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Easy Access to 2,4-Disubstituted Cyclopentenones by a Gold(III)-Catalyzed A3-Coupling/Cyclization Cascade

Jian Li*, Yue Xu, Xiwen Hu, Shangrong Zhu and Li Liu*

*Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, School of Pharmacy, Changzhou University, Changzhou, 213164, China, Email: liliucczu.edu.cn

J. Li, Y. Xu, X. Hu, S. Zhu, L. Liu, Org. Lett., 2020, 22, 9478-9483.

DOI: 10.1021/acs.orglett.0c03451


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Abstract

A Au(III)-catalyzed isomerization-A3-coupling/cyclization cascade enables an efficient and convenient synthesis of 2,4-disubstituted cyclopentenones.

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Details

The document discusses a novel method for synthesizing 2,4-disubstituted cyclopentenones using a gold(III)-catalyzed isomerization−A3-coupling/cyclization cascade. This method is efficient and convenient, utilizing readily available alkynes, aldehydes, and amines under mild conditions. The process involves an initial Au(III)-catalyzed isomerization, followed by an A3-type coupling and cyclization via an enol intermediate. The use of trifluoroethanol (TFE) as a solvent is crucial for achieving the desired chemoselectivity. The study optimized reaction conditions, finding that AuBr3 in TFE at 60°C for 24 hours provided the best yields. Various secondary amines and terminal arylalkynes were tested, showing good tolerance and yielding the desired cyclopentenone products in moderate to good yields. The proposed mechanism involves the formation of an iminium ion enol, which reacts with a gold-activated alkyne to form propargylamines, followed by cyclization to yield the final product. The method offers a straightforward and versatile approach to synthesizing cyclopentenones, which are valuable synthetic intermediates in organic chemistry. Further studies are ongoing to explore the potential of this method for synthesizing other complex molecules.


Key Words

Cyclopentenones, Multicomponent Reactions


ID: J54-Y2020