The through-space and through-bond interactions of molecular orbitals in [2,2] paracyclophane are studied by the approved MS-X. method with overlapping atomic-sphere. The calculation results show the through-space in...The through-space and through-bond interactions of molecular orbitals in [2,2] paracyclophane are studied by the approved MS-X. method with overlapping atomic-sphere. The calculation results show the through-space interactions are exponential flareout with increasing of the distance of two orbitals, and.both through-space interactions and through-bond interactions are sizable but those two interactions oppose each other causing the net splitting to be small. Transition-state procedure was used to calculate ionization potentials, the results are in agreement with the PE-spectra.展开更多
Chiral[2.2]paracyclophane(PCP)is an intriguing prevalent scaffold widely utilized inπ-stacked polymers,luminescent materials,and asymmetric catalysis.However,current synthetic methods to access chiral PCP derivatives...Chiral[2.2]paracyclophane(PCP)is an intriguing prevalent scaffold widely utilized inπ-stacked polymers,luminescent materials,and asymmetric catalysis.However,current synthetic methods to access chiral PCP derivatives are still limited to physical separation and chemical or kinetic resolution.The direct desymmetric functionalization of nonsubstituted PCP has been a challenge since its discovery 70 years ago.Herein,we present a catalytic desymmetric dearomatization cyclopropanation reaction of PCP,providing rapid access to enantioenriched PCP cyclopropyl carboxylates with continuous tertiary/quaternary/quaternary chiral centers.The application of the chiral PCPs obtained has also been demonstrated by transformation to structurally novel C_(2) symmetric dirhodium catalysts.Of equal importance,detailed density functional theory calculations have been carried out to reveal the mechanism of this reaction.The key to this success is a structurally symmetric bulky C_(4) dirhodium catalyst:noncovalent interactions exist between substrates and catalysts,which form a cavity to host substrates,and mainly affect the regio-and enantioselectivity.展开更多
Polyhaloalkanes are broadly useful yet environmentally harmful stock chemicals,therefore the development of adsorbent materials with capacity and selectivity for polyhaloalkane vapors is highly desirable.Here we repor...Polyhaloalkanes are broadly useful yet environmentally harmful stock chemicals,therefore the development of adsorbent materials with capacity and selectivity for polyhaloalkane vapors is highly desirable.Here we report a novel macrocycle WreathArene,a fluorinated C;-symmetrical [1;]-paracyclophane.In the crysalline state,WreathArene features vip-adaptive polymorphism for polyhaloalkanes including chloroform,tribromomethane,1,1,2-trichloroethane,and 1,2-dibromoethane.Non-covalent C-halogen…πinteractions are observed in all of these host-vip structures.Based on these properties,the activated WreathArene crystals can be utilized as a selective and recyclable adsorbent for polyhaloalkane vapors with excellent capacity under user-friendly conditions.展开更多
An environmentally friendly and transition metal-free method for the preparation of chiral α- hydroxysilanes was developed. Enantioselective addition of a silicon nucleophile to aromatic aldehydes in water was achiev...An environmentally friendly and transition metal-free method for the preparation of chiral α- hydroxysilanes was developed. Enantioselective addition of a silicon nucleophile to aromatic aldehydes in water was achieved by using a new hydroxyl-functionalized chiral carbene as catalyst, affording the corresponding products in good yields and moderate enantioselectivities.展开更多
文摘The through-space and through-bond interactions of molecular orbitals in [2,2] paracyclophane are studied by the approved MS-X. method with overlapping atomic-sphere. The calculation results show the through-space interactions are exponential flareout with increasing of the distance of two orbitals, and.both through-space interactions and through-bond interactions are sizable but those two interactions oppose each other causing the net splitting to be small. Transition-state procedure was used to calculate ionization potentials, the results are in agreement with the PE-spectra.
基金support of the Natural Science Foundation of China and Shandong Province(grant nos.21971149,92156007,21933003,ZR2019ZD45,and ZR2020KB005).
文摘Chiral[2.2]paracyclophane(PCP)is an intriguing prevalent scaffold widely utilized inπ-stacked polymers,luminescent materials,and asymmetric catalysis.However,current synthetic methods to access chiral PCP derivatives are still limited to physical separation and chemical or kinetic resolution.The direct desymmetric functionalization of nonsubstituted PCP has been a challenge since its discovery 70 years ago.Herein,we present a catalytic desymmetric dearomatization cyclopropanation reaction of PCP,providing rapid access to enantioenriched PCP cyclopropyl carboxylates with continuous tertiary/quaternary/quaternary chiral centers.The application of the chiral PCPs obtained has also been demonstrated by transformation to structurally novel C_(2) symmetric dirhodium catalysts.Of equal importance,detailed density functional theory calculations have been carried out to reveal the mechanism of this reaction.The key to this success is a structurally symmetric bulky C_(4) dirhodium catalyst:noncovalent interactions exist between substrates and catalysts,which form a cavity to host substrates,and mainly affect the regio-and enantioselectivity.
基金Financial support from the National Natural Science Foundation of China (Nos. 21672227, 21922113, 21988102, 22071257)Chinese Academy of Sciences (Nos. XDB17000000)+2 种基金the National Key Research and Development Program (No. 2017YFA0206903)K. C.Wong Education Foundationthe TIPC Director’s Fund。
文摘Polyhaloalkanes are broadly useful yet environmentally harmful stock chemicals,therefore the development of adsorbent materials with capacity and selectivity for polyhaloalkane vapors is highly desirable.Here we report a novel macrocycle WreathArene,a fluorinated C;-symmetrical [1;]-paracyclophane.In the crysalline state,WreathArene features vip-adaptive polymorphism for polyhaloalkanes including chloroform,tribromomethane,1,1,2-trichloroethane,and 1,2-dibromoethane.Non-covalent C-halogen…πinteractions are observed in all of these host-vip structures.Based on these properties,the activated WreathArene crystals can be utilized as a selective and recyclable adsorbent for polyhaloalkane vapors with excellent capacity under user-friendly conditions.
基金Financial support from the National Natural Science Foundation of China(Nos.21372144,81473085)Department of Science and Technology of Shandong Province
文摘An environmentally friendly and transition metal-free method for the preparation of chiral α- hydroxysilanes was developed. Enantioselective addition of a silicon nucleophile to aromatic aldehydes in water was achieved by using a new hydroxyl-functionalized chiral carbene as catalyst, affording the corresponding products in good yields and moderate enantioselectivities.
