Various practical methods for the selective C−H functionalization of the ortho and recently also of the meta position of an arene have already been developed. Following our recent development of the directing-group-assisted para C−H functionalization of toluene derivatives, we herein report the first remote para C−H functionalization of phenol derivatives by using a recyclable silicon-containing biphenyl-based template. The effectiveness of this strategy was illustrated with different synthetic elaborations and by the synthesis of various phenol-based natural products.

Various practical methods for the selective C−H functionalization of the ortho and recently also of the meta position of an arene have already been developed. Following our recent development of the directing-group-assisted para C−H functionalization of toluene derivatives, we herein report the first remote para C−H functionalization of phenol derivatives by using a recyclable silicon-containing biphenyl-based template. The effectiveness of this strategy was illustrated with different synthetic elaborations and by the synthesis of various phenol-based natural products.

A CH activation strategy has been successfully employed for the high-yielding synthesis of a diverse array of 4-substituted 2-quinolinone species by a palladium-catalyzed dehydrogenative coupling involving diarylamines. This intermolecular annulation approach incorporates readily available α,β-unsaturated carboxylic acids as the coupling partner by suppressing the facile decarboxylation. Based on preliminary mechanistic studies, a reaction sequence is proposed, involving ortho palladation, π-coordination, β-migratory insertion, and β-hydride elimination.

A palladium-catalyzed CH activation strategy has been successfully employed for exclusive synthesis of a variety of 3-substituted indoles. A [3+3] annulation for synthesizing substituted 2-quinolinones was recently developed by reaction of α,β-unsaturated carboxylic acids with diarylamines under acidic conditions. In the present work, an analogous [3+2] annulation is achieved from the same set of starting materials under basic conditions to generate 1,3-disubstituted indoles exclusively. Mechanistic studies revealed an ortho-palladation–π-coordination–β-migratory insertion–β-hydride elimination reaction sequence to be operative under the reaction conditions.

Insertion of unsaturated systems such as alkynes and olefins into unactivated sp³ CH bonds remains an unexplored problem. We herein address this issue by successfully incorporating a wide variety of functionalized alkynes and electron-deficient olefins into the unactivated sp³ CH bond of pivalic acid derivatives with excellent syn- and linear- selectivity. A strongly chelating 8-aminoquinoline directing group proved beneficial for these insertion reactions, while an air-stable and inexpensive Ni^II salt has been employed as the active catalyst.

Divinylbenzene derivatives represent an important class of molecular building blocks in organic chemistry and materials science. Reported herein is the palladium-catalyzed synthesis of divinylbenzenes by meta-CH olefination of sulfone-based arenes. Successful sequential olefinations in a position-selective manner provided a novel route for the synthesis of hetero-dialkenylated products, which are difficult to access using conventional methods. Additionally, 1,3,5-trialkenylated compounds can be generated upon successful removal of the directing group.

Divinylbenzene derivatives represent an important class of molecular building blocks in organic chemistry and materials science. Reported herein is the palladium-catalyzed synthesis of divinylbenzenes by meta-CH olefination of sulfone-based arenes. Successful sequential olefinations in a position-selective manner provided a novel route for the synthesis of hetero-dialkenylated products, which are difficult to access using conventional methods. Additionally, 1,3,5-trialkenylated compounds can be generated upon successful removal of the directing group.

A copper-catalyzed method for synthesis of diaryl ketones (Ar-CO-Ar′) through removal of benzylic -CH₂-, -CO-, and -CHR- groups from Ar-CO-CXR-Ar′ has been discovered. A number of symmetrical and unsymmetrical heterocyclic ketones, which are usually difficult to synthesize, can be prepared in good to excellent yields. This method was applied to the synthesis of the nonsteroidal anti-inflammatory drug suprofen (47 % yield over three steps). Based on preliminary mechanistic and kinetic studies, an active Cu/O₂ species is proposed to mediate the rearrangement reaction.

A palladium-catalyzed dehydrogenative coupling between diarylamines and olefins has been discovered for the synthesis of substituted indoles. This intermolecular annulation approach incorporates readily available olefins for the first time and obviates the need of any additional directing group. An ortho palladation, olefin coordination, and β-migratory insertion sequence has been proposed for the generation of olefinated intermediate, which is found to produce the expected indole moiety.

A copper-catalyzed method for synthesis of diaryl ketones (Ar-CO-Ar′) through removal of benzylic -CH₂-, -CO-, and -CHR- groups from Ar-CO-CXR-Ar′ has been discovered. A number of symmetrical and unsymmetrical heterocyclic ketones, which are usually difficult to synthesize, can be prepared in good to excellent yields. This method was applied to the synthesis of the nonsteroidal anti-inflammatory drug suprofen (47 % yield over three steps). Based on preliminary mechanistic and kinetic studies, an active Cu/O₂ species is proposed to mediate the rearrangement reaction.

A palladium-catalyzed dehydrogenative coupling between diarylamines and olefins has been discovered for the synthesis of substituted indoles. This intermolecular annulation approach incorporates readily available olefins for the first time and obviates the need of any additional directing group. An ortho palladation, olefin coordination, and β-migratory insertion sequence has been proposed for the generation of olefinated intermediate, which is found to produce the expected indole moiety.

The present article describes novel oxidative protocols for direct esterification of alcohols. The protocols involve successful demonstrations of both “cross” and “self” esterification of a wide variety of alcohols. The cross-esterification proceeds under a simple transition-metal-free condition, containing catalytic amounts of TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy)/TBAB (tetra-n-butylammonium bromide) in combination with oxone (potassium peroxo monosulfate) as the oxidant, whereas the self-esterification is achieved through simple induction of Fe(OAc)₂/dipic (dipic=2,6-pyridinedicarboxylic acid) as the active catalyst under an identical oxidizing environment.

A sustainable FeCl₃-mediated method has been developed for the decarboxylative trifluoromethylation of α,β-unsaturated carboxylic acids by using NaSO₂CF₃ as an economic and stable CF₃ source. The reaction proceeds under mild condition and tolerates various functional groups. Advantageously, this method does not require an inert atmosphere and proceeds well in air at ambient temperature.

The arylation of C–H bonds to generate heteroaryl–aryl (Het–Ar) and arylated quinone (Quin–Ar) compounds has received great attention to achieve sustainable goals in synthetic chemistry. Despite significant advances, arylation of a broad range of Het–Ar and Quin–Ar derivatives remains a challenging task. Herein, a variety of heterocycles are arylated by using arylboronic acids in the presence of catalytic amounts of inexpensive Fe(NO₃)₃. The C-arylated quinone compounds can be prepared by reacting arylboronic acids with either quinone or hydroquinone. The present method is operationally simple, scalable, does not require prefunctionalization of the heterocycle or quinone, and can tolerate a wide variety of functional groups in the coupling partners. These qualities are expected to render this method attractive for academic and industrial use.