C(sp2)-H Acylation of benzo[h]quinolines at Room Temperature via Aldehyde Autoxidation and Palladium Catalysis Cooperation.

Herein, we report Pd-catalyzed C(sp2)-H acylation using aldehyde as acyl source and O2 as the green oxidant at room temperature. A selective association of acyl radical formed in-situ during aldehyde autoxidation with Pd-catalysis is the key to the process. The reaction afforded products in good yields (up to 82%) and it is scalable.

Aziridine Group Transfer via Transient -Aziridinyl Radicals.

Aziridines are the smallest nitrogen-containing heterocycles. Strain-enhanced electrophilicity renders aziridines useful synthetic intermediates and gives rise to biological activity. Classical aziridine syntheses─based on either [2 + 1] cycloadditions or intramolecular substitution chemistry─assemble aziridines from acyclic precursors.

β-Phenethylamine Synthesis: N-Pyridinium Aziridines as Latent Dual Electrophiles.

β-Phenethylamines are widely represented in biologically and pharmacologically active organic small molecules. Here, we introduce N-pyridinium aziridines as latent dual electrophiles for the synthesis of β-phenethylamines. Bromide-promoted ring opening generates β-halopyridinium amines.

Brønsted Acid-Promoted Intermolecular Dearomative Photocycloaddition of Bicyclic Azaarenes with Olefins under Aerobic Conditions.

Herein, we present a simplified reaction protocol for the dearomatization of bicyclic azaarenes via photochemical cycloaddition with alkenes using an Ir(III) photosensitizer, trifluoroacetic acid (TFA), dichloroethane, and a blue light-emitting diode. An efficient protonation of azaarenes with TFA enhances the reactivity of triplet azaarene toward olefins, enabling the photocycloaddition under aerobic conditions. The protocol applies to a broad range of substrates.

Heteroarylation of Ethers, Amides, and Alcohols with Light and O.

An efficient protocol for the C-H heteroarylation of ethers, amides, and alcohols using air and light under mild conditions is described. The reaction is applicable to a wide spectrum of functional groups. The generation of C-radicals via photoinduced aerobic oxidation of ethers, amides, and alcohols is the key feature of the process.

Aerobic Acylarylation of α,β-Unsaturated Amides with Aldehydes.

Herein, we illustrate that molecular oxygen (O) is capable of promoting oxidative radical acylarylation of olefins with aliphatic aldehydes to afford acylated oxindoles in good yield (up to 97%). The key aspect of the process is the utilization of aldehyde auto-oxidation in developing aerobic radical olefin acylarylation. Kinetic studies confirm a lag phase for the reaction.

Palladium-Catalyzed Decarboxylative ortho-C(sp )-H Aroylation of N-Sulfoximine Benzamides at Room Temperature.

A palladium-catalyzed method for the decarboxylative ortho C-H acylation of N-sulfoximine benzamides is developed at room temperature. The catalytic method enables easy access to various functionalized 2-aroylaromatic carboxylic acid derivatives in good isolated yields. Based on our mechanistic studies, a Pd(II)/Pd(IV) catalytic cycle that involves aroyl radical intermediate is proposed for the reaction.

Synthesis of Phenolic Compounds via Palladium Catalyzed C-H Functionalization of Arenes.

Phenol and its derivatives are extremely useful compounds in organic synthesis, medicinal chemistry and material sciences. The synthesis of phenols involving selective construction of the C-O bond at a C-H bond of arenes using transition-metal catalysis represents the most appealing strategy. Indeed, active research is currently going on for the synthesis of valuable phenolic compounds using a transition-metal-catalyzed C-H functionalization strategy.

Molecular Oxygen Mediated Radical Dicarbofunctionalization of Olefin with Aldehyde.

Herein we present a metal- and peroxide-free method for the synthesis of sterically hindered amides bearing an all-carbon quaternary stereogenic center at the α-position via a one-pot alkylation/aryl-migration/desulfonylation radical cascade. The novel process is developed employing readily available and inexpensive aldehyde as an alkyl radical precursor and O as the sole oxidant. The method features a broad substrate scope, operational simplicity, convenient reagents, and scalability.

Aerobic Radical-Cascade Alkylation/Cyclization of α,β-Unsaturated Amides: an Efficient Approach to Quaternary Oxindoles.

An efficient method for the aerobic radical-cascade alkylation/cyclization of α,β-unsaturated amides to afford functionalized oxindoles with a C3 quaternary stereocenter is described. The process is based on the generation of valuable alkyl radicals through sustainable aerobic C-H activation of aldehydes followed by decarbonylation using O2 as the sole oxidant. This method features a broad substrate scope, inexpensive alkyl radical precursors, and convenient reagents.