Chiral bisoxazoline ligands containing naphthyridine, pyridazine, pyrazole, and phenol bridging units were prepared and shown to form bimetallic complexes with various metal salts. X-ray crystal structures of bis-nickel naphthyridine-bridged, bis-zinc pyridazine-bridged, and bis-nickel as well as bis-palladium pyrazole-bridged complexes were obtained.
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http://dx.doi.org/10.3762/bjoc.14.175 | DOI Listing |
Precis Chem
December 2024
Department of Molecular and Macromolecular Chemistry, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan.
Dual control of the molecular weight and tacticity in proton transfer anionic polymerization (PTAP) of methyl methacrylate (MMA) was investigated by using various ligands in the presence of a bulky potassium base catalyst and an organic compound with a weakly acidic C-H bond as dormant species in toluene at 0 °C. The tacticity of the resulting poly(MMA) (PMMA) produced without ligands was nearly atactic (// = 22/54/24). However, the use of 18-crown-6 as a ligand afforded predominantly syndiotactic PMMA ( ≈ 58%), whereas the use of chiral bis(oxazoline) ligands gave slightly isotactic-rich PMMA ( ≈ 32%).
View Article and Find Full Text PDFJ Am Chem Soc
December 2024
State Key Laboratory of Chemical Oncogenomics, Institute of Biopharmaceutics and Health Engineering, Tsinghua Shenzhen International Graduate School, Shenzhen 518055, China.
The high percentage of sp-hybridized carbons and the presence of chiral carbon centers could contribute to increased molecular complexity, enhancing the likelihood of clinical success of drug candidates. Three-dimensional (3D) bridged motifs have recently garnered significant interest in medicinal chemistry. Bicyclo[2.
View Article and Find Full Text PDFJ Am Chem Soc
November 2024
Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, Shanghai Frontiers Science Center of Molecule Intelligent Syntheses, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200062, China.
The direct use of readily available aldehydes as acyl radical precursors has facilitated diverse three-component acylative difunctionalization reactions of alkenes, offering a powerful route to synthesize β-branched ketones. However, asymmetric three-component acylative difunctionalization of alkenes with aldehydes still remains elusive. Here we report a copper-catalyzed asymmetric three-component radical acylarylation of vinylarenes with aldehydes and aryl boronic acids.
View Article and Find Full Text PDFJ Am Chem Soc
November 2024
Department of Chemistry, University of California Riverside, Riverside, California 92521, United States.
This manuscript details the development of an asymmetric variant for the Ni-photoredox α-arylation of tetrahydrofuran (THF), which was originally reported in a racemic fashion by Doyle and Molander. Leveraging the enantioselectivity data that we obtained, a complex mechanistic scenario different from those originally proposed is uncovered. Specifically, an unexpected dependence of the product enantiomeric ratio was observed on both the halide identity (aryl chloride vs bromide substrates) and the Ni source.
View Article and Find Full Text PDFNat Chem
November 2024
State Key Laboratory of Synthetic Chemistry, Department of Chemistry, The University of Hong Kong, Hong Kong, China.
The high nitrogen content and diverse reactivity of malononitrile are widely harnessed to access nitrogen-rich fine chemicals. Although the facile substitutions of malononitrile can give structurally diverse quaternary carbons, their access to enantioenriched molecules, particularly chiral amines that are prevalent in bioactive compounds, remains rare. Here we report a cobalt-catalysed desymmetric reduction of disubstituted malononitriles to give highly functionalized β-quaternary amines.
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