Robust bifunctional aluminium-salen catalysts for the preparation of cyclic carbonates from carbon dioxide and epoxides

Abstract Two new one-component aluminium-based catalysts for the reaction between epoxides and carbon dioxide have been prepared. The catalysts are composed of aluminium-salen chloride complexes with trialkylammonium groups directly attached to the aromatic rings of the salen ligand. With terminal epoxides, the catalysts induced the formation of cyclic carbonates under mild reaction conditions (25-35 °C; 1-10 bar carbon dioxide pressure). However, with cyclohexene oxide under the same reaction conditions, the same catalysts induced the formation of polycarbonate. The catalysts could be recovered from the reaction mixture and reused. 161

Robust bifunctional aluminium–salen catalysts for the preparation of cyclic carbonates from carbon dioxide and epoxides

Two new one-component aluminium-based catalysts for the reaction between epoxides and carbon dioxide have been prepared. The catalysts are composed of aluminium–salen chloride complexes with trialkylammonium groups directly attached to the aromatic rings of the salen ligand. With terminal epoxides, the catalysts induced the formation of cyclic carbonates under mild reaction conditions (25–35 °C; 1–10 bar carbon dioxide pressure). However, with cyclohexene oxide under the same reaction conditions, the same catalysts induced the formation of polycarbonate. The catalysts could be recovered from the reaction mixture and reused

CCDC 927098: Experimental Crystal Structure Determination

Related Article: Yuri N. Belokon, Victor I. Maleev, Michael North, Vladimir A. Larionov, Tat’yana F. Savel’yeva, Aike Nijland, and Yuliya V. Nelyubina|2013|ACS Catalysis|3|1951|doi:10.1021/cs400409d,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

CCDC 927099: Experimental Crystal Structure Determination

Related Article: Yuri N. Belokon, Victor I. Maleev, Michael North, Vladimir A. Larionov, Tat’yana F. Savel’yeva, Aike Nijland, and Yuliya V. Nelyubina|2013|ACS Catalysis|3|1951|doi:10.1021/cs400409d,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Expanding the Family of Octahedral Chiral-at-Metal Cobalt(III) Catalysts by Introducing Tertiary Amine Moiety into the Ligand

Chiral metal-templated complexes are attractive catalysts for organic synthetic transformations. Herein, we introduce a novel chiral cobalt(III)-templated complex based on chiral trans-3,4-diamino-1-benzylpyrrolidine and 3,5-di-tert-butyl-salicylaldehyde which features both hydrogen bond donor and Brønsted base functionalities. The obtained complexes were fully characterized by 1H, 13C NMR, IR-, UV-vis, CD-spectroscopy and by a single X-ray diffraction analysis. It was shown that chlorine anion is connected with amino groups of the complex via a hydrogen bonding. DFT calculations of charges and molecular electrostatic potential of the cobalt(III) complex showed that the basicity of the complex is certainly diminished as compared with the routine tertiary amines but the acidity of the conjugated acid of the complex should be increased. Thus, the catalytic potential of the complex may be much greater as a chiral acid than a chiral base. We believe that this work opens a new way in chiral bifunctional catalyst design

Atom- and Step-Economical Preparation of Reduced Knoevenagel Adducts Using CO as a Deoxygenative Agent

A highly efficient one-step Rh-catalyzed preparation of reduced Knoevenagel adducts of various aldehydes and ketones with active methylene compounds has been developed. The protocol does not require an external hydrogen source and employs carbon monoxide as a deoxygenative agent. The use of malonic acid or cyanoacetamide enabled efficient formal deoxygenative addition of methyl acetate or acetonitrile to aldehydes. The developed methodology was applied to the synthesis of the precursors of biomedically important compounds

Ruthenium-Catalyzed Reductive Amination without an External Hydrogen Source

A ruthenium-catalyzed reductive amination without an external hydrogen source has been developed using carbon monoxide as the reductant and ruthenium­(III) chloride (0.008–2 mol %) as the catalyst. The method was applied to the synthesis of antianxiety agent ladasten

Self-Assembled Ionic Composites of Negatively Charged Zn(salen) Complexes and Triphenylmethane Derived Polycations as Recyclable Catalysts for the Addition of Carbon Dioxide to Epoxides

The design and synthesis of a novel type of self-assembled ionic composite composed of negatively charged Zn(salen) complexes and triphenylmethane derived polycations is reported. These composites were applied as easily recyclable catalysts for carbon dioxide addition to epoxides. The composites functioned as bifunctional catalysts which could be easily separated and recycled by precipitation from the reaction mixture upon addition of tetrachloromethane. The same batch of the catalyst could be employed for, at least, five runs with its catalytic properties improving as it was reused. A fully heterogeneous system was also prepared by cross-linking leuco dye with para-dibromoxylene and adding to it calculated amounts of Zn(salen) complex. The heterogeneous system was catalytically competent in the reaction between styrene oxide and carbon dioxide and its activity also increased on its reuse

Chiral Octahedral Complexes of Co^III As a Family of Asymmetric Catalysts Operating under Phase Transfer Conditions

Stereochemically inert and positively charged chiral complexes of Co^III prepared from Schiff bases derived from chiral diamines and salicylaldehydes were shown to be efficient catalysts of the asymmetric phase transfer benchmark reaction of alkylation of O’Donnell’s substrate with alkyl halides. The enantiomeric purities of the reaction products were up to 92%

Chiral Octahedral Complexes of Co^III As a Family of Asymmetric Catalysts Operating under Phase Transfer Conditions

Stereochemically inert and positively charged chiral complexes of Co^III prepared from Schiff bases derived from chiral diamines and salicylaldehydes were shown to be efficient catalysts of the asymmetric phase transfer benchmark reaction of alkylation of O’Donnell’s substrate with alkyl halides. The enantiomeric purities of the reaction products were up to 92%