Department of Chemistry, University of Houston, 3585 Cullen Boulevard, Room 112, Houston, TX 77204-5003, Texas.
Chemistry. 2021 Dec 15;27(70):17601-17608. doi: 10.1002/chem.202102627. Epub 2021 Oct 29.
The direct replacement of sp C-H bonds with simple amine units (-NH ) remains synthetically challenging, although primary aliphatic amines are ubiquitous in medicinal chemistry and natural product synthesis. We report a mild and selective protocol for preparing primary and secondary aliphatic amines in a single pot, based on intermolecular sp C-H imination. The first C-H imination of diverse alkanes, this method shows useful site-selectivity within substrates bearing multiple sp C-H bonds. Furthermore, this reaction tolerates polar functional groups relevant for complex molecule synthesis, highlighted in the synthesis of amine pharmaceuticals and amination of natural products. We characterize a unique C-H imination mechanism based on radical rebound to an iminyl radical, supported by kinetic isotope effects, stereoablation, resubmission, and computational modeling. This work constitutes a selective method for complex amine synthesis and a new mechanistic platform for C-H amination.
sp C-H 键与简单胺基单元(-NH )的直接取代在合成上仍然具有挑战性,尽管伯脂肪胺在药物化学和天然产物合成中无处不在。我们报告了一种温和且选择性的方法,可在一锅反应中制备伯和仲脂肪胺,基于分子间 sp C-H 亚胺化反应。该方法首次实现了各种烷烃的 C-H 亚胺化,在具有多个 sp C-H 键的底物中显示出有用的位点选择性。此外,该反应还能耐受与复杂分子合成相关的极性官能团,这在胺类药物的合成和天然产物的胺化中得到了突出体现。我们基于自由基向亚胺基自由基的回弹,通过动力学同位素效应、立体消除、重新引入和计算建模,对独特的 C-H 亚胺化机制进行了表征。这项工作为复杂胺类的合成提供了一种选择性方法,并为 C-H 胺化提供了一个新的机制平台。