A tandem double Friedel-Crafts reaction of indoles and nonsymmetrical divinyl ketones has been achieved. The tandem reaction forms complex [6-5-7]-tricyclic Indoles in excellent yields. The reaction is completely regioselective and offers high levels of syn diastereoselectivity. The reaction Is also seen to be sensitive to substrate structure and catalyst.
Silvanus, A. C., Heffernan, S. J., Liptrot, D. J., Kociok-Kohn, G., Andrews, B. I., & Carbery, D. R. (2009). Stereoselective double Friedel-Crafts alkylation of indoles with divinyl ketones. Organic Letters, 11(5), 1175-1178. https://doi.org/10.1021/ol900014a