Rhodium(III)-catalyzed intramolecular redox-neutral annulation of tethered alkynes: formal total synthesis of (±)-goniomitine.

A Rh(III)-catalyzed intramolecular redox-neutral atom-economic annulation of a tethered alkyne has been developed to efficiently construct 2-amidealkyl indoles with completely reversed regioselectivity by a C-H activation pathway. Furthermore, using the Rh(III)-catalyzed C-H activation/annulation as a key step, a one-pot synthesis of pyrido[1,2-a]indoles has also been developed and applied to a highly efficient formal total synthesis of (±)-goniomitine.