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Direct C–H amination methods are essential because of the importance of aryl amine derivatives.

1,10-Phenanthroline-assisted, Ni(ii)-catalyzed para-carboxylation of phenol derivatives is reported.

We report the para-selective C–H benzylation of phenyl carbamate with an iron(II) catalyst. This new method provides an efficient and convenient approach for the synthesis of triarylmethanes starting from readily available anilines and diphenylmethane. Preliminary mechanistic studies revealed that the iron(II) catalyst was essential and the use of the sterically demanding isobutoxy group led to high para-selectivity.

A convenient approach to synthesize o-hydroxybenzylamine via Pd-catalyzed hydroxylation of benzylamine with a removable Cbz-amide as the directing group was developed. Various functional groups were well tolerated, leading to various substituted o-hydroxybenzylamines in moderate to good yields.

A regioselective rhodium-catalyzed carboxylate-directed thiolation process was developed. Several benzoic-acid derivatives and disulfides were found to be well-tolerated, and they yielded the corresponding products in moderate to good yields. Compounds such as the key precursor of roflumilast can be obtained via this reaction, thereby highlighting the potential of this synthetic approach.

A highly efficient silver-catalyzed dibenzylation of acetanilides by employing the benzhydrol derivatives as the coupling partners to yield triphenylmethane derivatives has been developed. Various functional groups were tolerated, leading to the corresponding products in moderate to good yields. Preliminary experimental results indicated that the silver ions activate the arene rings and the strong acid TfOH provides the carbocations.

The first example of employing thiophene as the coordination center to assist C–H functionalization via a palladium catalyst has been described. The synthetically challenging penta-substituted benzylamines with five different functional groups could be easily achieved by taking advantage of transitive oxalyl amide/thiophene-directed C–H functionalization, which highlights its versatility in the construction of multiply-substituted arenes. The penta-substituted benzylamine displays its potential nature as a hole-transporting material.

Oxindole/isatin-N-acetamide derivatives are a class of important pharmacologically active compounds. Herein, we report a practical protocol for the synthesis of such derivatives based on palladium-catalyzed intramolecular amination. Various functional groups are tolerated, and the corresponding products are obtained in moderate to good yields, highlighting the potential synthetic utility of this method.

A ruthenium-enabled meta-selective C–H difluoromethylation of arenes has been developed. Various arenes bearing pyridyl, pyrazolyl, imidazolyl, or pyrimidyl directing groups, or removable oxazoline directing groups, were tolerated in this meta-selective C–H difluoromethylation, affording the difluoromethylated products in moderate to good yields. The difluoromethyl group could be selectively installed into several drug molecules and bioactive compounds in one step, highlighting the synthetic utility and importance of this new method.

Palladium-catalyzed ortho-alkynylation of arylalkylacid derivatives at remote γ and δ positions with the assistance of an N,O-bidentate directing group of glycine dimethylamide (GDMA) is reported for the first time. A wide variety of phenylacetic acid and 3-phenylpropionic acid derivatives is tolerated in this protocol, which provides a general means to synthesize substituted alkynylarylalkyl acid derivatives.

A novel Pd(OAc)2/Ag2CO3-catalyzed coupling reaction was investigated. Substituted 3-benzylidene-2-arylisoindolin-1-ones were reacted with diphenylphosphine oxide to afford 3-arylidene-2-(2-(diphenylphosphoryl)aryl)isoindolin-1-ones. The reaction proceeded at 25 °C in an air atmosphere in the absence of base and ligands. Our results indicate that the diphenylphosphine oxide free radical tends to attack the aryl rather than the double bond in this reaction.

Direct transformation of a directing group to important synthetic units would provide a high atom efficiency synthetic approach in synthetic chemistry. Herein, a convenient protocol for the synthesis of o-aminobenzaldehyde and benzoxazole derivatives from benzyl alcohols has been developed by employing (N,N-dimethyl)oxamoyl amide as a directing group in a palladium-catalyzed intramolecular amination. Furthermore, the attached directing center may not only be transformed into the product, but may also be further applied to generate synthetically important quinazoline and quinoline units. Finally, a high atom efficiency one-pot, two-step approach to form quinazolines from benzyl alcohol derivatives has been achieved in good yields, thus demonstrating its high utility.

A highly efficient and practical Ru-catalyzed direct C–H functionalization of indolines and N-alkylaniline with a simple pivaloyl as a directing group is developed. Broad substrate scopes with respect to N-heteroarenes and olefins are observed. The selective C7-position alkynylation for indoline also proceeds well by using inexpensive ruthenium as a catalyst, and pivaloyl as a directing group.

The first Pd-catalyzed regioselective γ-carbonylation of oxalyl amide protected aliphatic amines with carbon monoxide leading to synthesis of pyrrolidones has been developed. Both γ-methyl and cyclopropyl methylene C–H bonds are well activated to obtain the corresponding pyrrolidones in moderate to excellent yields. The role of 3-(trifluoromethyl)benzoic acid as an additive is critical as it helps in stabilizing the palladium intermediate formed during the catalytic cycle. The reaction scope is extended to benzylamine and allyl amine derivatives, thereby affording the corresponding products in good to excellent yields.

Palladium-catalyzed oxalyl amide directed ortho-alkynylation of arylalkylamine derivatives is reported for the first time. A wide variety of β-arylethamine and γ-arylpropamine derivatives are compatible with this protocol. This method provides a general means to synthesize substituted alkynylarylalkylamine derivatives, highlighting the ability of oxalyl amide in promoting C-H functionalization at unique δ and ε positions.

A protocol for palladium-catalyzed ortho C(sp2)–H alkenylation via a rarely reported seven-membered palladacycle with oxalyl amide as a directing group was reported. The range of olefins was the broadest yet reported for this kind of C–H alkenylation reaction. For example, allyl acetate, allyl alcohol derivatives, acraldehyde, acrylate and acrylonitrile were all tolerated in this C–H transformation. Sequential alkenylation reactions were also achieved to construct the complex olefinated arenes in good yields in one pot.

A highly efficient and practical organic solvent-free Cu(OAc)2/DMAP/TEMPO catalyst system for the selective aerobic oxidation of benzylic and allylic alcohols to aldehydes and phenones under an ambient air atmosphere was reported. A wide range of functional groups such as phenolic hydroxyl, amino, and methylthio are compatible with the catalyst system. The organic solvent-free aerobic oxidative imine synthesis from benzyl alcohol and amines was also achieved via the newly developed Cu(OAc)2/DMAP/TEMPO catalyst. 100 g-scale reactions for aldehyde and imine formation were achieved with over 90% yield using 0.5 mol% catalyst loading in 36 hours, presenting a potential valuable protocol for both economical and environmental considerations.