Synthesis of 2-Aminoindoles through Gold-Catalyzed C-H Annulations of Sulfilimines with N-Arylynamides.

A new gold-catalyzed C-H annulation of sulfilimines with N-phenylynamides is presented. As key intermediates of this operationally simple reaction, the in situ generated α-imino gold carbenes insert into the ortho C-H bonds of the phenyl groups to afford 2-aminoindoles bearing a variety of substitution patterns in high selectivities. This reaction offers a facile approach to biologically important 2-aminoindoles by using inexpensive and readily available starting materials.