Photocatalytic Decarboxylative Coupling of Aliphatic N-hydroxyphthalimide Esters with Polyfluoroaryl Nucleophiles.

Polyfluoroarenes are an important class of compounds in medical and material chemistry. The synthesis of alkylated polyfluoroarenes remains challenging. Here we describe a decarboxylative coupling reaction of N-hydroxyphthalimide esters of aliphatic carboxylic acids with polyfluoroaryl zinc reagents (Zn-ArF ) via synergetic photoredox and copper catalysis. This method readily converts primary and secondary alkyl carboxylic acids into the corresponding polyfluoroaryl compounds, which could have a wide range of F-content (2F-5F) and variable F-substitution patterns on the aryl groups. Broad scope and good functional group compatibility were achieved, including on substrates derived from natural products and pharmaceuticals. Mechanistic study revealed that a [Cu-(ArF )2 ] species could be responsible for the transfer of polyfluoroaryl groups to the alkyl radicals.

Intermolecular oxidative amination of unactivated alkenes by dual photoredox and copper catalysis.

Oxidative amination of alkenes via amidyl radical addition is potentially an efficient method to generate allylic amines, which are versatile synthetic intermediates to bioactive compounds and organic materials. Here by combining photochemical generation of amidyl radicals with Cu-mediated ß-H elimination of alkyl radicals, we have developed an intermolecular oxidative amination of unactivated alkenes. The reaction relies on tandem photoredox and copper catalysis, and works for both terminal and internal alkenes. The radical nature of the reaction and the mild conditions lead to high functional group tolerance.

Formal Aza-Wacker Cyclization by Tandem Electrochemical Oxidation and Copper Catalysis.

In oxidative electrochemical organic synthesis, radical intermediates are often oxidized to cations on the way to final product formation. Herein, we describe an approach to transform electrochemically generated organic radical intermediates into neutral products by reaction with a metal catalyst. This approach combines electrochemical oxidation with Cu catalysis to effect formal aza-Wacker cyclization of internal alkenes. The Cu catalyst is essential for transforming secondary and primary alkyl radical intermediates into alkenes. A wide range of 5-membered N-heterocycles including oxazolidinone, imidazolidinone, thiazolidinone, pyrrolidinone, and isoindolinone can be prepared under mild conditions.

Identification of miRNA and genes involving in osteosarcoma by comprehensive analysis of microRNA and copy number variation data.

The aim of the present study was to understand the molecular mechanisms of osteosarcoma by comprehensive analysis of microRNA (miRNA/miR) and copy number variation (CNV) microarray data. Microarray data (GSE65071 and GSE33153) were downloaded from the Gene Expression Omnibus. In GSE65071, differentially expressed miRNAs between the osteosarcoma and control groups were calculated by the Limma package. Target genes of differentially expressed miRNAs were identified by the starBase database. For GSE33153, PennCNV software was used to perform the copy number variation (CNV) analysis. Overlapping of the genes in CNV regions and the target genes of differentially expressed miRNAs were used to construct miRNA-gene regulatory network using the starBase database. A total of 149 differentially expressed miRNAs, including 13 downregulated and 136 upregulated, were identified. In the GSE33153 dataset, 987 CNV regions involving in 3,635 genes were identified. In total, 761 overlapping genes in 987 CNV regions and in the genes in 7,313 miRNA-gene pairs were obtained. miRNAs (hsa-miR-27a-3p, hsa-miR-124-3p, hsa-miR-9-5p, hsa-miR-182-5p, hsa-miR-26a-5p) and the genes [Fibroblast growth factor receptor substrate 2 (FRS2), coronin 1C (CORO1C), forkhead box P1 (FOXP1), cytoplasmic polyadenylation element binding protein 4 (CPEB4) and glucocorticoid induced 1 (GLCCI1)] with the highest degrees of association with osteosarcoma development were identified. Hsa-miR-27a-3p, hsa-miR-9-5p, hsa-miR-182-5p, FRS2, CORO1C, FOXP1 and CPEB4 may be involved in osteosarcoma pathogenesis, and development.

MeOTf-Mediated Annulation of Alkylnitriles and Arylalkynes Leading to Polysubstituted NH-Pyrroles.

A metal-free multicomponent domino reaction for the highly regioselective synthesis of tetrasubstituted NH-pyrroles from readily available alkylnitriles, arylalkynes, and MeOTf has been developed. A variety of NH-pyrroles were obtained in moderate to good yields under mild conditions. In addition, the reactions using diarylalkynes with electron-rich aryl groups were found to afford isoquinolines.

Substrate-Controlled Transformation of Azobenzenes to Indazoles and Indoles via Rh(III)-Catalysis.

Rh(III)-catalyzed substrate-controlled transformation of azobenzenes to indazoles and 2-acyl (NH) indoles is achieved via C-H functionalization. Generally, good functional groups tolerance, satisfying yields, and excellent regio-selectivity are achieved in this reaction. Mechanistically, the reaction with acrylates undergoes ß-hydride elimination, while the reaction with vinyl ketones or acrylamides undergoes nucleophilic addition. Copper acetate was supposed to play different roles in the ß-hydride elimination to furnish indazoles and nucleophilic addition of C-Rh bond to deliver 2-acyl (NH) indoles.

I2-Mediated 2H-indazole synthesis via halogen-bond-assisted benzyl C-H functionalization.

I2-Mediated benzyl C-H functionalization has been developed for the synthesis of 2H-indazoles, which features high efficiency, simple conditions and no need for metals. Mechanistic experiments and DFT calculations have revealed halogen bond assistance and a radical chain process for this reaction. The azo group and the bound iodine cooperate in the hydrogen abstraction step, which circumvents the thermodynamic disfavor of direct hydrogen abstraction by a simple iodine radical.

Copper-Promoted Tandem Reaction of Azobenzenes with Allyl Bromides via N═N Bond Cleavage for the Regioselective Synthesis of Quinolines.

A copper-promoted tandem reaction of a variety of azobenzenes and allyl bromides via N═N bond cleavage to regioselectively construct quinoline derivatives has been developed. The azobenzenes act as not only construction units but also an oxidant for quinoline formation.