Author
Zhao Han
Bio: Zhao Han is an academic researcher from Zhejiang University. The author has contributed to research in topics: Enantioselective synthesis & Lactam. The author has co-authored 1 publications.
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TL;DR: Chiral phosphoric acids (CPAs) have been used as efficient organocatalysts since the first examples were reported 18 years ago by Akiyama and Terada as mentioned in this paper .
Abstract: Chiral phosphoric acids (CPAs) have been used as efficient organocatalysts since the first examples were reported 18 years ago by Akiyama and Terada. Although they were originally developed for enantioselective...
4 citations
TL;DR: This asymmetric organocatalysis protocol enables efficient synthesis of unnatural α-amino acid derivatives with a tetrasubstituted stereogenic center and an alkyne moiety with up to 99% yield and 98% ee, resulting in operationally simple conditions, short reaction time, and broad substrate scope.
3 citations
TL;DR: In this paper , an enantioselective addition of 5-amino-isoxazoles with β,γ-alkynyl-α-ketimino esters catalyzed by a chiral phosphoric acid has been developed.
Abstract: An enantioselective addition of 5-amino-isoxazoles with β,γ-alkynyl-α-ketimino esters catalyzed by a chiral phosphoric acid has been developed. This procedure allowed the formation of quaternary α-isoxazole-α-alkynyl amino acid derivatives with high yields (up to 99%) and good to excellent enantioselectivities (up to 97%), and the corresponding products enabled many further elaborations. The control experiment revealed that the hydrogen-bonding interaction of 5-amino-isoxazole with the chiral phosphoric acid played a vital role in the enantioselectivity, and the transition state of the reaction was proposed.
3 citations
TL;DR: A chiral phosphoric acid-catalyzed enantioselective aza-Friedel-Crafts reaction of 5-aminopyrazole derivatives with cyclic ketimines attached to a neutral functional group is reported in this article .
Abstract: A chiral phosphoric acid-catalyzed enantioselective aza-Friedel-Crafts reaction of 5-aminopyrazole derivatives with cyclic ketimines attached to a neutral functional group is reported. This protocol allows the formation of pyrazole-based C2-quaternary indolin-3-ones with high enantioselectivities and regioselectivities. Moreover, gram-scale synthesis of the 5-aminopyrazole-based C2-quaternary indolin-3-ones was performed, with no decrease in the yield and enantioselectivity.
2 citations
TL;DR: In this article , the authors present a review of recent advances in asymmetric aza-Friedel-Crafts reactions mediated by organocatalysts and explain the mechanistic interpretation with the origin of stereoselectivity.
Abstract: The aza-Friedel–Crafts reaction allows an efficient coupling of electron-rich aromatic systems with imines for the facile incorporation of aminoalkyl groups into the aromatic ring. This reaction has a great scope of forming aza-stereocenters which can be tuned by different asymmetric catalysts. This review assembles recent advances in asymmetric aza-Friedel–Crafts reactions mediated by organocatalysts. The mechanistic interpretation with the origin of stereoselectivity is also explained.