Photocatalytic Phenol–Arene C–C and C–O Cross‐Dehydrogenative Coupling

Abstract

Phenol-containing nonsymmetrical biaryls play an important role in natural-product synthesis, as ligands in metal catalysis, and in organic functional materials. Their synthesis through cross-coupling reactions by two-fold direct C-H activation are important and challenging transformations. In the last decade, a variety of useful oxidative methods have been developed. The key to efficiency and selectivity typically is the application of highly fluorinated solvent systems. Herein, we describe the visible-light-mediated C-C and C-O cross-coupling of electron-rich phenols and arenes by using [Ru(bpz) 3 ](PF 6 ) 2 ]

Cu‐Catalyzed Cross‐Dehydrogenative ortho‐Aminomethylation of Phenols

“…[3] Thedevelopment of useful intermolecular CDCs,h owever,i sa ssociated with considerable challenges,such as regioselectivity or undesired homocoupling processes.I no rder to intercept the oxidation of the most electron-rich coupling partner into atrue heterocoupling process,o ne can resort to substrate bias (i.e., sterics). [4] Alternatively,o ne can utilize metal catalysis in order to control the various competing oxidation pathways, and thereby escape the narrow substrate specificity often imposed by metal-free systems.H erein, we propose such as trategy through the Cu II -catalyzed cross-dehydrogenative ortho-aminomethylation of phenols [5,6] with aniline derivatives (Scheme 1a nd Scheme 2).…”

“…This method represents ar are case of C(sp 2 )ÀC(sp 3 )C DC with phenols. [6] This unusual dehydrogenative process is anticipated to lead to the development of other general classes of CÀCb ond forming CDC reactions.F urther mechanistic investigations may be necessary in order to rationally achieve those objectives.…”

Total Synthesis of Pyrolaside B: Phenol Trimerization through Sequenced Oxidative C−C and C−O Coupling

“…Other bulky para-alkyl groups are tolerated but give low yields (cf. 20,[22][23][24][25]. On the other hand, 2,4-dimethylphenol, 2-methyl-4-isopropylphenol, 2methyl-4-chlorophenol, and 2-methyl-4-dimethylaminophenol resulted in decomposition.…”

Synthetische Photoelektrochemie

“…The elucidation of such precomplexation mechanisms presents a challenge and demands the use of advanced spectroscopic, spectroelectrochemical and theoretical (computational) tools. 84,85 The ability to generate super oxidants and super reductants in situ and within close proximity to the substrate of interest (via PECatsubstrate precomplexation) may allow redox process to take place at potentials beyond those available from PRC and beyond those normally tolerable by the organic solvent in which the reaction takes place (Figure 20). Thereby, e-PRC may allow a 'realm' for extremely challenging SET processes such as direct oxidations of carbonyls, sulfones, fluorinated aromatics and hydrocarbons.…”