Oxidative Coupling of Benzenes with α,β-Unsaturated Aldehydes by the Pd(OAc)2/Molybdovanadophosphoric Acid/O2 System

Rhodium-Catalyzed Enal Transfer with N-Methoxypyridazinium Salts

Herein, we report a simple method for functionalized enals involving enal-transfer reaction of water-soluble N-methoxypyridazinium salts. This open-flask reaction proceeds under mild aqueous basic conditions through [2,3]-sigmatropic rearrangement of propargyl/allyl sulfur-ylides derived from in situ-generated Rh-(E)-enalcarbene. Various synthetically challenging allene- and allyl-functionalized (E)-enals with a γ-C(sp³) quaternary center were obtained in good to high yields. InCl₃-catalyzed cascade cyclization of allenyl-enal and aniline gave a valuable pyrrolo[1,2-a]quinoline motif.

Palladium-catalyzed C–H olefination of uracils and caffeines using molecular oxygen as the sole oxidant

The palladium-catalyzed oxidative C–H olefination of uracils or caffeines with alkenes using an atmospheric pressure of molecular oxygen as the sole oxidant has been disclosed.

Palladium catalysed meta-C–H functionalization reactions

The directing group assisted site selective C–H functionalization approach is having a continuous impact in the field of natural product synthesis, drug discovery and material sciences.

Gold(i) catalyzed [1,3] O → C rearrangement of benzylvinyl ethers

A simple procedure for the preparation of 3-(hetero)arylpropionaldehydes has been developed employing a gold-catalyzed [1,3]-rearrangement of vinyl ethers.

An Efficient TiCl4-Catalysed Method for the Synthesis of Para-Substituted Aromatic Aldehydes

An efficient and highly selective synthesis of para-substituted aromatic aldehydes has been achieved by TiCl4-catalysed Friedel–Crafts alkylation of monosubstituted benzenes with methacrolein diacetyl acetal.

Preparation of tetrasubstituted olefins using mono or double aerobic direct C-H functionalization strategies: importance of steric effects

A novel protocol for the synthesis of tetrasubstituted olefins through a biomimetic approach has been explored. Both mono- and diarylations were performed under ambient oxygen pressure, giving a range of highly hindered tetrasubstituted alkenes. For diarylation of disubstituted substrates, it was demonstrated that the second arylation is the rate-limiting step of the overall transformation.

Pd(II)/HPMoV-catalyzed direct oxidative coupling reaction of benzenes with olefins

The direct aerobic coupling reaction of arenes with olefins was successfully achieved by the use of Pd(OAc)₂/molybdovanadophosphoric acid (HPMoV) as a key catalyst under 1 atm of dioxygen. This catalytic system could be extended to the coupling reaction of various substituted benzenes with olefins such as acrylates, aclrolein, and ethylene through the direct aromatic C-H bond activation.

Waste-free synthesis of condensed heterocyclic compounds by rhodium-catalyzed oxidative coupling of substituted arene or heteroarene carboxylic acids with alkynes

The direct oxidative coupling of 2-amino- and 2-hydroxybenzoic acids with internal alkynes proceeds efficiently in the presence of a rhodium/copper catalyst system under air to afford the corresponding 8-substituted isocoumarin derivatives, some of which exhibit solid-state fluorescence. Depending on conditions, 4-ethenylcarbazoles can be synthesized selectively from 2-(arylamino)benzoic acids. The oxidative coupling reactions of heteroarene carboxylic acids as well as aromatic diacids with an alkyne are also described.

C-C bond formation via double C-H functionalization: aerobic oxidative coupling as a method for synthesizing heterocoupled biaryls

The aerobic oxidative coupling of arenes such as benzofuran and N-substituted indoles with benzene and derivatives thereof is described. The reaction is shown to take place in both inter- and intramolecular scenarios.