized benzyne complex and (2) the Pd-catalyzed aryl amination reaction. The simplicity and availability of the requisite starting materials give the method a broad scope for the preparation of polysubstituted indoles.
“Titanocene-based method for indole synthesis”, J. Am. Chem. Soc., 1998, 120(13), 3068-3073.