Metal-Free Oxidative Spirocyclization of Hydroxymethylacrylamide with 1,3-Dicarbonyl Compounds: A New Route to Spirooxindoles

A metal-free oxidative spirocyclization of hydroxymethylacrylamide with 1,3-dicarbonyl compounds is described. The reaction proceeds through tandem dual C–H functionalization and intramolecular dehydration, in which two new C–C bonds and one C–O bond were formed. This method affords a novel and straightforward access to various spirooxindoles under mild conditions

Palladium-Catalyzed Alkylarylation of Acrylamides with Unactivated Alkyl Halides

An efficient palladium-catalyzed alkylarylation of acrylamides with unactivated alkyl halides has been developed. This method is highlighted by its broad substrate scope and excellent functional group tolerance. In addition to alkyl halides, fluoroalkyl halides and benzyl bromides also participated well in this transformation. A detailed mechanistic investigation suggests that a radical pathway is probably involved in the cyclization process

Alkynylation of Tertiary Cycloalkanols via Radical C–C Bond Cleavage: A Route to Distal Alkynylated Ketones

An efficient Na₂S₂O₈-promoted radical coupling of tertiary cycloalkanols with alkynyl hypervalent iodide reagents via C–C bond cleavage was developed. This tandem ring-opening/alkynylation procedure showed some advantages, including mild conditions and wide substrate scope, thus providing a simple synthetic method for β-, γ- and δ-alkynylated ketones

Decarboxylative Alkynylation of α‑Keto Acids and Oxamic Acids in Aqueous Media

A mild K₂S₂O₈ promoted decarboxylative alkynylation of α-keto acids and oxamic acids has been developed. This process features mild reaction conditions, a broad substrate scope, and good functional-group tolerance, therefore providing a new and efficient access to a wide range of ynones and propiolamides. Furthermore, this radical process could also be successfully applied to alkynylation of the C_sp²–H bond in DMF with hypervalent alkynyl iodide reagents

Direct C–H Cyanoalkylation of Heteroaromatic <i>N</i>‑Oxides and Quinones via C–C Bond Cleavage of Cyclobutanone Oximes

A direct C–H cyanoalkylation of heteroaromatic <i>N</i>-oxides and quinones with cyclobutanone oximes is reported. This redox-neutral, operationally simple cyanoalkylation reaction is successfully amenable to a wide range of heteroaromatic <i>N</i>-oxides, quinones, and cyclobutanone oximes. A novel catalytic system consisting of a nickel source proved crucial for cleavage of the C–C bond of cyclobutanone oximes and for selective C–C bond formation over β-hydride elimination. Mechanistic studies suggest that a radical intermediate might be involved in this transformation

Redox-Neutral Cyanoalkylation/Cyclization of Olefinic 1,3‑Dicarbonyls with Cycloketone Oxime Esters: Access to Cyanoalkylated Dihydrofurans

Metal-catalyzed cyanoalkylation/cyclization of olefinic 1,3-dicarbonyls with cycloketone oxime esters has been developed under redox-neutral conditions. This protocol provided a straightforward approach to diverse cyanoalkylated 2,3-dihydrofurans via a tandem ring-opening/addition/cyclization process

Iron-Catalyzed Decarboxylative Olefination of Cycloketone Oxime Esters with α,β-Unsaturated Carboxylic Acids via C–C Bond Cleavage

An iron-catalyzed redox-neutral, decarboxylative olefination of cycloketone oxime esters with α,β-unsaturated carboxylic acids has been developed. This reaction involves an iminyl radical mediated C–C bond cleavage/radical addition/decarboxylation cascade. This protocol is highlighted by its low-cost catalytic system and readily accessible starting materials, as well as broad substrate scope, thus providing facile access to structurally diverse cyano-containing alkenes

Metal-Free, Visible-Light-Promoted Decarboxylative Radical Cyclization of Vinyl Azides with <i>N</i>‑Acyloxyphthalimides

A visible-light-mediated decarboxylative cyclization of <i>N</i>-acyloxylphthalimides with vinyl azides has been developed under metal-free conditions. This protocol features mild conditions, a broad substrate scope, and an excellent functional group tolerance, thus providing a facile and efficient access to substituted phenanthridines. Control experiments revealed that the reaction proceeded via a radical process

Nickel-Catalyzed Modular Four-Component 1,4-Alkylcarbonylation of 1,3-Enynes to Tetra-Substituted CF₃–Allenyl Ketones

The modular four-component carbonylation of unsaturated hydrocarbons represents an elegant strategy for the one-pot synthesis of complex carbonyl compounds. However, this strategy is currently focused on the 1,2-difunctionalization of olefins or alkynes, and the 1,4-alkylcarbonylation of 1,3-enynes remains unexplored. In this study, we report a Ni-catalyzed 1,4-alkylcarbonylation of CF3-containing 1,3-enynes under 1 atm of CO, which affords the tetra-substituted CF3-allenyl ketones with good yields and selectivity. This protocol features mild conditions, broad substrate scope, and acceptable functional group compatibility. Control experiments revealed that the reactivity of oxime esters (regulated by leaving groups) and polarity matching are crucial for the success of this four-component cascade. Preliminary mechanistic studies suggest that the acyl nickel complex is a key intermediate in this transformation