Volume 57, Issue 14 pp. 3752-3757
Communication

Palladium-Catalyzed Formal Cross-Coupling of Diaryl Ethers with Amines: Slicing the 4-O-5 Linkage in Lignin Models

Prof. Dr. Huiying Zeng

Corresponding Author

Prof. Dr. Huiying Zeng

The State Key Laboratory of Applied Organic Chemistry, Lanzhou University, 222 Tianshui Road, Lanzhou, 730000 P. R. China

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Dawei Cao

Dawei Cao

The State Key Laboratory of Applied Organic Chemistry, Lanzhou University, 222 Tianshui Road, Lanzhou, 730000 P. R. China

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Zihang Qiu

Zihang Qiu

Department of Chemistry and FQRNT Centre for Green Chemistry and Catalysis, McGill University, 801 Sherbrooke St. West, Montreal, Quebec, H3A 0B8 Canada

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Prof. Dr. Chao-Jun Li

Corresponding Author

Prof. Dr. Chao-Jun Li

The State Key Laboratory of Applied Organic Chemistry, Lanzhou University, 222 Tianshui Road, Lanzhou, 730000 P. R. China

Department of Chemistry and FQRNT Centre for Green Chemistry and Catalysis, McGill University, 801 Sherbrooke St. West, Montreal, Quebec, H3A 0B8 Canada

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First published: 31 January 2018
Citations: 111

Graphical Abstract

From waste to value: A strategy for converting renewable lignin biomass into value-added nitrogen-containing chemicals is reported. Model compounds of lignin containing a 4-O-5 linker were cross-coupled with amines by dual C(Ar)−O bond cleavages to generate valuable nitrogen-containing derivatives.

Abstract

Lignin is the second most abundant organic matter on Earth, and is an underutilized renewable source for valuable aromatic chemicals. For future sustainable production of aromatic compounds, it is highly desirable to convert lignin into value-added platform chemicals instead of using fossil-based resources. Lignins are aromatic polymers linked by three types of ether bonds (α-O-4, β-O-4, and 4-O-5 linkages) and other C−C bonds. Among the ether bonds, the bond dissociation energy of the 4-O-5 linkage is the highest and the most challenging to cleave. To date, 4-O-5 ether linkage model compounds have been cleaved to obtain phenol, cyclohexane, cyclohexanone, and cyclohexanol. The first example of direct formal cross-coupling of diaryl ether 4-O-5 linkage models with amines is reported, in which dual C(Ar)−O bond cleavages form valuable nitrogen-containing derivatives.

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