New Development of Asymmetric Olefination

开展了不对称烯化反应的科研工作，其研究计划在资助申请表中进行了详细说明，取得了以下成果。将多种双酮底物应用于HWE型轴向手性膦酸类试剂的不对称烯化反应中，证实了该试剂的总体有效性。其中，通过化学转化和X射线晶体分析确定了产物的绝对立体结构。考虑了反应的机理，提出了以阴离子对酮类底物的亲核攻击为速率控制步骤的动力学控制机理。利用格氏试剂的模型实验估算了亲核攻击的方向。通过这些模型试验和计算，结果表明，该方向是由轨道控制因素决定的，而不是…比立体的更多。开发了一种实用、高效的基于C-C键形成的合成方法，该方法以BHT酯为当量烯酮。与已知的方法相比，新的反应体系提供了更高的化学和光学产率。本研究表明，即使是简单的酚酯类化合物也可以作为烯类化合物的前体，并以令人满意的化学和光学产率得到相应的光学活性烯丙酸酯类化合物。设计并合成了具有光学活性的邻对称双酮，并研究了基于羰基识别的分子内不对称HWE反应。以令人满意的化学和光学产率，成功地构建了含有季碳和四取代烯烃部分的光学活性环系。X-射线晶体分析明确了部分产物的绝对立体结构。以双烯和芳烃的对称金属(Fe和Cr)络合物为底物进行不对称烯化反应，得到了相应的平面手性烯烃产物，得到了满意的化学和光学产物。对外消旋酮的动力学拆分进行了初步的实验研究。在一些氨基酸衍生物的情况下，烯烃产品的光学产率很高，这些广泛的研究正在进行中。较少

The scientific research works of the asymmeric olefination, the research planning of which are described in the grant application form in detail, were performed and the following results are obtained.1. A variety of diketonic substrates were applied to the asymmetric olefination utilizing the axially chiral phosphonate reagent of the HWE type, and the general effectiveness of the reagent was positively proven. Therein, the absolute stereostructure of the products was determined by chemical transformations as well as the X-ray crystal analyses.2. The mechanistic aspects of the reaction was considered, where the kinetically controlled mechanism of the nucleophilic attack of the anion to the ketonic substrate as the rate determining step was proposed. The direction of the nucleophilic attack was estimated by using model experiments of thc Grignard reagents. From these model experiments and the calculation, it turned out that the direction was governed by the orbital control factors rather … More than the steric ones.3. A practical and efficient synthetic method based on the C-C bond formation was developed by using the BHT esters as the ketene equivalent. The new reaction system afforded the higher chemical and optical yield than the previously known method. In this study, it was shown that even the simple phenolic esters can be the precursor for the ketenes and gave the corresponding optically active allenic esters in satisfactory chemical and optical yield.4. The o-symmetrical diketones bearing the optically active phosphonate moiety were designed and prepared and intramolecular asymmetric HWE reaction based on the discrimination of the carbonyls was investigated. The optically active ring system having quaternary carbon and tetra-substituted olefinic moiety was successfully constructed in satisfactory chemical and optical yield. The absolute stereostructure of some of the products was unambiguously elucidated by the X-ray crystal analysis.5. The symmetrical metal (Fe and Cr) complexes of diene and arenes were applied as the substrates to the asymmetric olefination, and the corresponding olefinic products of the planar chirality was obtained in satisfactory chemical and optical yield.6. The preliminary experiments of the kinetic resolution of the racemic ketones was investigated. In the case of some amino acid derivatives, the high optical yield of the olefinic products was achieved and these extensive investigations are in progress. Less