Palladium-Catalyzed Oxidative Carbonylation for the Synthesis of Polycyclic Aromatic Hydrocarbons (PAHs)

A direct and facile palladium-catalyzed C–H bond oxidative carbonylation reaction and oxidative cyclization for the synthesis of polycyclic aromatic hydrocarbons (PAHs) is reported herein. The intramolecular cyclocarbonylation, through C–H activation and C–C, C–O bond formations under mild conditions, proceeds smoothly with good functional group tolerance in high to excellent yields. The intramolecular palladium-catalyzed direct oxidative C–H bond functionalization for the C–O bond formation is also demonstrated, which provides an efficient approach for the construction of various PAHs

Cu(II)-Promoted Transformations of α-Thienylcarbinols into Spirothienooxindoles: Regioselective Halogenation of Dienyl Sulfethers Containing Electron-Rich Aryl Rings

Under the promotion of Cu­(II) salts, the α-thienylcarbinols with an <i>N</i>-phenyl carbonyl group at the other α-position are converted into three different ranges of spirothienooxindoles involving dearomatizing Friedel–Crafts reaction. In addition, the unprecedented regioselective CuX₂-mediated C–H functionalization/halogenation of dienyl sulfether containing electron-rich aryl rings is presented

Palladium-Catalyzed Oxidative O–H/N–H Carbonylation of Hydrazides: Access to Substituted 1,3,4-Oxadiazole-2(3<i>H</i>)‑ones

A novel palladium-catalyzed oxidative annulation reaction for the C–O, C–N bond formations is developed. The intramolecular cyclocarbonylation provides an efficient and direct approach for the construction of valuable 1,3,4-oxadiazole-2­(3<i>H</i>)-ones and their derivatives. The reaction also facilitated the convenient synthesis of BMS-191011, an opener of the cloned large-conductance Ca²⁺-activated potassium channel, providing an attractive method for medicinal chemistry

A Palladium-Catalyzed Carbonylative Acetylation of <i>N</i>‑Phenylpyridin-2-amine Using DMF and CO as the Acetyl Source

This study reports a carbonylative acetylation for the synthesis of N-phenyl-N-(pyridin-2-yl)acetamides using N,N-dimethylformamide (DMF) as a methyl source and CO as a carbonyl source. Interestingly, dimethyl sulfoxide (DMSO) can be also used as a methyl source when using only DMSO as the solvent. Mechanistic studies using DMSO-d6 revealed that the methyl group was derived from the methyl group of DMF instead of DMSO when using DMF and DMSO as a mixed solvent. These results indicated that DMF was a preferential methyl source

Carbonylation Access to Phthalimides Using Self-Sufficient Directing Group and Nucleophile

Herein we report a novel palladium-catalyzed oxidative carbonylation reaction for the synthesis of phthalimides with high atom- and step-economy. In our strategy, the imine and H₂O, which are generated <i>in situ</i> from the condensation of aldehyde and amine, serve as self-sufficient directing group and nucleophile, respectively. This method provides rapid access to phthalimides starting from readily available materials in a one-pot manner. Various phthalimide derivatives are constructed efficiently, including medicinally and biologically active phthalimide-containing compounds

Facile Synthesis of 3a,6a-Dihydro-furo[2,3-b]furans and Polysubstituted Furans Involving Dearomatization of Furan Ring via Electrocyclic Ring-Closure

A facile and atom-economic method for the synthesis of 3a,6a-dihydro-furo[2,3-b]furan derivatives and polysubstituted furans starting from furylcarbionls has been developed. This protocol involved a domino Claisen rearrangement/dearomatizing electrocyclic ring-closure/aromatizing electrocyclic ring-opening sequence

Transition Metal Free Intermolecular Direct Oxidative C–N Bond Formation to Polysubstituted Pyrimidines Using Molecular Oxygen as the Sole Oxidant

Various polysubstituted pyrimidines are smoothly formed via a base-promoted intermolecular oxidation C–N bond formation of allylic C­(sp³)–H and vinylic C­(sp²)–H of allyllic compounds with amidines using O₂ as the sole oxidant. This protocol features protecting group free nitrogen sources, good functional group tolerance, high atom economy, and environmental advantages

Electrochemical Oxidative Carbonylation of <i>N</i>H‑Sulfoximines

The electrochemical synthesis of N-aroylsulfoximines features the use of tetra-n-butylammonium iodide (TBAI) as the medium and a broad substrate scope, thus affording a wide range of N-aroylated sulfoximines in moderate to good yields. The advantages of this electrochemical strategy are augmented by mild reaction conditions that are external oxidant-free, ligand-free, and easy to scale up to gram scale. Both the control experiments and the mechanistic studies revealed that the whole electrochemical process proceeded through a palladium (II/IV/II) catalytic cycle

Base-Mediated Decomposition of Amide-Substituted Furfuryl Tosylhydrazones: Synthesis and Cytotoxic Activities of Enynyl-Ketoamides

Base-mediated decomposition of amide-substituted furfuryl tosylhydrazones afforded practical access to novel multifunctionalized enynyl-ketoamides. In addition, furfuryl tosylhydrazones with stable furan rings underwent an interesting tosyl-group migration to form sulfones, which have potential synthetic applications. Some of the obtained enynyl-ketoamides demonstrated good cytotoxicities against human tumor cell lines