Stereoselective synthesis of 3,4-disubstituted and 3,4,5-trisubstituted piperidines by Lewis acid-catalysed ene cyclisation of 4-aza-1,7-dienes
作者:Stephen M. Walker、Jodi T. Williams、Alexander G. Russell、Benson M. Kariuki、John S. Snaith
DOI:10.1039/b708139a
日期:——
there was a fine balance between the desired ene cyclisation and the competing hetero-Diels-Alder reaction, with the product distribution being influenced by the activating group on the enophile, the nature of the ene component, and the Lewis acid used. Activation of the enophile with an oxazolidinone function facilitated Lewis acid-catalysed cyclisation to afford mixtures of ene and hetero-Diels-Alder
各种4-氮杂-1,7-二烯的热或路易斯酸催化的烯环化得到3,4-二取代或3,4,5-三取代的哌啶。尽管该反应不适合路易斯酸催化,但是用单酯活化亲油体促进了热烯环化。与亲脂体上的其他活化基团一起发现路易斯酸催化很容易,尽管所需的烯环化和竞争性杂-Diels-Alder反应之间存在良好的平衡,产物分布受烯基上活化基团的影响。亲烯体,烯组分的性质以及所用的路易斯酸。具有恶唑烷酮功能的亲油体的活化促进了路易斯酸催化的环化作用,得到了烯和杂-Diels-Alder产物的混合物。