Palladium-Catalyzed Formal Cross-Coupling of Diaryl Ethers with Amines: Slicing the 4-<i>O</i>
-5 Linkage in Lignin Models
作者:Huiying Zeng、Dawei Cao、Zihang Qiu、Chao-Jun Li
DOI:10.1002/anie.201712211
日期:2018.3.26
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
Formal Cross-Coupling of Diaryl Ethers with Ammonia by Dual C(Ar)–O Bond Cleavages
作者:Dawei Cao、Huiying Zeng、Chao-Jun Li
DOI:10.1021/acscatal.8b02214
日期:2018.9.7
inorganic chemical. Herein, we report a direct conversion of diaryl ethers and ammonia into aniline derivatives and arenes, providing a model for selective lignin 4-O-5 linkage modification and PPO recycling with inexpensive ammonia. Both symmetrical and unsymmetrical diaryl ethers were successfully cross-coupled with ammonia via dual C(Ar)–O bond cleavages, generating the corresponding cyclohexylanilines
Organocatalyzed Birch Reduction Driven by Visible Light
作者:Justin P. Cole、Dian-Feng Chen、Max Kudisch、Ryan M. Pearson、Chern-Hooi Lim、Garret M. Miyake
DOI:10.1021/jacs.0c05899
日期:2020.8.5
The Birchreduction is a powerful synthetic methodology that uses solvated electrons to convert inert arenes to 1,4-cyclohexadienes-valuable intermediates for building molecular complexity. Birchreductions traditionally employ alkali metals dissolved in ammonia to produce a solvated electrons for the reduction of unactivated arenes such as benzene (Ered < -3.42 V vs. SCE). Photoredox catalysts have
Birch 还原是一种强大的合成方法,它使用溶剂化电子将惰性芳烃转化为 1,4-环己二烯有价值的中间体,以构建分子复杂性。桦木还原传统上使用溶解在氨中的碱金属来产生溶剂化电子,用于还原未活化的芳烃,例如苯(Ered < -3.42 V vs. SCE)。光氧化还原催化剂在高度还原应用中越来越受欢迎,但没有报道显示出足以减少苯的还原潜力。在这里,我们引入苯并苝酰亚胺作为新型有机光氧化还原催化剂,用于在环境温度下进行桦木还原,并由市售 LED 的可见光驱动。使用低催化剂负载量(<1 摩尔百分比),在完全无金属的反应中,苯和其他官能化芳烃以中等至良好的产率选择性地转化为 1,4-环己二烯。机理研究表明,这种前所未有的可见光诱导反应是通过有机光氧化还原催化剂利用两个可见光光子的能量影响单个高能化学转化的能力实现的。
CuI/<i>N</i>,<i>N</i>-Dimethylglycine-Catalyzed Cross-Coupling Reaction of Vinyl Halides with Phenols and its Application to the Assembly of Substituted Benzofurans
作者:Dawei Ma、Qian Cai、Xiaoan Xie
DOI:10.1055/s-2005-871543
日期:——
Cul-catalyzed coupling reaction of vinylhalides and phenols occurs at 60-90 °C with N,N-dimethylglycine hydrochloride as the additive, giving vinylarylethers in good yields. The cross-coupling products formed from o-iodophenols and vinyl iodides are converted into substituted benzofurans via an intramolecular Heck reaction.
Cul 催化的卤乙烯和苯酚的偶联反应在 60-90 °C 下发生,N,N-二甲基甘氨酸盐酸盐作为添加剂,以良好的收率得到乙烯基芳基醚。由邻碘苯酚和乙烯基碘形成的交叉偶联产物通过分子内 Heck 反应转化为取代的苯并呋喃。
Method to convert lignin 4-O-5 diaryl ethers and their model compounds into organic chemicals
申请人:LANZHOU UNIVERSITY
公开号:US10766851B1
公开(公告)日:2020-09-08
It is provided a method of converting a diaryl ether source such as lignin and/or polyphenylene oxide (PPO) containing 4-O-5 linkages and an inorganic chemical such as ammonia into an organic compound, comprising reacting said diaryl ether source with the inorganic chemical in presence of a catalyst, preferably palladium, transforming the 4-O-5 linkages of said diaryl ether source into the organic compound. It is provided a palladium-catalyzed synthesis of aniline derivatives from 4-O-5 linkage lignin model compounds and cheap industrial inorganic chemical ammonia via dual C(Ar)—O bond cleavage.