Synthesis of 2,3-Difunctionalized Benzofuran Derivatives through Palladium-Catalyzed Double Isocyanide Insertion Reaction

A novel palladium-catalyzed tandem cyclization of 1-(allyloxy)-2-ethynylbenzene derivatives with isocyanides in the presence of water has been developed. The key intermediates, benzofuran-3-α-carbonyl aldehydes, were obtained through a simple acid hydrolysis process and could serve as precursors for structurally diverse 2,3-difunctionalized benzofuran derivatives such as important 2-benzofurylquinoxalines, benzofuran-3-α-ketoesters and benzofuryl ynediones. This transformation features convenient operation, simple and commercially available starting materials, broad functional-group compatibility, and moderate to good reaction yields

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

Oxidative C–H/N–H Carbonylation of Benzamide by Nickel Catalysis with CO as the Carbonyl Source

An efficient and direct carbonylation of aminoquinoline benzamides has been developed using abundant and inexpensive Ni­(OAc)2·4H2O as the catalyst and carbon monoxide as a cost-efficient C1 building block. This process features good functional-group tolerance and can be conducted on gram scale. The directing group can be easily removed under mild conditions

Palladium-Catalyzed Multistep Tandem Carbonylation/N-Dealkylation/Carbonylation Reaction: Access to Isatoic Anhydrides

A novel and efficient synthesis of isatoic anhydride derivatives was developed via palladium-catalyzed multistep tandem carbonylation/N-dealkylation/carbonylation reaction with alkyl as the leaving group and tertiary anilines as nitrogen nucleophiles. This approach features good functional group compatibility and readily available starting materials. Furthermore, it provided a convenient approach for the synthesis of biologically and medicinally useful evodiamine

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

Electrochemical N‑Acylation of Sulfoximine with Hydroxamic Acid

Despite the widespread applications of sulfoximines, green and efficient access to functionalized sulfoximines remains a challenge. By employing an electrochemical strategy, we describe an approach for the construction of N-aroylsulfoximines, which features a broad substrate scope, mild reaction conditions, safety on a gram scale, and no need for an external oxidant and transition metal catalysts

Copper-Catalyzed Sulfonylation Reaction of NH-Sulfoximines with Aryldiazonium Tetrafluoroborates and Sulfur Dioxide: Formation of <i>N</i>‑Sulfonyl Sulfoximines

An efficient and practical SO2 insertion protocol of NH-sulfoximines with aryldiazonium tetrafluoroborates and DABSO toward N-sulfonyl sulfoximines has been developed under mildly basic conditions. This transformation features easy operation, readily available substrates, and mild conditions. A tentative mechanism is proposed, which indicates that the aryldiazonium tetrafluoroborates would be radical donors under standard reaction conditions. The aryl radical produced in situ from diazonium salts would be trapped by SO2 to generate an arylsulfonyl radical and then undergo further transformation to generate the final N-sulfonyl sulfoximines

Copper-Catalyzed Divergent C–H Functionalization Reaction of Quinoxalin-2(1<i>H</i>)‑ones and Alkynes Controlled by N1-Substituents for the Synthesis of (<i>Z</i>)‑Enaminones and Furo[2,3‑<i>b</i>]quinoxalines

With control by N1-substituents, the switchable divergent C–H functionalization reaction of quinoxalin-2­(1H)-ones is achieved for the synthesis of (Z)-enaminones and furo­[2,3-b]­quinoxalines using the combination of a copper catalyst and an oxidant. This new protocol features mild reaction conditions, readily available materials, and a broad substrate scope. Gram-scale and mechanistic studies were also investigated. Furthermore, the desired products exhibited excellent antitumor activity against A549, HepG-2, MCF-7, and HeLa cells, which were tested by MTT assay

Selective Electrochemical Halogenation of Functionalized Quinolone

This work describes an effective C3–H halogenation of quinoline-4(1H)-ones under electrochemical conditions, in which potassium halides serve as both halogenating agents and electrolytes. The protocol provides expedient access to different halogenated quinoline-4(1H)-ones with unique regioselectivity, broad substrate scope, and gram-scale synthesis employing convenient, environmentally friendly electrolysis, in an undivided cell. Mechanism studies have shown that halogen radicals can promote the activation of N–H bonds in quinolones