Diastereoselective synthesis of trans-3,5-disubstituted dihydrofuran-2(3H)-ones via SmI2-mediated reductive coupling of 2-alkylacrylates of N,N-diisopropyl-2-hydroxybenzamide with aldehydes
作者:Yecai Lai、Lijie Sun、Man Ki Sit、Yan Wang、Wei-Min Dai
DOI:10.1016/j.tet.2015.12.009
日期:2016.2
acrylates, in both achiral and chiral forms, for accessing substituted dihydrofuran-2(3H)-ones (γ-butyrolactones). Two major issues, concerning with self-dimerization of α-non-branched aliphatic aldehydes and low diastereoselectivity of the products, render limited application of the reductive coupling protocol in total synthesis of natural products. We report here on a novel type of substituted acrylates derived
io(II)碘化物已被用于介导醛与各种非手性和手性形式的取代丙烯酸酯的还原偶联反应,以获取取代的二氢呋喃2(3 H)-一(γ-丁内酯)。与α-非支链脂族醛的自二聚和产物的低非对映选择性有关的两个主要问题使得还原偶联方案在天然产物的全合成中的应用受到限制。我们在这里报告了一种新型的衍生自2-氨基芳烃(HO-Ar am)的取代丙烯酸酯,例如N,N-二异丙基-2-羟基苯甲酰胺。HO-Ar am的丙烯酸酯使:(a)丙烯酸酯的优先共轭还原比脂族醛的羰基还原优先,从而导致醛的自二聚化减少;(b)在酰胺羰基氧原子和sa(III)之间形成八元环以形成7 / 8-双环过渡态,从而导致the(III)烯醇化物中间体的高度非对映选择性质子化。提供了由HO-Ar am的2-烷基丙烯酸酯和脂族醛合成反式-3,5-二取代的二氢呋喃-2(3 H)-one的实例。