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Asymmetric Michael/Aromatization Reaction of Azlactones to α,β‐Unsaturated Pyrazolones with C‐4 Regioselectivity Catalyzed by an Isosteviol‐Derived Thiourea Organocatalyst
Author(s) -
Geng ZhiCong,
Chen Xiang,
Zhang JinXin,
Li Ning,
Chen Jian,
Huang XiaoFei,
Zhang ShaoYun,
Tao JingChao,
Wang XingWang
Publication year - 2013
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201300524
Subject(s) - pyrazolones , chemistry , thiourea , aromatization , organocatalysis , organic chemistry , michael reaction , regioselectivity , catalysis , amine gas treating , enantioselective synthesis
Pyrazoles are an important class of molecular structures with significant biological and pharmaceutical activities. Herein, heterocyclic compounds containing both a pyrazole motif and a masked amino acid structure are synthesized through the asymmetric Michael/aromatization of azlactones to α,β‐unsaturated pyrazolones by using isosteviol‐derived amine thiourea as the organocatalyst. The products are obtained in good yields (up to 93 %) with good diastereoselectivities and good enantioselectivities (up to >10:1 dr , 97 % ee ).