Revealing the mechanisms of titanium-catalyzed umpolung reactions by a combined experimental and theoretical approach

通过实验和理论相结合的方法揭示钛催化反极化反应的机理

• 批准号: 275167197
• 负责人: Professor Dr. Jan Streuff
• 金额: --
• 依托单位: Institutionen för kemi
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2018-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/275167197?language=en
• 关键词: Revealing; mechanisms; titanium; catalyzed; umpolung

Titanium(III)-catalyzed reductive umpolung-reactions provide an elegant access to carbon-carbon bonds that cannot be formed in a direct fashion by other methods. Based on our previous works on ketone-nitrile and enone-ennitrile couplings, we will investigate the mechanisms of such reactions by a combination of experimental works and DFT-calculations. The main goal is to perform and understand the individual parts of the catalytic cycles and to develop models for the key-steps, especially the C-C bond forming events. The role of cationic intermediates and the participation of a second titanium(III)-species will be investigated in detail. In addition, it is our aim to provide an explanation for the high selectivities that we observed in our previously published enantioselective ketonitrile cyclization reaction. First results are provided that support the feasibility of each individual part of the research program. The conclusions from this project will have a major impact on the development of new reactions and catalyst generations in this field. They will provide a general understanding of reductive umpolung reactions and greatly facilitate future investigations in this research area.

钛（III）催化的还原性umpolung反应提供了一个优雅的碳-碳键，不能通过其他方法直接形成。基于我们以前对酮-腈和烯酮-腈偶联反应的研究，我们将通过实验和DFT计算相结合的方法来研究这些反应的机理。主要目标是执行和理解催化循环的各个部分，并开发关键步骤的模型，特别是C-C键形成事件。阳离子中间体的作用和参与的第二钛（III）物种将详细研究。此外，我们的目的是提供一个解释的高选择性，我们观察到在我们以前发表的对映选择性酮腈环化反应。第一个结果提供了支持研究计划的每个单独的部分的可行性。该项目的结论将对该领域新反应和催化剂代的开发产生重大影响。他们将提供一个一般性的了解还原umpolung反应，并大大促进在这一研究领域的未来调查。

项目成果

Understanding titanium-catalysed radical-radical reactions: a DFT study unravels the complex kinetics of ketone-nitrile couplings.

• DOI: 10.1039/c8dt00643a
• 发表时间: 2018-04
• 期刊: Dalton transactions
• 影响因子: 4
• 作者: Jan Streuff;D. Himmel;S. Younas

Mechanism of the Ti(III)-Catalyzed Acyloin-Type Umpolung: A Catalyst-Controlled Radical Reaction.

Ti(III) 催化的偶姻型逆转的机制：催化剂控制的自由基反应

• DOI: 10.1021/jacs.5b09223
• 发表时间: 2015
• 期刊: Journal of the American Chemical Society
• 影响因子: 15
• 作者: J. Streuff;M. Feurer;G. Frey;A. Steffani;S. Kacprzak;J. Weweler;L. H. Leijendekker;D. Kratzert;D. A. Plattner
• 通讯作者: D. A. Plattner