Ruthenium Catalyzed Regioselective β‐C( sp 3 )−H Functionalization of N ‐Alkyl‐ N′ ‐ p– nitrophenyl Substituted Piperazines using Aldehydes as Alkylating Agents

Herein, we disclose a ruthenium-catalyzed regioselective beta-C(sp(3))-H bond functionalization on the piperazine core using aldehydes as alkylating agents. The present transformation appears to go through the dehydrogenation of the piperazine to propagate to enamine in situ, followed by nucleophilic addition to the aldehyde and hydrogenation to result in the regioselective beta-C(sp(3))-H alkylation. A variety of aromatic, heteroaromatic, aliphatic aldehydes were employed for the C-3 alkylation of N-alkyl-N '-p-nitrophenyl substituted piperazines.