Access to Unsymmetric -Terphenyl Derivatives via Ligand-Promoted Pd-Catalyzed Remote -C-H Arylation.

Achieving high -selective C-H arylation of electron-poor benzoic acid derivatives is still a daunting challenge, which could be an efficient protocol to construct unsymmetrical 1,3-disubstituted benzene derivatives. Herein, we report the ligand-promoted high -selective C-H arylation of benzoic acid derivatives. A wide range of unsymmetric and unfunctionalized 1,3-disubstituted benzene derivatives were obtained.

Ligand-Accelerated Pd-Catalyzed C(sp)-H and C(sp)-H Arylation under the Catalytic System.

It is universally acknowledged that ligands can improve the reaction activity to simplify the reaction operating conditions and enrich the applicability of the reaction. Therefore, we developed -octylglycine ligand-accelerated Pd-catalyzed -arylation of benzoic acids under mild conditions with just 6 h; moreover, this -octylglycine ligand was successfully implemented to carboxyl-directed Pd-catalyzed β-C(sp)-H arylation and arylation of phenylacetic acids under mild conditions.

Ligand Promoted Pd-Catalyzed High -Selective C-H Olefination.

Achieving high -selective C-H functionalized products of benzoic acid derivatives using a designed template is still a daunting challenge because the carbonyl group also could coordinate with metal to activate the -C-H bond. Herein, we report the ligand promoted high -selective C-H olefination of benzoic acid derivatives; we screened a series of ligands increasing the ratio of :others from 62:38 to 96:4. This work may find application in the construction of -substituted benzoic acid derivatives.

A Cheap and Efficient Oxidant (-Bu)NNO-Enabled C(sp)- and C(sp)-H Olefination at Room Temperature.

To further promote the widely practical application of C-H activation, developing green and mild reaction conditions has invariably been the objective of researchers, especially when it comes to remote C-H activation reactions. Herein, we report a new cheap and powerful (-Bu)NNO oxidant. This oxidant is efficient and universal for Pd(II)-catalyzed sp and sp C-H olefination and allows the reaction to be carried out at room temperature.

Cobalt(III)-catalyzed weakly coordinating arylurea-directed regioselective mono-olefination.

Here, we developed an air-stable, earth-abundant cobalt(III)-catalyzed regioselective mono-olefination of arenes directed by urea under mild conditions through a cross-dehydrogenative coupling (CDC) process. Under the optimized conditions, a high regioselectivity of mono-olefination was achieved with various electron-rich and electron-deficient arenes, which afforded -alkenylated products (with yields of up to 90%). In contrast to the conditions used for noble-metal-catalyzed olefination directed by weakly coordinating groups, our reaction was operated under mild conditions, including mild temperature (40 °C) and non-metallic oxidant.

Enhancing the Catalytic Performance of Candida antarctica Lipase B by Chemical Modification With Alkylated Betaine Ionic Liquids.

Various betaine ionic liquids composed of different chain lengths and different anions were designed and synthesized to modify lipase B (CALB). The results showed that the catalytic activity of all modified lipases improved under different temperature and pH conditions, while also exhibiting enhanced thermostability and tolerance to organic solvents. With an increase in ionic liquid chain length, the modification effect was greater.

Chemical modification for improving catalytic performance of lipase B from Candida antarctica with hydrophobic proline ionic liquid.

In this study, a series of proline ionic liquids with different lengths of hydrophobic alkyl on the side chain were used to modify the Candida Antarctic lipase B (CALB). The catalytic activity, thermal stability and tolerance to methanol and DMSO of the modified enzyme were all improved simultaneously. The optimum temperature changed from 55 to 60 ℃.

Rh(III)-Catalyzed C(sp)-H Acetoxylation of 8-Methylquinolines.

A mild and efficient Rh(III)-catalyzed aliphatic C-H acetoxylation directed by quinolines has been developed with widespread functional groups, including various halogens, which usually can provide precursors for further organic synthesis but easily results in selectivity issues in the Pd- and Ni-catalyzed reaction. Interestingly, AcO plays an essential role in promoting the transformation.

