Department of Chemistry, Aarhus University, 8000, Aarhus, Denmark.
Chemistry. 2018 Oct 1;24(55):14844-14848. doi: 10.1002/chem.201803506. Epub 2018 Sep 10.
A novel strategy for the direct enantioselective oxidative homocoupling of α-branched aldehydes is presented. The methodology employs open-shell intermediates for the construction of chiral 1,4-dialdehydes by forming a carbon-carbon bond connecting two quaternary stereogenic centers in good yields and excellent stereoselectivities for electron-rich aromatic aldehydes. The 1,4-dialdehydes were transformed into synthetically valuable chiral pyrrolidines. Experimental mechanistic investigations based on competition experiments combined with computational studies indicate that the reaction proceeds through a radical cation intermediate and that reactivity and stereoselectivity follow different trends.
本文提出了一种新颖的手性α-支链醛直接对映选择性氧化偶联策略。该方法通过形成连接两个季碳立体中心的碳-碳键，利用开壳中间体构建手性 1,4-二醛，对富电子芳香醛具有良好的收率和优异的对映选择性。1,4-二醛被转化为具有合成价值的手性吡咯烷。基于竞争实验与计算研究相结合的实验机理研究表明，反应通过自由基阳离子中间体进行，反应性和对映选择性遵循不同的趋势。
