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Paper | Special issue | Vol 95, No. 2, 2017, pp.980-993
Published online, 28th November, 2016
DOI: 10.3987/COM-16-S(S)68
An Enantioselective Synthesis of 2-Imidazolidinones through Bifunctional Thiourea-Catalyzed Tandem Mannich/Cyclization of Isocyanatomalonate Diester

Yusuke Kobayashi, Takuma Yoshida, Takuya Uno, Chihiro Tsukano, and Yoshiji Takemoto*

*Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-shimoadachi-machi, Sakyo-ku, Kyoto 606-8501, Japan

Abstract

A chiral bifunctional thiourea-catalyzed Mannich reaction of diethyl 2-isocyanatomalonate with N-sulfonylimines was described. The tandem cyclization proceeded smoothly after Mannch reaction, directly furnishing chiral 2-imidazolidinones in 72‒99% yields with 83‒98% ees. Sterically demanding sulfonyl group was crucial for aliphatic imines to afford the corresponding product in high enantioselectivity.