Enantioselective Michael Addition of Aromatic Ketones to Nitroolefins Catalyzed by Bifunctional Thioureas and Mechanistic Insight

✍ Scribed by Bai-Lin Li; Yi-Feng Wang; Shu-Ping Luo; Ai-Guo Zhong; Zhao-Bo Li; Xiao-Hua Du; Dan-Qian Xu

• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 774 KB
• Volume: 2010
• Category: Article
• ISSN: 1434-193X
• DOI: 10.1002/ejoc.200900932

✦ Synopsis

Abstract

A highly enantioselective Michael reaction of aromatic ketones with nitroolefins was accomplished in the presence of a chiral bifunctional primary amine–thiourea catalyst and 4‐nitrobenzoic acid as the co‐catalyst; the corresponding adducts were obtained in excellent enantioselectivities (up to 99 % ee) and yields (up to 98 %). The catalytic mechanism of the Michael reaction was confirmed through the ESI‐MS detection of proposed reaction intermediates and the ^1^H NMR detection of hydrogen bonding between thiourea and the nitroolefins. DFT calculations showed that chiral moieties of the thiourea impacted the yields and enantioselectivities of the adducts remarkably, which corresponds to the observed experimental results.