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Chiral Bifunctional Phosphine Ligand-Enabled Cooperative Cu Catalysis: Formation of Chiral α,β-Butenolides via Highly Enantioselective γ-Protonation

Xinpeng Cheng, Tianyou Li, Kaylaa Gutman and Liming Zhang*

*Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California 93106, United States, Email: zhangchem.ucsb.edu

X. Cheng, T. Li, K. Gutman, L. Zhang, J. Am. Chem. Soc., 2021, 143, 10876-10881.

DOI: 10.1021/jacs.1c05781


Abstract

A Cu(I)-ligand cooperative catalysis enables the synthesis of α,β-butenolides with ≥96% enantiomeric excess from β,γ-butenolides. The chiral biphenyl-2-ylphosphine ligand features a remote tertiary amino group. DFT studies support the cooperation between the metal center and the ligand basic amino group during the initial soft deprotonation and the key asymmetric γ-protonation.

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Synthesis of α,β-butenolides:

To a 2-dram vial with substrate (0.3 mmol) under argon protection, [(S)-L2Cu(MeCN)]+PF6- (13.8 mg, 5 mol %) in 1.2 mL DCM was added and the reaction solution was stirred at room temperature for the indicated time. The solvent was removed, and the residue was purified by flash column chromatography (hexanes/EtOAc = 10/1, 7/1, or 5/1) to afford the desired product.


Asymmetric Construction of α,γ-Disubstituted α,β-Butenolides Directly from Allylic Ynoates Using a Chiral Bifunctional Phosphine Ligand Enables Cooperative Au Catalysis

T. Li, S. Dong, C. Tang, M. Zhu, N. Wang, W. Kong, W. Gao, J. Zhu, L. Zhang, Org. Lett., 2022, 24, 4427-4432.


Key Words

butenolides


ID: J48-Y2021