Rhodium-catalyzed intramolecular cascade sequence for the formation of fused carbazole-annulated medium-sized rings by cleavage of C(sp2)–H/C(sp3)–H bonds

Abstract

The rhodium(III)-catalyzed intramolecular annulation of alkyne-tethered 3-(indol-3-yl)-3-oxopropanenitriles for the synthesis of fused carbazole scaffolds via C–H activation has been developed. A series of six-, seven-, and eight-membered hydroazepino[3,2,1-jk]carbazoles were achieved. This reaction proceeded under mild reaction conditions and with a broad substrate scope. The reaction involved sequential cleavage of C(sp²)–H/C(sp³)–H bonds and annulation with the tethered alkyne.