A New Method for Aromatic Difluoromethylation: Copper-Catalyzed Cross-Coupling and Decarboxylation Sequence from Aryl Iodides
摘要:
A new methodology for aromatic difluoromethylation is described. Aryl iodides reacted with alpha-silyldifluoroacetates upon treatment with copper catalyst in DMSO or DME to give the corresponding aryldifluoroacetates in moderate to good yields. The subsequent hydrolysis of aryldifluoroacetates and KF-promoted decarboxylation afforded a variety of difluoromethyl aromatics.
Proton Magnetic Resonance Studies of Rotational Isomerism in Halotoluenes. X. Estimates of Conformational Preferences and Rotational Barriers in Benzal Fluoride and Some Dichloro Derivatives
作者:J. Brian Rowbotham、Alexander Frank Janzen、James Peeling、Ted Schaefer
DOI:10.1139/v74-077
日期:1974.2.1
4-, and 2,4-dichloro derivatives is followed by an analysis of their proton magnetic resonance spectra. The long-range spin–spin coupling constants are most consistent with a barrier to rotation about the sp2–sp3 carbon–carbon bond in benzal fluoride of less than 500 cal/mol, in semiquantitative agreement with an ab initio molecular orbital calculation. The 2,6-dichloro derivative has a conformation
在合成苯并氟及其 2,6-、3,5-、3,4- 和 2,4-二氯衍生物之后,对其质子磁共振光谱进行了分析。长程自旋-自旋耦合常数与小于 500 cal/mol 的苯甲醛中 sp2-sp3 碳-碳键的旋转势垒最一致,与 ab initio 分子轨道计算半定量一致。2,6-二氯衍生物具有侧链的CH键位于芳环平面的构象。2,4-二氯衍生物有利于类似的构象,CH键与环氯原子顺式排列。与长程质子 - 质子偶联相反,长程质子 - 氟偶联本质上对环氯原子的取代基效应敏感。
Nickel-Catalyzed Difluoromethylation of Arylboronic Acids with Bromodifluoromethane
作者:Xia-Ping Fu、Yu-Lan Xiao、Xingang Zhang
DOI:10.1002/cjoc.201700624
日期:2018.2
fluorine source, direct formation of difluoromethylated arenes with BrCF2H has not been reported. Herein, we describe an efficient method to access difluoromethylated arenes through a nickel‐catalyzeddifluoromethylation of arylboronic acids with BrCF2H. The reaction exhibits high efficiency, good functional group tolerance and broad substrate scope, thus providing an efficient route for applications in
Synthesis, Reactivity, and Catalytic Applications of Isolable (NHC)Cu(CHF<sub>2</sub>) Complexes
作者:James R. Bour、Stavros K. Kariofillis、Melanie S. Sanford
DOI:10.1021/acs.organomet.7b00025
日期:2017.4.10
Difluoromethyl copper complexes have been proposed as key intermediates in a variety of Cu-catalyzed difluoromethylation reactions. However, studies of these putative intermediates have been impeded by the low stability of these [Cu(CHF2)] species. This report describes the synthesis of isolable N-heterocyclic carbene ligated copper(I) difluoromethyl complexes. The stoichiometric reactions of these complexes with aryl electrophiles (i.e., diaryliodonium salts, aryl iodides, and aryl bromides) are described. In addition, N-heterocyclic carbene copper(I) species are demonstrated to serve as catalysts for the cross-coupling of aryl iodides with (difluoromethyl)trimethylsilane to afford difluoromethyl arene products.