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Palladium‐Catalyzed Formal Cross‐Coupling of Diaryl Ethers with Amines: Slicing the 4‐ O ‐5 Linkage in Lignin Models
Author(s) -
Zeng Huiying,
Cao Dawei,
Qiu Zihang,
Li ChaoJun
Publication year - 2018
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201712211
Subject(s) - chemistry , lignin , ether , organic chemistry , bond cleavage , silyl ether , catalysis , silylation
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.