Nickel‐Catalyzed Synthesis of Structurally Diverse N‐(hetero)aryl Pyrroles

We report a simple protocol for the preparation of functionalized pyrroles employing 2,5-hexandione or succinaldehyde and anilines as starting materials in the presence of a well-defined homogeneous nickel catalyst (NiCl₂·6H₂O + dppe).

Abstract

Pyrrole is an important five-membered aromatic nitrogen compound found in various pharmaceuticals and natural products, including functional materials. Many methods have been developed to create substituted pyrroles. Nevertheless, the structurally diverse synthesis of N-substituted pyrroles is less documented. Herein, we describe a simple procedure for the preparation of functionalized pyrroles employing 2,5-hexandione and anilines as starting materials in the presence of a well-defined homogeneous nickel catalyst (NiCl₂·6H₂O + dppe). Sensitive functional groups in anilines, such as halogen (F, Cl, Br, and I), ester, nitrile, and sulfur moieties, were well-tolerated and yielded a diverse array of N-(hetero)aryl pyrroles in high yields (50%–95%). These results were relatively challenging to achieve with previous methods. The reaction also occurs efficiently with succinaldehyde to yield a series of desired N-aryl pyrrole skeletons.

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