Facile synthesis of pyrroloindoles via a rhodium(ii)-catalyzed annulation of 3-benzylidene-indolin-2-ones and α-imino carbenes.

The annulation of 3-benzylidene-indolin-2-ones with α-imino rhodium carbenes generated in situ from N-sulfonyl-1,2,3-triazoles is presented. Through the appropriate choice of catalyst, the reactions can be reasonably modulated, and consequently, a number of pyrroloindole derivatives were constructed in moderate to excellent yields.