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反应为碳碳键提供了优雅的访问，而其他方法无法直接形成碳碳键。基于我们以前关于酮硝基和Enone-Ennitrile耦合的作品，我们将通过实验工作和DFT计算的结合来研究此类反应的机制。主要目标是执行和理解催化循环的各个部分，并为关键步骤，尤其是C-C键形成事件开发模型。将详细研究阳离子中间体的作用和第二钛（III）种类的参与。此外，我们的目的是为我们在先前发表的对映选择性氯硝基环化反应中观察到的高选择性提供解释。提供了支持研究计划每个部分的可行性的第一个结果。该项目的结论将对该领域的新反应和催化剂几代的发展产生重大影响。他们将对还原性的Umpolung反应提供一般的理解，并极大地促进了该研究领域的未来研究。

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