The palladium-catalysed vinylic substitution of vinyl triflates with β-substituted-α,β-unsaturated carbonyl compounds. An application to the synthesis of cardenolides
作者:Antonio Arcadi、Sandro Cacchi、Giancarlo Fabrizi、Fabio Marinelli、Paola Pace
DOI:10.1016/0040-4020(96)00303-1
日期:1996.5
Vinyl triflates react with β-substituted-α,β-unsaturated aldehydes, ketones, and esters in the presence of catalytic amounts of Pd(OAc)2 and an exeess of KOAc, omitting phosphine ligands, to give vinylic substitution products in good to high yield with high regioselectivity. The added vinyl unit is preferentially linked to the β-carbon atom. As to the stereochemistry, vinylic substitution products
在催化量的Pd(OAc)2和KOAc的存在下,乙烯基三氟甲磺酸酯与β-取代的α,β-不饱和醛,酮和酯反应,省去了膦配体,从而得到了高至高的乙烯基取代产物具有高区域选择性的收率。添加的乙烯基单元优先连接至β-碳原子。关于立体化学,乙烯基取代产物在预先存在的β-取代基的同一侧上含有羰基。事实证明,使用KOAc不仅优于叔胺,而且在添加或不添加盐(例如LiCl和n -Bu 4)的情况下均优于碳酸或碳酸氢盐碱。NCl。报道了该反应在腰果内酯衍生物的合成中的应用。根据β-取代的α,β-不饱和羰基化合物的性质,该反应可产生氢乙烯基化(正式的共轭加成)产物。