Developemt of Asymmetric Carbanion Rearrangements with High Stereoselection

高立体选择不对称碳负离子重排的研究

• 批准号: 60470092
• 负责人: NAKAI Takeshi
• 金额: $ 2.82万
• 依托单位: Tokyo Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1985
• 资助国家: 日本
• 起止时间: 1985 至 1986
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-60470092/
• 关键词: Asymmetric Synthesis; [2,3]-Wittig Rearrangement; Chiral Enolate; <alpha> -Hydroxy Carboxylic Acid; 8-Phenylmenthol; Diastereofacial Selection; α-ヒドロキシカルボン酸

The main results of this project are summarized as follows.(1) Asymmetric [2,3]-Wittig rearrangement involving chiral lithium and potassium azaenolate termini generated from chiral 2-oxazolines have been investigated. We found that these rearrangements provided relatively high optical yields (78-95% ee). During these studies, we have observed interesting influences of the countercation (Li vs. K) and their complexation with a crown ether. Furthermore, the asymmetric reaction has successfully been applied to the chiral synthesis of unnatural verrucarinolactone.(2) Asymmetric [2,3]-Wittig rearrangement involving chiral amide Li- and Zr( <IV> )-enolate termini generated from the prolinol- and valinol-derived amide systems has been studied. Unfortunately, these asymmetric variants have been found to provide only moderate levels of asymmetric induction. Interestingly, however, the Zr-enolate variant has been shown to the opposite sense of diastereofacial selection to that of the Li-enolate … More counterpart.(3) Asymmetric [2,3]-Wittig rearrangement involving chiral ester enolate termini generated from the 8-phenylmenthol-derived chiral ester system has been investigated in details. First, we have found that the Li-enolate rearrangement provides an extremely high optical yields (>95% ee) along with a high erythro-selectivity (>90%). Thus, this type of asymmetric rearrangement offers an efficient method for chiral synthesis of <alpha> -hydroxy- <beta> -alkyl carboxylic acid derivatives. Its efficiency has been demonstrated within the simple chiral synthesis of verrucarinolactone. Second, the rearrangement involving Ti( <IV> )- and Sn( <IV> )-enolates generated from the silyl enol ether via transmetalation has been found to exhibit very low levels of asymmetric induction. Third, the rearrangement involving Zr( <IV> )-enolate generated from the Li-enolate via transmetalation, by contrast, provides a high optical yield comparable to that of the Li-enolate counterpart.On the basis of these results described above, we have discussed and elucidated the structures of the metal enolates involved in the [2,3]-Wittig rearrangements. Less

该项目的主要结果总结如下：(1)研究了手性2-恶唑啉产生的手性锂和氮杂烯酸钾末端的不对称[2,3]-Wittig重排，我们发现这些重排提供了相对较高的光学产率。 (78-95% ee) 在这些研究中，我们观察到抗衡阳离子（Li 与 K）及其与冠醚的络合的有趣影响。已成功应用于非天然verrucarinolactone的手性合成。(2)涉及由脯氨醇和缬氨醇衍生的酰胺系统产生的手性酰胺Li-和Zr(<IV>)-烯醇化物末端的不对称[2,3]-Wittig重排不幸的是，已发现这些不对称变体仅提供中等水平的隐式不对称诱导，然而，Zr-烯醇化物变体已显示出相反的意义。 (3) 涉及由 8-苯基薄荷醇衍生的手性酯系统产生的手性酯烯醇化物末端的不对称 [2,3]-Wittig 重排首先，我们进行了详细研究。发现锂烯醇重排提供了极高的光学产率（> 95% ee）以及高红细胞选择性（> 90%）。这种类型的不对称重排为手性合成<α>-羟基-<β>-烷基羧酸衍生物提供了一种有效的方法，其效率已在verrucarinolactone 的简单手性合成中得到证明。 > )-和Sn( <IV> )-烯醇化物通过金属转移由甲硅烷基烯醇醚生成，已发现表现出非常低水平的不对称诱导第三，涉及重排。相比之下，通过金属转移从Li-烯醇化物生成的Zr(<IV>)-烯醇化物提供了与Li-烯醇化物对应物相当的高光学产率。在上述结果的基础上，我们讨论并阐明了参与 [2,3]-Wittig 重排的金属烯醇化物的结构。

项目成果

Osamu Takahashi: Chemistry Letters. 69-72 (1987)

高桥修：化学快报。

Takeshi Nakai: Chemical Reviews. 86. 885-902 (1986)

中井武：化学评论。

Koichi Mikami: Chemistry Letters. 1729-1732 (1985)

三上浩一：化学快报。

中井武: PETROTECH. 10. 58-64 (1987)

中井武：《石油技术》。10. 58-64 (1987)

Koichi Mikami: Tetrahedron Letters. 25. 6011-6014 (1984)

三上浩一：四面体字母。