Specific Z-Selectivity in the Oxidative Isomerization of Allyl Ethers to Generate Geometrically Defined Z-Enol Ethers Using a Cobalt(II)(salen) Complex Catalyst

Guanxin Huang; Miaolin Ke; Yuan Tao; Fener Chen

doi:10.1021/acs.joc.0c00004

Specific Z-Selectivity in the Oxidative Isomerization of Allyl Ethers to Generate Geometrically Defined Z-Enol Ethers Using a Cobalt(II)(salen) Complex Catalyst

J Org Chem. 2020 Apr 17;85(8):5321-5329. doi: 10.1021/acs.joc.0c00004. Epub 2020 Apr 8.

Authors

Guanxin Huang^{1

2}, Miaolin Ke^{1

2}, Yuan Tao^{1

2}, Fener Chen^{1

2

3}

Affiliations

¹ Engineering Center of Catalysis and Synthesis for Chiral Molecules, Department of Chemistry, Fudan University, Shanghai 200433, P. R. China.
² Shanghai Engineering Center of Industrial Asymmetric Catalysis for Chiral Molecules, Shanghai 200433, P. R. China.
³ Institute of Pharmaceutical Science and Technology, Zhejiang University of Technology, 18 Chao Wang Road, Hangzhou 310014, China.

PMID: 32208604
DOI: 10.1021/acs.joc.0c00004

Abstract

Enol ether structural motifs exist in many highly oxygenated biologically active natural products and pharmaceuticals. The synthesis of the geometrically less stable Z-enol ethers is challenging. An efficient Z-selective oxidative isomerization process of allyl ethers catalyzed by a cobalt(II) (salen) complex using N-fluoro-2,4,6-trimethylpyridinium trifluoromethanesulfonate (Me₃NFPY•OTf) as an oxidant has been developed. Thermodynamically less stable Z-enol ethers were prepared in excellent yields with high geometric control. This methodology also demonstrates the effectiveness in controlling the Z-selective isomerization reaction of diallyl ethers at room temperature. This catalytic system provides an alternative pathway to extend the traditional reductive isomerization of allyl ethers.