Song Dong, Rostami Ali, West F G
Department of Chemistry, University of Alberta, E3-43 Gunning-Lemieux Chemistry Centre, Edmonton, Alberta, Canada T6G 2G2.
J Am Chem Soc. 2007 Oct 3;129(39):12019-22. doi: 10.1021/ja071041z. Epub 2007 Sep 8.
Simple 1,4-dien-3-ones undergo Lewis acid-catalyzed Nazarov electrocyclization and intermolecular trapping by various azides to furnish 3,4-dihydropyridin-2-ones in moderate to good yields. The reaction is proposed to proceed via nucleophilic trapping of the 2-oxidocyclopentenyl intermediate, followed by Schmidt-type rearrangement to give a transient 1,4-dipole. In unsymmetrical examples, complete regioselectivity in favor of attack on the less substituted side was observed. The 1,4-dipole intermediate then rearranges to the observed dihydropyridone, via either proton transfer or 1,5-hydride shift.
简单的1,4 - 二烯 - 3 - 酮在路易斯酸催化下进行纳扎罗夫电环化反应，并被各种叠氮化物进行分子间捕获，以中等至良好的产率得到3,4 - 二氢吡啶 - 2 - 酮。该反应被认为是通过对2 - 氧化环戊烯基中间体进行亲核捕获，随后进行施密特型重排以产生一个瞬态的1,4 - 偶极子。在不对称的例子中，观察到完全的区域选择性，有利于进攻取代较少的一侧。然后，1,4 - 偶极子中间体通过质子转移或1,5 - 氢迁移重排为观察到的二氢吡啶酮。
