PdI2-Catalyzed Coupling–Cyclization Reactions Involving Two Different 2,3-Allenols: An Efficient Synthesis of 4-(1′,3′-Dien-2′-yl)-2,5-dihydrofuran Derivatives
作者:Youqian Deng、Jing Li、Shengming Ma
DOI:10.1002/chem.200800167
日期:2008.5.9
Transition-metal-catalyzed dimeric coupling-cyclization reactions of two different 2,3-allenols afforded 4-(1',3'-dien-2'-yl)-2,5-dihydrofuran derivatives 3. 2-Substituted 2,3-allenols 1 cyclized to form the 2,5-dihydrofuran ring, whereas the 2-unsubstituted 2,3-allenols 2 provided the 1,3-diene unit at the 4-position. The reaction is proposed to proceed through an oxypalladation, insertion, and beta-hydroxide
两种不同的2,3-烯丙醇的过渡金属催化二聚偶联-环化反应提供了4-(1',3'-dien-2'-yl)-2,5-二氢呋喃衍生物3。2-取代的2,3 -烯醇1环化形成2,5-二氢呋喃环,而2-未取代的2,3-烯醇2在4-位提供1,3-二烯单元。建议该反应通过羟钯,插入和β-羟基消除过程进行。通过消除β-羟基以高E立体选择性形成C = C双键。