The privileged C_(2)-symmetric rigid phenol-type ligand is more attractive but challenging in asymmetric catalysis.Herein,we designed and synthesized a class of rigid-featured chiral tridentate Phenol-2NO ligands,that...The privileged C_(2)-symmetric rigid phenol-type ligand is more attractive but challenging in asymmetric catalysis.Herein,we designed and synthesized a class of rigid-featured chiral tridentate Phenol-2NO ligands,that incorporate the advantages of both the phenol skeleton and pyrroloimidazolone-based N-oxide moiety,from readily available L-prolinamides in operationally simple two steps and up to 44%overall yield.More importantly,using an achiral quinoline derivative as an additive,the newly developed Phenol-2NO ligand could serve as the anioic ligand upon deprotonative activation to coordinate to Zn(II)to form a highly enantioselective catalyst for the asymmetric Michael-type Friedel-Crafts alkylation reaction of indoles with 2,3-dioxopyrrolidines.Excellent yields(up to 90%)and high enantioselectivities(up to 99%ee)are obtained for a wide range of substrates under mild conditions.Experiments and DFT calculations revealed the reaction mechanism and the origins of the enantioselectivity.This also represented the first activation of phenol-type ligand/metal complex by an achiral organic base as the additive in asymmetric catalysis.展开更多
A quinine-derived thiourea-catalyzed inter-/intramolecular Michael cycloaddition of chromoneoxindole/benzofuranone synthons with 3-substituted methylenebenzofuranones has been established,which constructed enantiomeri...A quinine-derived thiourea-catalyzed inter-/intramolecular Michael cycloaddition of chromoneoxindole/benzofuranone synthons with 3-substituted methylenebenzofuranones has been established,which constructed enantiomerically pure bispiro[benzofuran-oxindole/benzofuran-chromanone]s bearing five consecutive stereocenters including two spiro quaternary carton centers in good yields(up to 93%) with high diastereoselectivities(up to>20:1 dr) and good enantioselectivities(up to>99% ee).Moreover,this is the first example of bifunctional chromone-benzofuranone synthon directed organocatalytic tandem reaction,and also the first example of the bispiro[benzofuran-oxindole] and bispirobenzofuranone,potentially useful in medicinal chemistry.展开更多
基金We thank financial support from NSFC(22061006)Guizhou Provincial Program(GCC[2023]047,GCC[2023]078,ZK[2023]043,ZK[2022]144,ZK[2022]480).
文摘The privileged C_(2)-symmetric rigid phenol-type ligand is more attractive but challenging in asymmetric catalysis.Herein,we designed and synthesized a class of rigid-featured chiral tridentate Phenol-2NO ligands,that incorporate the advantages of both the phenol skeleton and pyrroloimidazolone-based N-oxide moiety,from readily available L-prolinamides in operationally simple two steps and up to 44%overall yield.More importantly,using an achiral quinoline derivative as an additive,the newly developed Phenol-2NO ligand could serve as the anioic ligand upon deprotonative activation to coordinate to Zn(II)to form a highly enantioselective catalyst for the asymmetric Michael-type Friedel-Crafts alkylation reaction of indoles with 2,3-dioxopyrrolidines.Excellent yields(up to 90%)and high enantioselectivities(up to 99%ee)are obtained for a wide range of substrates under mild conditions.Experiments and DFT calculations revealed the reaction mechanism and the origins of the enantioselectivity.This also represented the first activation of phenol-type ligand/metal complex by an achiral organic base as the additive in asymmetric catalysis.
基金financial support from the National Nature Science Foundation of China(Nos.81760625,81660576 and81560563)Projects of Guizhou Province(Nos.[2016]5623,JG[2016]06,[2019]1402,[2017]5609 and[2018]5781)。
文摘A quinine-derived thiourea-catalyzed inter-/intramolecular Michael cycloaddition of chromoneoxindole/benzofuranone synthons with 3-substituted methylenebenzofuranones has been established,which constructed enantiomerically pure bispiro[benzofuran-oxindole/benzofuran-chromanone]s bearing five consecutive stereocenters including two spiro quaternary carton centers in good yields(up to 93%) with high diastereoselectivities(up to>20:1 dr) and good enantioselectivities(up to>99% ee).Moreover,this is the first example of bifunctional chromone-benzofuranone synthon directed organocatalytic tandem reaction,and also the first example of the bispiro[benzofuran-oxindole] and bispirobenzofuranone,potentially useful in medicinal chemistry.
