Substrate-Controlled Michael Additions of Titanium Enolates from Chiral α-Benzyloxy Ketones to Conjugated Nitroalkenes
作者:Alejandro Gómez-Palomino、Adrián Barrio、Pedro García-Lorente、Pedro Romea、Fèlix Urpí、Mercè Font-Bardia
DOI:10.1002/ejoc.201701055
日期:2017.10.17
formation of dimetallic enolates that increase the reactivity of the enolate and direct the approach of the nitroalkene. Importantly, the most appropriate Lewis acid depends on the electrophilic partner: TiCl4 is the most suitable Lewis acid for β-aryl-nitroalkenes, whereas the best results for β-alkyl-nitroalkenes are obtained with SnCl4. Finally, the nitro group of the resultant compounds can be converted
路易斯酸介导的底物控制的手性 α-苄氧基酮的钛 (IV) 烯醇化物与共轭硝基烯烃的反应得到 2,4-anti-4,5-syn Michael 加合物,产率和非对映体比例良好。补充路易斯酸在这些转化的结果中起着关键作用,这可能是由于形成了双金属烯醇化物,增加了烯醇化物的反应性并引导硝基烯烃的接近。重要的是,最合适的路易斯酸取决于亲电伙伴:TiCl4 是最适合 β-芳基-硝基烯烃的路易斯酸,而使用 SnCl4 可获得 β-烷基-硝基烯烃的最佳结果。最后,所得化合物的硝基可以在温和的条件下转化为相应的胺、肟和腈基,