Chiral induction in a novel self-assembled supramolecular system composed of α-cyclodextrin porous liquids, chiral silver nanoparticles and planar conjugated molecules

The newly developed porous liquids known as liquids with permanent microporosity, are of considerable application potential which still has many unknown areas. Herein, a supramolecular system composed of α-cyclodextrin porous...

Catalytic asymmetric Nakamura reaction by gold(I)/chiral N,Nʹ-dioxide-indium(III) or nickel(II) synergistic catalysis

Intermolecular addition of enols and enolates to unactivated alkynes was proved to be a simple and powerful method for carbon-carbon bond formation. Up to date, a catalytic asymmetric version of alkyne with 1,3-dicarbonyl compound has not been realized. Herein, we achieve the catalytic asymmetric intermolecular addition of 1,3-dicarbonyl compounds to unactivated 1-alkynes attributing to the synergistic activation of chiral N,N′-dioxide-indium(III) or nickel(II) Lewis acid and achiral gold(I) π-acid. A range of β-ketoamides, β-ketoesters and 1,3-diketones transform to the corresponding products with a tetra-substituted chiral center in good yields with good e.r. values. Besides, a possible catalytic cycle and a transition state model are proposed to illustrate the reaction process and the origin of chiral induction based on the experimental investigations.

Solid Phase Nitrosylation of Enantiomeric Cobalt(II) Complexes

Accompanied by a change in color from red to black, the enantiomorphic phases of the cobalt complexes of a chiral salen ligand (L2−, Co(L)·CS2, and Co(L) (L = LS,S or LR,R)) chemisorb NO (g) at atmospheric pressure and rt over hours for the CS2 solvated phase, and within seconds for the desolvated phase. NO is installed as an axial nitrosyl ligand. Aligned but unconnected voids in the CS2 desorbed Co(LR,R)·CS2 structure indicate conduits for the directional desorption of CS2 and reversible sorption of NO, which occur without loss of crystallinity. Vibrational circular dichroism (VCD) spectra have been recorded for both hands of LH2, Zn(L), Co(L)·CS2, Co(L), Co(NO)(L), and Co(NO)(L)·CS2, revealing significant differences between the solution-state and solid-state spectra. Chiral induction enables the detection of the νNO band in both condensed states, and surprisingly also the achiral lattice solvent (CS2 (νCS at 1514 cm−1)) in the solid-state VCD. Solution-state spectra of the paramagnetic Co(II) complex shows a nearly 10-fold enhancement and more extensive inversion of polarity of the vibrations of dominant VCD bands compared to the spectra of the diamagnetic compounds. This enhancement is less pronounced when there are fewer polarity inversions in the solid state VCD spectra.

The Use of cinchona Alkaloid Derivatives as Chiral Ligands and Organocatalysts in Asymmetric Catalysis

: Cinchona alkaloids are natural products extracted from cinchona plants, which contain quinine, quinidine, cinchonine, and cinchonidine. During the past 30 years, due to their attractive structural properties, these compounds have been used as chiral skeletons and organocatalysts in asymmetric organic synthesis. In this review, we summarize the applications of cinchona alkaloids derivatives in asymmetric catalysis recently developed by our group, including oxidation, reduction, and C-C bonds formation. These studies solved some of the problems with the various asymmetric reactions discussed, while also enriching alkaloids chemistry, providing new ideas for the design and synthesis of chiral catalysts, and providing abundant experimental data for the chiral induction process.

Enantioselective Hydroalkylation of α,β-Unsaturated Amides through Reversed syn-Hydrometallation of NiH

Enantioselective synthesis of a wide range of structurally diverse <a>β</a>-chiral amides has been achieved through nickel-catalyzed regio-reversed hydroalkylation of α,β-unsaturated amides with alkyl iodides in the presence of a hydrosilane. Different from the classical homolysis/enantioconvergent recombination process of Ni(III) intermediates as the enantio-determining step, chiral induction in this reductive hydroalkylation was achieved through an enantiodifferentiating regio-reversed <i>syn</i>-hydrometallation process of α,β-unsaturated amides.