Asymmetric Michael/Aromatization Reaction of Azlactones to alpha,beta-Unsaturated Pyrazolones with C-4 Regioselectivity Catalyzed by an Isosteviol-Derived Thiourea Organocatalyst

作者:Geng Zhi Cong; Chen Xiang; Zhang Jin Xin; Li Ning; Chen Jian; Huang Xiao Fei; Zhang Shao Yun; Tao Jing Chao*; Wang Xing Wang
来源:European Journal of Organic Chemistry, 2013, 2013(22): 4738-4743.
DOI:10.1002/ejoc.201300524

摘要

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 alpha,beta-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).