Cationic NHC‐Phosphine Iridium Complexes: Highly Active Catalysts for Base‐Free Hydrogenation of Ketones
作者:Xu Quan、Sutthichat Kerdphon、Bram B. C. Peters、Janjira Rujirawanich、Suppachai Krajangsri、Jira Jongcharoenkamol、Pher G. Andersson
DOI:10.1002/chem.202002811
日期:2020.10.15
evaluated in the hydrogenation of ketones. Reported catalytic systems require base additives and, if excluded, need elevated temperature or high pressure of hydrogen gas to achieve satisfactory reactivity. The developed catalysts showed extremely high reactivity and good enantioselectivity under base‐free and mild conditions. In the presence of 1 mol % catalyst under 1 bar hydrogen pressure at room
合成了新型双齿N-杂环卡宾-膦铱络合物,并在酮的氢化反应中进行了评估。报道的催化系统需要碱添加剂,并且如果不包括在内,则需要高温或高压氢气才能达到令人满意的反应性。在无碱和温和条件下,开发的催化剂显示出极高的反应活性和良好的对映选择性。在室温下,在1 bar氢气压力下,在1 mol%催化剂的存在下,氢化反应在30分钟内完成,给出最高96% ee。同样,这种高反应性是在无添加剂的条件下实现的。力学实验表明,氢气的球囊压力足以通过减少和消除1,5-环辛二烯配体来形成活化物种。预活化的催化剂能够在5分钟内氢化苯乙酮,转化率为89%。