Regio- and Stereoselective Allylindation of Allenols Regulated by a Hydroxyl-Chelated Bicyclic Transition State
Regio- and Stereoselective Allylindation of Allenols Regulated by a Hydroxyl-Chelated Bicyclic Transition State
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由羟基螯合双环过渡态调控的二烯醇的区域和立体选择性烯丙基化
DOI：
10.1021/ja954318g
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发表时间：
1996
影响因子：
15
通讯作者：
Y. Butsugan
中科院分区：
文献类型：
--
作者：
S. Araki;H. Usui;Motoshi Kato;Y. Butsugan
从理论和实践的角度来看，不饱和化合物的碳金属化是有机金属化学中最重要的过程之一。 1 迄今为止，已使用多种不饱和底物，例如烯烃和炔烃；然而，丙二烯及其衍生物受到的关注相对较少。 2 我们最近证明，烯丙基倍半卤化铟与末端炔醇发生立体选择性而非区域选择性反应，生成烯丙基化产物。 3 在该反应中，结果表明相邻羟基的存在对于烯丙基化的顺利进行至关重要；羟基在不形成醇铟的情况下与铟配位并促进炔醇的烯丙基化。为了检验这种基于羟基螯合的加速和选择性控制的普遍性，我们对几种含羟基的烯烃和炔烃进行了烯丙基化，发现与炔醇情况不同，联烯醇与烯丙基倍半卤化物的烯丙基化进行，具有优异的区域和立体选择性，得到(E)-2， 6-庚二烯-1-醇衍生物的产率很高。联烯醇的烯丙基化反应在 DMF 中于约 140°C 下进行 4 小时（方案 1）。 4 结果总结于表 1 中。烯丙基倍半碘选择性地烯丙基化 2, 3-丁二烯-1-醇的末端碳，定量生成 2, 6-庚二烯-1-醇（条目 1）。通过红外光谱和与真实样品的比较，确定双键的立体化学为E，5 表明铟试剂从丙二烯顺式表面添加到羟甲基上。在反应混合物中没有检测到其他区域异构体和立体异构体。对于γ-取代的烯丙基倍半溴化铟，偶联选择性地发生在γ-碳上（条目2-4）。丙二烯醇 C4-碳上的取代基显示不显着
Carbometalation of unsaturated compounds is one of the most important procedures in organometallic chemistry from both theoretical and practical standpoints. 1 A variety of unsaturated substrates such as alkenes and alkynes have hitherto been employed; however, allenes and their derivatives have received relatively little attention. 2 We have recently demonstrated that allylic indium sesquihalides react, stereoselectively but not regioselectively, with terminal alkynols to give allylindation products. 3 In this reaction, it was shown that the presence of a neighboring hydroxyl group is essential for smooth allylindation; the hydroxyl group, without formation of the indium alkoxide, coordinates to indium and facilitates the allylation of alkynols. In order to examine the generality of this acceleration and selectivity control based on the hydroxyl chelation, we have undertaken allylindation of several hydroxyl-containing alkenes and alkynes and found that allylindation of allenols with allylic indium sesquihalides proceeds, unlike the alkynol cases, with excellent regio-and stereoselectivity to give (E)-2, 6-heptadien-1-ol derivatives in high yields.The allylindation of allenols was conducted in DMF at about 140 C for 4 h (Scheme 1). 4 Results are summarized in Table 1. Allylindium sesquiiodide allylated selectively the terminal carbon of 2, 3-butadien-1-ol yielding 2, 6-heptadien-1-ol quantitatively (entry 1). The stereochemistry of the double bond was determined to be E, by the IR spectrum and comparison with an authentic sample, 5 implying that the indium reagent added from the face of allene syn to the hydroxymethyl group. No other regio-and stereoisomers were detected in the reaction mixture. With γ-substituted allylic indium sesquibromides, the coupling occurred selectively at the γ-carbon (entries 2-4). Substituents at the C4-carbon of allenol showed no significant