Chirality or handedness,i.e.,the non-superimposability of a structure(lacking a plane or center of symmetry)with its mirrorimage,strongly impacts various chemistry/biology areas,and plays an important role,e.g.,in mat...Chirality or handedness,i.e.,the non-superimposability of a structure(lacking a plane or center of symmetry)with its mirrorimage,strongly impacts various chemistry/biology areas,and plays an important role,e.g.,in materials chemistry[1].In medicinal chemistry it is critical to evaluate the therapeutic and toxicological properties of all stereoisomers of a drug molecule because diastereoisomers and enantiomers may exhibit distinct biological and pharmacological activities[2].展开更多
The first example of stereoconvergent 1,3-dipolar cycloaddition of nitrile oxides and nitrile imines with E/Z isomeric mixture of electron-deficient olefins is reported,delivering isoxazolines and pyrazolines bearing ...The first example of stereoconvergent 1,3-dipolar cycloaddition of nitrile oxides and nitrile imines with E/Z isomeric mixture of electron-deficient olefins is reported,delivering isoxazolines and pyrazolines bearing two vicinal stereogenic tertiary and trifluoromethylated quaternary carbon centers with perfect regioand diastereoselectivities.The possibility of concerted cycloaddition/epimerization sequence under basic condition to form the thermodynamically stable diastereomers is excluded through some control experiments and DFT calculations,and a stepwise mechanism is proposed.展开更多
基金the financial support from the National Natural Science Foundation of China(21772151)Natural Science Foundation of Hubei Province(2018CFA084)。
文摘Chirality or handedness,i.e.,the non-superimposability of a structure(lacking a plane or center of symmetry)with its mirrorimage,strongly impacts various chemistry/biology areas,and plays an important role,e.g.,in materials chemistry[1].In medicinal chemistry it is critical to evaluate the therapeutic and toxicological properties of all stereoisomers of a drug molecule because diastereoisomers and enantiomers may exhibit distinct biological and pharmacological activities[2].
基金the financial support for this investigation from the National Natural Science Foundation of China(Nos.21772151,22072111)the Fundamental Research Funds for Central Universities(No.WUT:2021IVA121).
文摘The first example of stereoconvergent 1,3-dipolar cycloaddition of nitrile oxides and nitrile imines with E/Z isomeric mixture of electron-deficient olefins is reported,delivering isoxazolines and pyrazolines bearing two vicinal stereogenic tertiary and trifluoromethylated quaternary carbon centers with perfect regioand diastereoselectivities.The possibility of concerted cycloaddition/epimerization sequence under basic condition to form the thermodynamically stable diastereomers is excluded through some control experiments and DFT calculations,and a stepwise mechanism is proposed.
