Diphenylprolinol Silyl Ether Catalyzed Asymmetric Michael Reaction of Nitroalkanes and β,β-Disubstituted α,β-Unsaturated Aldehydes for the Construction of All-Carbon Quaternary Stereogenic Centers
作者:Yujiro Hayashi、Yuya Kawamoto、Masaki Honda、Daichi Okamura、Shigenobu Umemiya、Yuka Noguchi、Takasuke Mukaiyama、Itaru Sato
DOI:10.1002/chem.201403588
日期:2014.9.15
synthetic equivalent of the asymmetric Michael reaction of ethyl and acetyl substituents by means of radical denitration and Nef reaction, respectively. The short asymmetric synthesis of (S)‐ethosuximide with a quaternary carbon center was accomplished by using the present asymmetric Michael reaction as the key step. The reaction mechanism that involves the E/Z isomerization of α,β‐unsaturated aldehydes
二苯基脯氨醇甲硅烷基醚催化硝基烷与β,β-二取代的α,β-不饱和醛的不对称迈克尔反应,得到1,4加成产物,具有全碳四元立体立体中心,具有出色的对映选择性。对于β-取代基(例如β-芳基和β-烷基),该反应一般,并且硝基甲烷和硝基乙烷均可使用。分别通过自由基脱硝和Nef反应,认为硝基乙烷的添加是乙基和乙酰基取代基的不对称迈克尔反应的合成等价物。通过使用当前的不对称迈克尔反应作为关键步骤,完成了具有季碳中心的(S)-乙硫酰亚胺的短时不对称合成。涉及E的反应机理讨论了α,β-不饱和醛的/ Z异构化,麦克尔逆反应以及硝基甲烷和硝基乙烷之间不同的反应性。