In this article, the structurally well-defined dinuclear complex copper(I) acetate was studied in detail and was developed as a highly practical and efficient catalyst for the copper(I)-catalyzed azide-alkyne cycloaddition. The "bare" phenylethynylcopper(I) (i.e., with no exogeneous ligands) was isolated as an intermediate, which can be converted into an active catalytic species by treatment with acetic acid (in situ produced in the reaction) to efficiently catalyze the azide-alkyne cycloaddition under mild conditions.

A general and efficient procedure for the preparation of phenols was developed by copper-catalyzed oxidative hydroxylation of arylboronic acids at room temperature in water.

Pd(II)-catalyzed ortho-alkylation of benzoic acids with both terminal and internal epoxides affords 3,4-dihydroisocoumarins in one step. The presence of potassium countercations is crucial for this reaction. Monoprotected amino acid ligands significantly promote this reaction, enabling the development of a practical C-H alkylation reaction using 0.5 mol % Pd catalyst. The inversion of stereochemistry in the C-H alkylation step is consistent with a redox-neutral SN2 nucleophilic ring-opening process as opposed to a Pd(II)/Pd(IV) pathway.

A Pd-catalyzed, meta-selective C−H arylation of nosyl-protected phenethylamines, and benzylamines is disclosed using a combination of norbornene and pyridine-based ligands. Subjecting 2-aryl anilines to this protocol lead to meta-C–H arylation at the remote aryl ring. A diverse range of aryl iodides are tolerated in this reaction, along with select heteroaryl iodides. Select aryl bromides bearing ortho-coordinating groups can also be utilized as effective coupling partners in this reaction. The use of pyridine ligands has allowed the palladium loading to be reduced to 2.5 mol%. Furthermore, a catalytic amount of 2-norbornene (20 mol%) to mediate this meta-C–H activation process is demonstrated for the first time. Utilization of a common protecting group as the directing group for meta-C–H activation of amines is an important feature of this reaction in terms of practical applications.

A palladium-catalyzed ortho-silylation of aryl iodides/arylsilylation of oxanorbornadiene/retro-Diels-Alder domino reaction was developed. Such a transformation provides access to various functionalized ( Z)-β-substituted vinylsilanes with exclusive selectivity using hexamethyldisilane as a bis-silylation reagent and 2,3-dicarbomethoxy-7-oxanorbornadiene (ONBD) as an ortho-C-H activator and ethylene surrogate. A variety of ( Z)-β-substituted vinylgermanes and ( Z)-β-substituted vinylstannanes were also obtained under mild reaction conditions. This atom-economical, stereoselective, and scalable approach is compatible with a diverse range of readily available functionalized aryl iodides.

About specifics: A method for the regiospecific synthesis of the title compounds through an unprecedented Michael addition/deacylative diazo transfer/cyclization sequence has been established. The simple and practical method can be used for the modification of primary amines including chiral α‐amines. The process involves the formation three covalent bonds and the cleavage of two covalent bonds (see scheme, Ts=4‐toluenesulfonyl).

Palladium(II)-catalyzed meta-C–H arylation and alkylation of benzylsulfonamide using 2-carbomethoxynorbornene (NBE-CO2Me) as a transient mediator are realized using a newly developed electron-deficient directing group and isoquinoline as a ligand. This protocol features broad substrate scope and excellent functional group tolerance. The meta-substituted benyzlsulfonamide can be readily transformed to sodium sulfonate, sulfonate ester, sulfonamide, as well as styrenes via Julia-type olefination. The unique impact of the isoquinoline ligand underscores the importance of subtle matching between ligands and the directing groups.

In this work, we describe a Catellani-type C−H glycosylation to provide rapid access to various highly decorated α-C-(hetero)aryl glycosides in a modular and stereoselective manner (>90 examples). The termination step is flexible, which is demonstrated by ipso-Heck reaction, hydrogenation, Suzuki coupling, and Sonogashira coupling. Application of this methodology has been showcased by preparing glycoside−pharmacophore conjugates and a dapagliflozin analogue. Notably, the technology developed herein represents an unprecedented example of Catellani-type alkylation involving an S N 1 pathway.