In this paper,we report a full account of the synthesis of dimeric hexahydropyrroloindole alkaloids and its analogues.The key feature of our new strategy is the novel catalytic copper(10%)mediated intramolecular aryla...In this paper,we report a full account of the synthesis of dimeric hexahydropyrroloindole alkaloids and its analogues.The key feature of our new strategy is the novel catalytic copper(10%)mediated intramolecular arylations of o-haloanilides followed by intermolecular oxidative dimerization of the resulting oxindoles in one pot.This sequential reaction leads to the key intermediates for the synthesis of(+)-chimonanthine,(+)-folicanthine,(-)-calycanthine and(-)-ditryptophenaline.Graphical Abstract In the presence of catalytic amount of cuprous iodide(10%),an intramolecular arylation of ohaloanilides followed by an intermolecular oxidative dimerization of the resulting oxindoles leads to a commonintermediate for the synthesis of(+)-chimonanthine,(+)-folicanthine and(-)-calycanthine.Based on this cascade sequence,we also developed a flexible strategy towards the asymmetric syntheses of dimeric HPI alkaloids(-)-ditryptophenaline and its analogues.展开更多
Covalent bonds arise from the overlap of the electronic clouds in the internucleus region, which is a pure quantum effect and cannot be obtained in any classical way. If the intermolecular interaction is of covalent c...Covalent bonds arise from the overlap of the electronic clouds in the internucleus region, which is a pure quantum effect and cannot be obtained in any classical way. If the intermolecular interaction is of covalent character, the result from direct applications of classical simulation methods to the molecular system would be questionable. Here, we analyze the special intermolecular interaction between two NO molecules based on quantum chemical calculation. This weak intermolecular interaction, which is of covalent character, is responsible for the formation of the NO dimer,（NO）2, in its most stable conformation, a cis conformation. The natural bond orbital（NBO） analysis gives an intuitive illustration of the formation of the dimer bonding and antibonding orbitals concomitant with the breaking of the πbonds with bond order 0.5of the monomers. The dimer bonding is counteracted by partially filling the antibonding dimer orbital and the repulsion between those fully or nearly fully occupied nonbonding dimer orbitals that make the dimer binding rather weak. The direct molecular mechanics（MM） calculation with the UFF force fields predicts a trans conformation as the most stable state, which contradicts the result of quantum mechanics（QM）. The lesson from the investigation of this special system is that for the case where intermolecular interaction is of covalent character, a specific modification of the force fields of the molecular simulation method is necessary.展开更多
Perfluorinated/polyfluorinated substances(PFAS)are synthetic organic compounds widely used in over 200 industrial and consumer applications since the 1950s.In recent years,numerous emerging PFAS alternatives such as h...Perfluorinated/polyfluorinated substances(PFAS)are synthetic organic compounds widely used in over 200 industrial and consumer applications since the 1950s.In recent years,numerous emerging PFAS alternatives such as hexafluoropropylene oxide dimer acid(HFPO-DA,GenX),4,8-dioxa-3Hperfluorononanoic acid,and 6:2 chlorinated polyfluorinated ether sulfonate(6:2 Cl-PFESA,F-53B)have replaced restricted legacy PFAS.However,the environmental and human health effects of these alternatives remain poorly understood.Since they are resistant to degradation,these persistent compounds have been detected globally in water,soil,dust,and biological samples from wildlife,marine organisms,and humans.The detection of PFAS in maternal blood,umbilical cord blood,amniotic fluid,and breast milk raises concerns that humans may be exposed to these chemicals during vulnerable fetal developmental stages[1].展开更多
基金This work was supported by Grants from Natural Science Foundation of China(20925205 and 21332007)the Program for Changjiang Scholars and Innovative Research Team in University(IRT13095)+1 种基金Yunnan Provincial Science and Technology Department(2010GA014)the Program for Yunling Scholars.Dr.Xiaonian Li of the Kunming Institute of Botany is gratefully acknowledged for X-ray crystallographic analysis of compound 23.CCDC 1409209(23).
文摘In this paper,we report a full account of the synthesis of dimeric hexahydropyrroloindole alkaloids and its analogues.The key feature of our new strategy is the novel catalytic copper(10%)mediated intramolecular arylations of o-haloanilides followed by intermolecular oxidative dimerization of the resulting oxindoles in one pot.This sequential reaction leads to the key intermediates for the synthesis of(+)-chimonanthine,(+)-folicanthine,(-)-calycanthine and(-)-ditryptophenaline.Graphical Abstract In the presence of catalytic amount of cuprous iodide(10%),an intramolecular arylation of ohaloanilides followed by an intermolecular oxidative dimerization of the resulting oxindoles leads to a commonintermediate for the synthesis of(+)-chimonanthine,(+)-folicanthine and(-)-calycanthine.Based on this cascade sequence,we also developed a flexible strategy towards the asymmetric syntheses of dimeric HPI alkaloids(-)-ditryptophenaline and its analogues.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.90403007 and 10975044)the Key Subject Construction Project of Hebei Provincial Universities,China+2 种基金the Research Project of Hebei Education Department,China(Grant Nos.Z2012067 and Z2011133)the National Natural Science Foundation of China(Grant No.11147103)the Open Project Program of State Key Laboratory of Theoretical Physics,Institute of Theoretical Physics,Chinese Academy of Sciences,China(Grant No.Y5KF211CJ1)
文摘Covalent bonds arise from the overlap of the electronic clouds in the internucleus region, which is a pure quantum effect and cannot be obtained in any classical way. If the intermolecular interaction is of covalent character, the result from direct applications of classical simulation methods to the molecular system would be questionable. Here, we analyze the special intermolecular interaction between two NO molecules based on quantum chemical calculation. This weak intermolecular interaction, which is of covalent character, is responsible for the formation of the NO dimer,（NO）2, in its most stable conformation, a cis conformation. The natural bond orbital（NBO） analysis gives an intuitive illustration of the formation of the dimer bonding and antibonding orbitals concomitant with the breaking of the πbonds with bond order 0.5of the monomers. The dimer bonding is counteracted by partially filling the antibonding dimer orbital and the repulsion between those fully or nearly fully occupied nonbonding dimer orbitals that make the dimer binding rather weak. The direct molecular mechanics（MM） calculation with the UFF force fields predicts a trans conformation as the most stable state, which contradicts the result of quantum mechanics（QM）. The lesson from the investigation of this special system is that for the case where intermolecular interaction is of covalent character, a specific modification of the force fields of the molecular simulation method is necessary.
文摘Perfluorinated/polyfluorinated substances(PFAS)are synthetic organic compounds widely used in over 200 industrial and consumer applications since the 1950s.In recent years,numerous emerging PFAS alternatives such as hexafluoropropylene oxide dimer acid(HFPO-DA,GenX),4,8-dioxa-3Hperfluorononanoic acid,and 6:2 chlorinated polyfluorinated ether sulfonate(6:2 Cl-PFESA,F-53B)have replaced restricted legacy PFAS.However,the environmental and human health effects of these alternatives remain poorly understood.Since they are resistant to degradation,these persistent compounds have been detected globally in water,soil,dust,and biological samples from wildlife,marine organisms,and humans.The detection of PFAS in maternal blood,umbilical cord blood,amniotic fluid,and breast milk raises concerns that humans may be exposed to these chemicals during vulnerable fetal developmental stages[1].
