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. [2+2]羰基化合物与酮的环加成反应[2+2]的环加成反应通过使用一些阳离子组8-10的过渡金属配合物作为催化剂，其中Palladiun和Platinum Complives中有良好的完善。发现该催化活性不仅受到金属中心和配体的极大影响，而且还受到柜台阴离子的影响。发现通过手性配体进行不对称诱导的尝试失败了，但发现源自替代的binols的四烷基硼酸酯，可作为非对称反应中的手性识别元件。 α，β-不饱和的羰基化合物，在条件下由len重排的环加成产生的4- vinyloxetan-2-酮，得到3,6-二二氢-2H-Pyran-2-酮。这是检查了一系列α，β，不饱和醛和酮与酮的反应，以推断重排的起源。发现如果4位在4位处或乙烯基部分的2位在环载条中产生烷基取代基的4-伏氧二烯-2-酮，则会发生反应。基于观察结果，提出了一种复制机制，其中包括由4- vinyloxetan-2-one作为中间体的C（4）-0键的杂裂裂解产生的。 Asymmetric induction with up to 57% 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从充电到芳族化合物和有机硅烷，这可能会导致一种替代方法，以便将来从烯烃和co_2制备oxetan-2-酮。