Coupling Reaction of Highly Reactive Borates and Substrates with sterichindrance

高反应性硼酸盐与底物的偶联反应

基本信息

批准号：
10650843
负责人：
KOBAYASHI Yuichi
金额：
$ 2.05万
依托单位：
Tokyo Institute of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 2000
项目状态：
已结题

项目摘要

Recently, we have developed a new type of coupling reagent that allows participation of secondary allylic esters as substrates, thus indicating a high reactivity of the reagents. In this project, we have investigated coupling reaction of these reagents and substrates which have not been investigated due to steric hinderance, and the fruitful results are presented below.(1) Coupling reaction of 8-acetoxy-octalone-Δ^<1(9)>-2 and phenylborates in the presence of a nickel catalyst proceeded stereo- and regioselectively to afford 8-phenyloctalone-Δ^<1(9)>-2 in good yield. Interestingly, the observed stereochemistry is independent of that of the starting allylic substrate. This outcome is not consistent with the well-established mechanism, and we are proposing another one in which the nickel enolates play a central role.(2) Coupling reaction of cyclohexenyl acetates proceeds through the π-allylnickel species which possesses a symmetrical plane and hence presence of a chiral center in a reage … More nt is expected to provide a bias for the regioselectivity. This possibility was examined with arylborates with a chiral substituent at the ortho position to result in a production of one diastereomer highly selectively.(3) Although cis 1-bromoalkenes with a silyloxy substituent at 3-position is less reactive substrates toward the coupling reaction due to the steric hindrance, alkenylborates was found to furnish coupling products efficiently. The reaction was successfully applied in a total synthesis of 10,11-dihydroleukotriene B_4 and the related molecules.(4) With the above reaction, determination of the stereochemistry of natural korormicin was investigated. In practice, possible four diastereoisomers were synthesized stereoselectively by using this coupling reaction, and comparison of their specific rotations with that of the natural one revealed that the (5S,3'R,9'S,10'R)-isomer is unambiguously to be the natural korormicin.(5) Aldol reaction at the α dash position of γ-alkeny-α, β-unsaturated cyclopentenones, easily prepared from the coupling product of 4-cyclopentene-1,3-diol and borates, is investigated and applied to synthesis of Δ^7-PGA_1 methy ester. Less

最近，我们开发了一种新型的耦合试剂，该试剂允许将次级近酯作为底物参与，从而表明试剂的反应性很高。在这个项目中，我们已经投入了这些试剂和底物的耦合反应，这些反应尚未由于空间的障碍而进行了研究，下面介绍了富有成果的结果。（1）8-乙酰氧基-Octalone-δ^<1（9）> - 2的偶联反应在镍含量的情况下进行了镍含量，并在镍级稳定的情况下进行了调节型的Storeo-condereo condereo condereo-condereo condereo-condereo condereo，并8-苯二氧甲烯-Δ^<1（9）> -2的产量良好。有趣的是，观察到的立体化学独立于起始的Allicular底物。该结果与公认的机制不一致，我们提出了另一种镍烯醇发挥核心作用的结果。（2）环己烯基乙酸酯的偶联反应通过具有对称的π-甲基尼克物种进行。平面并因此在Reege中存在手性中心……预计会有更多的NT为调节选择性提供偏见。用芳基硼酸盐和手性亚能力在矫正位置检查了这种可能性，从而高度选择地产生了一种钻石剂。（3）尽管在3位置下具有较小的反应性底物对cIS 1-溴烯烃在3位时具有较小的反应性底物对构型的反应反应，因此对稳定性的反应造成了反应，因此对稳定性的反应产生了反应。在总合成中应用了10,11-二氢苯甲酸B_4和相关分子。（4）与上述反应相关的分子，研究了天然巨质蛋白的立体化学的测定。在实践中，通过使用这种耦合反应对可能的四个可能的四个非映异构体进行了立体选择，并将其特定旋转与自然旋转进行比较，表明（5s，3'r，9's，10'r） - 异构体是明确的，是天然的乌尔摩素蛋白。细胞环烯酮很容易从4-胞烯烯-1,3-二醇和硼酸盐的耦合产物中制备，并应用于Δ^7-PGA_1甲基酯的合成中。较少的