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Cobalt-catalyzed synthesis of N-containing heterocycles via cyclization of ortho-substituted anilines with CO₂/H₂
- Ke, Zhengang, Yu, Bo, Wang, Huan, Xiang, Junfeng, Han, Juanjuan, Wu, Yunyan, Liu, Zhenghui, Yang, Peng, Liu, Zhimin
- Green chemistry 2019 v.21 no.7 pp. 1695-1701
- carbon dioxide, cobalt, green chemistry, hydrogen, hydrogen bonding, moieties
- The CO₂-involved synthesis of chemicals is of great significance from the green and sustainable chemistry viewpoint. Herein, we report a non-noble metal catalytic system composed of CoF₂, CsF and P(CH₂CH₂PPh₂)₃ (denoted as PP₃) for the synthesis of N-containing heterocycles from ortho-substituted anilines and CO₂/H₂. Mechanism investigation indicates that [Co(PP₃)H(CO₂)]⁺ is a catalytically active intermediate under working conditions; and CsF plays important roles in activating ortho-substituted anilines via hydrogen bond interactions, thus promoting the formation of the final products. This catalytic system is highly efficient, and allows a wide scope of ortho-substituted anilines, together with excellent functional group tolerance, affording various N-containing heterocycles in good to excellent yields.