Gold(i)-catalyzed pathway-switchable tandem cycloisomerizations to indolizino[8,7-b]indole and indolo[2,3-a]quinolizine derivatives.

Experimental and theoretical explorations were performed on the pathways of the cascade cycloisomerizations of tryptamine-N-ethynylpropiolamide substrates. The methodology provided a common strategy to access either indolizino[8,7-b]indoles or indolo[2,3-a]-quinolizines in a switchable fashion.