Construction of Heterobiaryl Skeletons through Pd-Catalyzed Cross-Coupling of Nitroarenes and Heterocyclic Arylborononate Esters with a Sterically Demanding NHC Ligand

The palladium-catalyzed Suzuki–Miyaura cross-couplings of nitroarenes and heteroarylboronate esters has been developed. A number of heterobiaryl compounds containing pyridine, pyrimidine, quinoline, furan, thiophene, and pyrazole were prepared using [Pd(cinnamyl)Cl]2/2-aryl-5-(2,4,6-triisopropylphenyl)-2,3-imidazolylidene[1,5-a]pyridines as the catalysts in good to excellent yields. The synthetic practicality of this approach is demonstrated through the synthesis of druglike molecules

Palladium-Catalyzed Sequential Heteroarylation/Acylation Reactions of Iodobenzenes: Synthesis of Functionalized Benzo[<i>d</i>]oxazoles

We report an efficient palladium-catalyzed approach to the synthesis of benzoxazole derivatives via sequential heteroarylation/acylation reaction of iodobenzenes. Three readily available starting materials, iodobenzenes, anhydrides, and benzoxazoles, were smoothly coupled to form new C–C bonds at the <i>ortho</i> and <i>ipso</i> positions of the iodobenzenes to afford 2-heteroaryl-3-acylbenzene derivatives in good yields

Efficient Approach to Mesoionic Triazolo[5,1‑<i>a</i>]isoquinolium through Rhodium-Catalyzed Annulation of Triazoles and Internal Alkynes

Rhodium-catalyzed annulation reactions between triazoles and internal alkynes, leading to various mesoionic isoquinoliums, are described. The reaction involves sequential triazole-directed C–H activation and C–C, C–N, and C–O bond formation processes in a one-pot manner. The starting materials and catalysts are easily available. The reaction offers a facile and practical approach to mesoionic isoquinolium derivatives

Copper(I)-Catalyzed N–O Bond Formation through Vinyl Nitrene Mediated Pathway under Mild Conditions

Copper­(I)-catalyzed N–O bond formation reactions through vinyl nitrene-mediated pathway were described. The reactions of <i>N</i>-alkoxylbenzamides and 2<i>H</i>-azirines afforded α-amino oxime ethers in good to excellent yields at room temperature, which involved the cleavage of C–N and N–O bonds and the construction of new N–O and C–N bonds. It offers an efficient, regio- and stereoselective synthetic route for α-amino oxime ethers

Pd-Catalyzed Intramolecular Aerobic Oxidative C–H Amination of 2‑Aryl-3-(arylamino)­quinazolinones: Synthesis of Fluorescent Indazolo­[3,2‑<i>b</i>]­quinazolinones

A palladium-catalyzed intramolecular aerobic oxidative C–H amination of 2-aryl-3-(arylamino)­quinazolinones has been developed, providing a variety of substituted indazolo­[3,2-<i>b</i>]­quinazolinone derivatives in moderate to excellent yields. Preliminary mechanistic studies suggested that a palladacycle dimer could be the key intermediate, which underwent a cascade “rollover” cyclometalation and C–H amination sequence. Furthermore, the potential utility of these products has been demonstrated as a new class of blue fluorophores for fluorescent materials

Pd-Catalyzed Intramolecular Aerobic Oxidative C–H Amination of 2‑Aryl-3-(arylamino)­quinazolinones: Synthesis of Fluorescent Indazolo­[3,2‑<i>b</i>]­quinazolinones

A palladium-catalyzed intramolecular aerobic oxidative C–H amination of 2-aryl-3-(arylamino)­quinazolinones has been developed, providing a variety of substituted indazolo­[3,2-<i>b</i>]­quinazolinone derivatives in moderate to excellent yields. Preliminary mechanistic studies suggested that a palladacycle dimer could be the key intermediate, which underwent a cascade “rollover” cyclometalation and C–H amination sequence. Furthermore, the potential utility of these products has been demonstrated as a new class of blue fluorophores for fluorescent materials

Copper(I)-Catalyzed N–O Bond Formation through Vinyl Nitrene Mediated Pathway under Mild Conditions

Copper­(I)-catalyzed N–O bond formation reactions through vinyl nitrene-mediated pathway were described. The reactions of <i>N</i>-alkoxylbenzamides and 2<i>H</i>-azirines afforded α-amino oxime ethers in good to excellent yields at room temperature, which involved the cleavage of C–N and N–O bonds and the construction of new N–O and C–N bonds. It offers an efficient, regio- and stereoselective synthetic route for α-amino oxime ethers

Copper(I)-Catalyzed N–O Bond Formation through Vinyl Nitrene Mediated Pathway under Mild Conditions

Copper­(I)-catalyzed N–O bond formation reactions through vinyl nitrene-mediated pathway were described. The reactions of <i>N</i>-alkoxylbenzamides and 2<i>H</i>-azirines afforded α-amino oxime ethers in good to excellent yields at room temperature, which involved the cleavage of C–N and N–O bonds and the construction of new N–O and C–N bonds. It offers an efficient, regio- and stereoselective synthetic route for α-amino oxime ethers

Synergistic Photo-Copper-Catalyzed Hydroxylation of (Hetero)aryl Halides with Molecular Oxygen

Photoredox-mediated copper-catalyzed hydroxylation of (hetero)­aryl halides (including chlorides, bromides, and iodides) with O₂ at room temperature has been developed. Preliminary mechanistic studies indicate no arylcopper intermediate and that aryl radicals are involved in this procedure. ¹⁸O-labeling experiments confirm the hydroxyl oxygen atom originated from molecular oxygen

Unexpected Copper-Catalyzed Cascade Synthesis of Quinazoline Derivatives

The first example of a copper-catalyzed cascade reaction of (2-aminophenyl)­methanols with aldehydes using the combination of cerium nitrate hexahydrate and ammonium chloride has been developed, leading to a wide range of 2-substituted quinazolines in moderate to excellent yields. The efficiency of this transformation was demonstrated by compatibility with a wide range of functional groups. Thus, the method represents a convenient and practical strategy for synthesis of 2-substituted quinazoline derivatives