Copper-catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylides andβ-trifluoromethyl-substituted alkenyl heteroarenes was developed for the first time.A wide range of enantioenriched pyrrolidines containin...Copper-catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylides andβ-trifluoromethyl-substituted alkenyl heteroarenes was developed for the first time.A wide range of enantioenriched pyrrolidines containing both heteroarenes and trifluoromethyl group with multiple stereogenic centers could be readily accessible by this method with good to high yields and excellent levels of both stereo-and regioselectivity(up to 99%yield,>20:1 rr,>20:1 dr,and up to 95%ee).Notably,substratecontrolled umpolung-type dipolar cycloaddition was also disclosed in this protocol to achieve regiodivergent synthesis withα-aryl substituted aldimine esters as the dipole precursors.Systematic DFT studies were conducted to explore the origin of the stereo-and regioselectivity of this 1,3-dipolar cycloaddition,and suggest that copper(Ⅱ)salt utilized in this catalytic system could be reduced in-situ to the active copper(Ⅰ)species and might be responsible for the observed high stereo-and regioselectivity.展开更多
Oxygen-vacancies(OVs)play significant roles in semiconductor-based photocatalysis,such as elevating light absorption property,photogenerated carries separation efficiency,molecular activation,and photocatalytic activi...Oxygen-vacancies(OVs)play significant roles in semiconductor-based photocatalysis,such as elevating light absorption property,photogenerated carries separation efficiency,molecular activation,and photocatalytic activity.However,heat-treatment of semiconductors in dangerous H_(2)atmosphere is usually indispensable for OVs formation.In this work,C-doped Bi_(12)O_(17)C_(12)nanosheets were facially heat-treated in H_(2)O vapor(~2.3 vol%)mixed with Ar at 300℃to in-situ introduce OVs by the proposed reactions of C(s)+H_(2)O(g)→CO(g)+H_(2)(g)and H_(2)(g)+O_(Lattice)→H_(2)O(g)+OV.The formation of OVs,which was confirmed by electron paramagnetic resonance(EPR),can narrow the band gap,and enhance the photogenerated e~-/h~+separation efficiency on Bi_(12)O_(17)C_(12).Moreover,OVs-rich Bi_(12)O_(17)C_(12)nanosheets can facilitate molecular O_(2)activation and produce more reactive oxygen species(ROS),especially~1 O_(2),which greatly improve the NO to NO_(3)~-conversion efficiency with NO removal rate of~63%and NO_(3)~-production selectivity of~92.6%.The present work will bring new insights into the construction and roles of OVs in semiconductor-based photocatalysis.展开更多
基金supported by the National Natural Science Foundation of China(22071186,22071187,22073067,22101216,22271226,21933003,22193020,22193023)the National Youth Talent Support Program+3 种基金the Natural Science Foundation of Hubei Province(2020CFA0362021CFA069)the Fundamental Research Funds for the Central Universities(2042022kf1180,2042022kf1040)the Shenzhen Nobel Prize Scientists Laboratory Project(C17783101)the Guangdong Provincial Key Laboratory of Catalytic Chemistry(2020B121201002)。
文摘Copper-catalyzed asymmetric 1,3-dipolar cycloaddition of azomethine ylides andβ-trifluoromethyl-substituted alkenyl heteroarenes was developed for the first time.A wide range of enantioenriched pyrrolidines containing both heteroarenes and trifluoromethyl group with multiple stereogenic centers could be readily accessible by this method with good to high yields and excellent levels of both stereo-and regioselectivity(up to 99%yield,>20:1 rr,>20:1 dr,and up to 95%ee).Notably,substratecontrolled umpolung-type dipolar cycloaddition was also disclosed in this protocol to achieve regiodivergent synthesis withα-aryl substituted aldimine esters as the dipole precursors.Systematic DFT studies were conducted to explore the origin of the stereo-and regioselectivity of this 1,3-dipolar cycloaddition,and suggest that copper(Ⅱ)salt utilized in this catalytic system could be reduced in-situ to the active copper(Ⅰ)species and might be responsible for the observed high stereo-and regioselectivity.
基金supported by the National Natural Science Foundation of China(51902121,52073110,22071072,51872107,21975090,and 21801086)the Fundamental Research Funds for the Central Universities of China(2662018QD011,2662018PY052,and 2662019PY023)the Natural Science Foundation of Hubei Province(2019CFB322)。
基金financially supported by the National Natural Science Foundation of China(Nos.21703075,51872107,52073110,22002047)Natural Science Foundation of Hubei Province(Nos.2020CFB694,2020CFB394)Fundamental Research Funds for the Central Universities(Nos.2662020LXPY005,2662019QD018)。
文摘Oxygen-vacancies(OVs)play significant roles in semiconductor-based photocatalysis,such as elevating light absorption property,photogenerated carries separation efficiency,molecular activation,and photocatalytic activity.However,heat-treatment of semiconductors in dangerous H_(2)atmosphere is usually indispensable for OVs formation.In this work,C-doped Bi_(12)O_(17)C_(12)nanosheets were facially heat-treated in H_(2)O vapor(~2.3 vol%)mixed with Ar at 300℃to in-situ introduce OVs by the proposed reactions of C(s)+H_(2)O(g)→CO(g)+H_(2)(g)and H_(2)(g)+O_(Lattice)→H_(2)O(g)+OV.The formation of OVs,which was confirmed by electron paramagnetic resonance(EPR),can narrow the band gap,and enhance the photogenerated e~-/h~+separation efficiency on Bi_(12)O_(17)C_(12).Moreover,OVs-rich Bi_(12)O_(17)C_(12)nanosheets can facilitate molecular O_(2)activation and produce more reactive oxygen species(ROS),especially~1 O_(2),which greatly improve the NO to NO_(3)~-conversion efficiency with NO removal rate of~63%and NO_(3)~-production selectivity of~92.6%.The present work will bring new insights into the construction and roles of OVs in semiconductor-based photocatalysis.
