Ruthenium catalyzed β-C(sp3)-H functionalization on the 'privileged' piperazine nucleus.

β-C(sp3)-H functionalization on the 'privileged' piperazine nucleus has been disclosed using ruthenium catalysis. The ruthenium catalyzed synthesis of a variety of piperazine fused indoles from ortho-piperazinyl (hetero)aryl aldehydes is presented. This transformation takes place via the dehydrogenation of piperazine followed by an intramolecular nucleophilic addition of the transient enamine moiety onto the carbonyl group and aromatization cascade.