Ligand-Promoted Rh -Catalyzed Thiolation of Benzamides with a Broad Disulfide Scope.

A ligand-promoted Rh -catalyzed C(sp )-H activation/thiolation of benzamides has been developed. Using bidentate mono-N-protected amino acid ligands led to the first example of Rh -catalyzed aryl thiolation reactions directed by weakly coordinating directing amide groups. The reaction tolerates a broad range of amides and disulfide reagents.

Rh(III)-Catalyzed meta-C-H Alkenylation with Alkynes.

Rh(III)-catalyzed meta-C-H functionalization reactions are still rare. Herein, we report the first example of Rh(III)-catalyzed meta-C-H alkenylation with disubstituted alkynes directed by a U-shaped nitrile template. Exclusive regio-selectivity has been achieved using unsymmetrical aryl and alkyl-disubstituted alkynes to afford synthetically valuable trisubstituted olefins.

Porous Metal-Organic Frameworks with Chelating Multiamine Sites for Selective Adsorption and Chemical Conversion of Carbon Dioxide.

A combination of carbon dioxide (CO) capture and chemical fixation in a one-step process is attractive for chemists and environmentalists. In this work, by incorporating chelating multiamine sites to enhance the binding affinity toward CO, two novel metal-organic frameworks (MOFs) [Zn(L)(2,6-NDC)(HO)]·1.5DMF·2HO (1) and [Cd(L)(2,6-NDC)]·1.

Rhodium-Catalyzed Direct Ortho C-H Arylation Using Ketone as Directing Group with Boron Reagent.

A general method for selective ortho C-H arylation of ketone, with boron reagent enabled by rhodium complexes with excellent yields, is developed. The transformation is characterized by the use of air-stable Rh catalyst, high monoarylation selectivity, and excellent yields of most of the substrates.

Ligand-Promoted Rhodium(III)-Catalyzed ortho-C-H Amination with Free Amines.

Ligand development for rhodium(III)-catalyzed C-H activation reactions has largely been limited to cyclopentadienyl (Cp) based scaffolds. 2-Methylquinoline has now been identified as a feasible ligand that can coordinate to the metal center of Cp*RhCl to accelerate the cleavage of the C-H bond of N-pentafluorophenylbenzamides, providing a new structural lead for ligand design. The compatibility of this reaction with secondary free amines and anilines also overcomes the limitations of palladium(II)-catalyzed C-H amination reactions.

Rh(III)-Catalyzed meta-C-H Olefination Directed by a Nitrile Template.

A range of Rh(III)-catalyzed ortho-C-H functionalizations have been developed; however, extension of this reactivity to remote C-H functionalizations through large-ring rhodacyclic intermediates has yet to be demonstrated. Herein we report the first example of the use of a U-shaped nitrile template to direct Rh(III)-catalyzed remote meta-C-H activation via a postulated 12-membered macrocyclic intermediate. Because the ligands used for Rh(III) catalysts are significantly different from those of Pd(II) catalysts, this offers new opportunities for future development of ligand-promoted meta-C-H activation reactions.

Synthesis and antitumor activity of formononetin nitrogen mustard derivatives.

A series of formononetin nitrogen mustard derivatives were synthesized and evaluated in vitro for their cytotoxicity against five cancer cell lines (SH-SY5Y, HCT-116, DU-145, Hela and SGC-7901). The pharmacological results showed that many of the new derivatives displayed more potent cytotoxicity than alkeran. Furthermore, compounds 6d and 6n could induce cell cycle arrest at G2/M phase and cell apoptosis.

Synthesis and antitumor activity of liquiritigenin thiosemicarbazone derivatives.

In an attempt to develop potent and selective antitumor agents, a series of liquiritigenin thiosemicarbazone derivatives were designed and synthesized. The cytotoxicities of these compounds were evaluated in vitro against K562, DU-145, SGC-7901, HCT-116 and Hela cell lines. The pharmacological results showed that most of the prepared compounds displayed excellent selective cytotoxicity toward K562 and DU-145 cells.