The cascade reactions of alkyl α-diazoesters and ynones using Al(OTf)_(3) as the catalyst are described.A series of 4-substituted pyrazoles were obtained via [3+2] cycloaddition,1,5-ester shift,1,3-H shift,and N-H in...The cascade reactions of alkyl α-diazoesters and ynones using Al(OTf)_(3) as the catalyst are described.A series of 4-substituted pyrazoles were obtained via [3+2] cycloaddition,1,5-ester shift,1,3-H shift,and N-H insertion process.Deuterium labelling experiments,kinetic studies and control experiments were carried out for the rationalization of the mechanism.展开更多
A highly enantioselective 1,3-dipolar cycloaddition ofα-substituted diazoesters with exocyclic enones was achieved with chiral scandium(III)/N,N’-dioxide complex as the catalyst.This protocol provided a facile and e...A highly enantioselective 1,3-dipolar cycloaddition ofα-substituted diazoesters with exocyclic enones was achieved with chiral scandium(III)/N,N’-dioxide complex as the catalyst.This protocol provided a facile and efficient route to optically active 1-pyrazoline-based spirochromanones and others with good outcomes(up to 97%yield,98%ee with>95:5 dr).Moreover,enantioenriched 2-pyrazoline-based spirochromanones were also accessible by switchingα-substituted diazoesters toα-diazoacetates.The further specific transformations of chiral pyrazoline-based spiro-compounds to spirocyclopropane derivatives were disclosed as well.展开更多
基金supported by the National Natural Science Foundation of China(Nos.21625205 and U19A2014)。
文摘The cascade reactions of alkyl α-diazoesters and ynones using Al(OTf)_(3) as the catalyst are described.A series of 4-substituted pyrazoles were obtained via [3+2] cycloaddition,1,5-ester shift,1,3-H shift,and N-H insertion process.Deuterium labelling experiments,kinetic studies and control experiments were carried out for the rationalization of the mechanism.
基金This work was supported by the National Natural Science Foundation of China(U19A2014,21890723).
文摘A highly enantioselective 1,3-dipolar cycloaddition ofα-substituted diazoesters with exocyclic enones was achieved with chiral scandium(III)/N,N’-dioxide complex as the catalyst.This protocol provided a facile and efficient route to optically active 1-pyrazoline-based spirochromanones and others with good outcomes(up to 97%yield,98%ee with>95:5 dr).Moreover,enantioenriched 2-pyrazoline-based spirochromanones were also accessible by switchingα-substituted diazoesters toα-diazoacetates.The further specific transformations of chiral pyrazoline-based spiro-compounds to spirocyclopropane derivatives were disclosed as well.
