The catalytic synthesis of cyclic carbonates via the cycloaddition of CO2 to epoxides is a standard methodology for CO2 fixation.For this purpose,chiral basket-handle porphyrin-Co complexes were devised,prepared,and f...The catalytic synthesis of cyclic carbonates via the cycloaddition of CO2 to epoxides is a standard methodology for CO2 fixation.For this purpose,chiral basket-handle porphyrin-Co complexes were devised,prepared,and fully characterized by nuclear magnetic resonance,mass spectrometry,Fourier transform infrared spectroscopy,ultraviolet-visible spectroscopy,and specific rotation.The proposed metalloporphyrin catalysts were synthesized with either 1,1'-bi-2-naphthol or L-phenylalanine,which have different chirality,and then applied to the coupling of propylene oxide and CO2 for generating chiral cyclic carbonates with good enantioselectivity under extremely mild conditions in the presence of tetrabutyl ammonium chloride as a co-catalyst.The good enantioselectivity in the cycloaddition reaction is attributed to a synergistic interplay between the chiral porphyrin catalysts and the substrate.The mechanism and enantioselectivity of the asymmetric cycloaddition reaction is discussed.展开更多
The dynamic transformations of conformations and aromatic properties of [32]octaphyrins（1.0.1.0.1.0.1.0） through rotating the pyrrolic ring of the macrocycles are demonstrated by theoretical simulations in CH2Cl2 so...The dynamic transformations of conformations and aromatic properties of [32]octaphyrins（1.0.1.0.1.0.1.0） through rotating the pyrrolic ring of the macrocycles are demonstrated by theoretical simulations in CH2Cl2 solution. Facile multistep isomeriza- tions involving antiaromatic-Htickel and aromatic-Mobius topologies were also predicted by density functional theory （DFT）. The understanding of changes in topologies and aromaticities of free-base expanded porphrins may provide useful information to build new macrocycles with unique properties.展开更多
文摘The catalytic synthesis of cyclic carbonates via the cycloaddition of CO2 to epoxides is a standard methodology for CO2 fixation.For this purpose,chiral basket-handle porphyrin-Co complexes were devised,prepared,and fully characterized by nuclear magnetic resonance,mass spectrometry,Fourier transform infrared spectroscopy,ultraviolet-visible spectroscopy,and specific rotation.The proposed metalloporphyrin catalysts were synthesized with either 1,1'-bi-2-naphthol or L-phenylalanine,which have different chirality,and then applied to the coupling of propylene oxide and CO2 for generating chiral cyclic carbonates with good enantioselectivity under extremely mild conditions in the presence of tetrabutyl ammonium chloride as a co-catalyst.The good enantioselectivity in the cycloaddition reaction is attributed to a synergistic interplay between the chiral porphyrin catalysts and the substrate.The mechanism and enantioselectivity of the asymmetric cycloaddition reaction is discussed.
基金supported by the National Basic Research Program of China(2011CB808600)the National Natural Science Foundation of China(21273102)
文摘The dynamic transformations of conformations and aromatic properties of [32]octaphyrins（1.0.1.0.1.0.1.0） through rotating the pyrrolic ring of the macrocycles are demonstrated by theoretical simulations in CH2Cl2 solution. Facile multistep isomeriza- tions involving antiaromatic-Htickel and aromatic-Mobius topologies were also predicted by density functional theory （DFT）. The understanding of changes in topologies and aromaticities of free-base expanded porphrins may provide useful information to build new macrocycles with unique properties.
