Development of Cationic Transition Metal Complex-Catalyzed Asymmetric [2+2] Cycloaddition Reaction

阳离子过渡金属配合物催化不对称[2 2]环加成反应的研究进展

基本信息

批准号：
13650908
负责人：
HATTORI Tetsutaro
金额：
$ 2.3万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

1.[2+2] Cycloaddition reaction of carbonyl compounds with ketene The [2+2] cycloaddition reaction was examined by using some cationic group 8-10 transition metal complexes as the catalysts, among which palladiun and platinum complexes showed good perfonnance. It was found that the catalytic activity was greatly affected not only by the metal center and the ligand but also by the counter anion. Attempts on asymmetric induction by using chiral ligands failed but chiral counterions, tetraalkoxy borates derived from substituted BINOLs, were found to serve as a chirality-recognizing element in the asymmetric reaction.2.Tandem [242] cycloaddition-allylic rearrangement or α,β-unsaturatead carbonyl compounds with ketene In the reaction of α,β-unsaturated carbonyl compounds, 4-vinyloxetan-2-ones generated by the cycloaddition oflen rearrange under the conditions to give 3,6-dihydro-2H-pyran-2-ones. Thus, the reaction of a series of α,β-unsaturated aldehydes and ketones with ketene was examined to deduce the origin of the rearrangement. It was found that the reaction occurs if 4-vinyloxetan-2-ones bearing an alkyl substituent at the 4-position or at the 2-position of the vinyl moiety are generated in the cycloaddition. Based on the observations, a reacfion mechanism was proposed, which includes a zwitterion generated by heterolytic cleavage of the C(4)-0 bond of the 4-vinyloxetan-2-one as an intermediate. Asymmetric induction with up to 57% de has been achieved by using α,β-unsaturated aldehydes bearing an asymmetric carbon center at the β-position.3.Activation of CO_2 by Lewis acids and its chemical fixation to carbon-carbon double bonds As an extension of this research project, a possibility was examined to activate C0_2 by aluminum-based Lewis acids and fix it electrophilically to aromatic compounds and organosilanes, which might lead to an alternative method to prepare oxetan-2-ones from olefins and CO_2 in the future.

1.羰基化合物与乙烯酮的[2+2]环加成反应以一些阳离子基团8-10过渡金属配合物为催化剂考察了[2+2]环加成反应，其中钯和铂配合物表现出良好的性能。发现催化活性不仅受到金属中心和配体的影响，而且还受到抗衡阴离子的影响，尝试使用手性进行不对称诱导。配体失败，但手性抗衡离子，衍生自取代联醇的四烷氧基硼酸盐，被发现在不对称反应中充当手性识别元素。2.串联[242]环加成-烯丙基重排或与烯酮的α，β-不饱和羰基化合物α,β-不饱和羰基化合物、4-乙烯基氧杂环丁烷-2-酮的环加成反应在该条件下经常会重排生成3,6-二氢-2H-吡喃-2-酮。因此，研究了一系列α,β-不饱和醛和酮与乙烯酮的反应，以推断重排的起源。发现如果在乙烯基部分的4位或2位带有烷基取代基的4-乙烯基氧杂环丁烷-2-酮在基于观察结果，提出了一种反应机制，其中包括通过 4-vinyloxetan-2-one 的 C(4)-0 键异解裂解生成的两性离子作为最多 57 的不对称诱导物。利用β位带有不对称碳中心的α,β-不饱和醛实现了%de。3.Lewis酸对CO_2的活化及其化学固定作为该研究项目的延伸，研究了通过铝基路易斯酸活化CO_2并将其亲电固定到芳香族化合物和有机硅烷上的可能性，这可能会导致制备oxetan-2-的替代方法未来来自烯烃和CO_2的。