Room‐Temperature Palladium‐Catalyzed C?H Activation: ortho‐Carbonylation of Aniline Derivatives

Pd and CO—ureally got me! The title reaction proceeds efficiently at 18 °C under CO (1 atm) with 5 % [Pd(OTs)₂(MeCN)₂] as precatalyst. Depending on the solvents used, either anthranilates or cyclic imides can be obtained in high yields (see picture, BQ=benzoquinone, Ts=4‐toluenesulfonyl).

     

Palladium‐Catalyzed Direct C?H Functionalization of Benzoquinone

A direct Pd‐catalyzed C H functionalization of benzoquinone (BQ) can be controlled to give either mono‐ or disubstituted BQ, including the installation of two different groups in a one‐pot procedure. BQ can now be directly functionalized with aryl, heteroaryl, cycloalkyl, and cycloalkene groups and, moreover, the reaction is conducted in environmentally benign water or acetone as solvents.     

Ruthenium‐Catalyzed Cascade C?H Functionalization of Phenylacetophenones

Three orthogonal cascade C H functionalization processes are described, based on ruthenium‐catalyzed C H alkenylation. 1‐Indanones, indeno indenes, and indeno furanones were accessed through cascade pathways by using arylacetophenones as substrates under conditions of catalytic [{Ru(p‐cymene)Cl₂}₂] and stoichiometric Cu(OAc)₂. Each transformation uses C H functionalization methods to form C C bonds sequentially, with the indeno furanone synthesis featuring a C O bond formation as the terminating step. This work demonstrates the power of ruthenium‐catalyzed alkenylation as a platform reaction to develop more complex transformations, with multiple C H functionalization steps taking place in a single operation to access novel carbocyclic structures.     

Palladium‐Catalyzed C?H Fluorosilylation of 2‐Phenylpyridines: Synthesis of Silafluorene Equivalents

Treatment of 2‐phenylpyridines with amino(1,3,2‐dioxaborolan‐2‐yl)diphenylsilane produced fluorosilylated 2‐phenylpyridines in good to excellent yields under palladium catalysis. This reaction is the first example of C H fluorosilylation. Single‐crystal X‐ray structure analysis revealed a Lewis acid–base interaction between the silicon and nitrogen atoms, and the obtained fluorosilylated products are silafluorene equivalents. The fluorosilylated products showed stronger fluorescence than the corresponding silafluorene derivative.     

Double C?H Functionalization in Sequential Order: Direct Synthesis of Polycyclic Compounds by a Palladium‐Catalyzed C?H Alkenylation–Arylation Cascade

Palladium‐catalyzed cascade C? H alkenylation and arylation provides convenient access to polycyclic aromatic compounds. Treatment of 3‐bromoaniline derivatives bearing a bromocinnamyl group on the nitrogen atom with a catalytic amount of [Pd(OAc)₂] and PCy₃?HBF₄ in the presence of Cs₂CO₃ in dioxane affords naphthalene‐fused indole derivatives in good yields. This double cyclization reaction is also applicable to heterocyclic substrates, giving fused indoles containing a heteroaromatic ring such as dibenzofuran, dibenzothiophene, carbazole, indole, or benzofuran through heterocyclic C? H arylation. When using a 2,6‐unsubstituted aniline derivative, the first C? H arylation preferentially proceeds at the more hindered position of the aniline ring.     

Palladium‐Catalyzed Enantioselective C?H Arylation for the Synthesis of P‐Stereogenic Compounds

A palladium‐catalyzed enantioselective C H arylation of N‐(o‐bromoaryl)‐diarylphosphinic amides is described for the synthesis of phosphorus compounds bearing a P‐stereogenic center. The method provides good enantioselectivities and high yields. The products were readily transformed into P‐chiral biphenyl monophosphine ligands.     

Palladium‐Catalyzed ortho‐Selective C?H Deuteration of Arenes: Evidence for Superior Reactivity of Weakly Coordinated Palladacycles

We disclose a protocol for the palladium‐catalyzed ortho‐selective C H deuteration of arenes. Phenylacetic acids and benzoic acids are suitable substrates for this reaction. This reaction offers a catalytic route to ortho‐deuterated phenylacetic acids and benzoic acids and demonstrates the sharp difference in reactivity of palladacycle intermediates held together by weak and strong coordination.     

Intermolecular Domino Reaction of Two Aryl Iodides Involving Two C?H Functionalizations

A palladium‐catalyzed intermolecular cross‐coupling of two aryl iodides is reported, giving polycyclic ring systems with a high level of convergence and efficiency.     

Iron‐Catalyzed Chemoselective ortho Arylation of Aryl Imines by Directed C?H Bond Activation

No Fe‐ar : Iron catalyzes an imine‐directed C? H bond activation to introduce an ortho‐aryl group to an acetophenone‐derived imine using a diarylzinc reagent (see scheme), whereas palladium catalyzes the conventional substitution reaction . The title reaction features mild and selective C? H bond activation in the presence of aryl bromide, chloride, or sulfonate groups, and 1,2‐dichloroisobutane is essential to achieve such selectivity.