Palladium‐Catalyzed Tandem Cyclization Strategy for the Assembly of 3‐Halo‐1,2,5‐triarylpyrroles from N‐Alkylanilines and Haloalkynes

• Published in: Chinese journal of chemistry 2023-01, Vol.41 (2), p.181-187
• Main Authors: Fang, Songjia, Jiang, Huanfeng, Wu, Wanqing
• Format: Article
• Language: English
• Subjects: Amines; Assembly; Carbon; Chemical bonds; Cyclization; Functional groups; Haloalkynes; Halopyrroles; Insertion; N‐Alkylanilines; Palladium; Palladium‐catalyzed; Synthetic methods
• ISSN: 1001-604X; 1614-7065
• DOI: 10.1002/cjoc.202200422

Comprehensive Summary This report discloses a distinctive palladium‐catalyzed sequential tandem cyclization reaction of two molecular haloalkynes and one molecular N‐alkylanilines, leading to the efficient assembly of various 3‐halo‐1,2,5‐triarylpyrrole derivatives. Two carbon‐carbon triple bonds and one carbon‐halogen bond in two molecular haloalkynes are transformed conveniently in one single step, which may involve the aminoalkynylation of haloalkyne and cyclization of the newly formed enyne intermediate. The high chemo‐ and regioselectivities, good functional group tolerance and late‐stage modification of the halopyrrole products further illustrate the synthetic value of this strategy. An unprecedented palladium‐catalyzed three‐component tandem cyclization reaction of haloalkynes and N‐alkylaniline has been established for the efficient assembly of 3‐halo‐1,2,5‐triarylpyrroles. This protocol involves the sequential conversions of two carbon‐carbon triple bonds and one carbon‐halogen bond in two molecular haloalkynes and features convenient operation, high chemo‐ and regioselectivities, good functional group tolerance and various late‐stage modifications.