Gold-Catalyzed Divergent Ring-Closing Modes of Indole-Tethered Amino Allenynes

Indole-tethered amino allenynes were chemodivergently cyclized for the controlled preparation of fused polycyclic indoles using gold catalysis. Double cyclization of terminal allenynes afforded hexacyclic 15 H-indolo[1,2,3-de]quinolino[3,2,1-ij]quinoxalines, in which allenynes bearing a substituted alkyne at the terminal end generated 12,13-dihydro-7 H-indolo[3,2-c]acridines, which are 5-membered cyclized adducts. Density functional theory calculations were performed to shed light on this difference in reactivity.Financial support for this work by the MINECO and FEDER (Projects CTQ2016-81797-REDC, CTQ2015-65060-C2-1-P, CTQ2015-65060-C2-2-P, and CTQ2016-78205-P) is gratefully acknowledged. F.H. thanks UCM for a predoctoral contract. We thank Prof. J. M. Gonz#lez and Prof. A. Ballesteros (Universidad de Oviedo) for the kind donation of IPy2BF4Peer Reviewe