Richardson Georgia M, Rajeshkumar Thayalan, Burke Finlay M, Cameron Scott A, Nicholls Brooke D, Harvey Joanne E, Keyzers Robert A, Butler Tane, Granville Simon, Liu Lujia, Langley Julien, Lim Li F, Cox Nicholas, Chilton Nicholas F, Hicks Jamie, Davis Nathaniel J L K, Maron Laurent, Anker Mathew D
School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington, New Zealand.
Laboratory of Physics and Chemistry of Nano-Objects (UMR 5215), Institut National des Sciences Appliquées, Université Toulouse III-Paul Sabatier, Centre National de la Recherche Scientifique and Université de Toulouse, Toulouse, France.
Nat Chem. 2025 Jan;17(1):20-28. doi: 10.1038/s41557-024-01688-6. Epub 2025 Jan 3.
Benzene reduction by molecular complexes remains an important synthetic challenge, requiring harsh reaction conditions involving group I metals. Reductions of benzene, to date, typically result in a loss of aromaticity, although the benzene tetra-anion, a 10π-electron system, has been calculated to be stable and aromatic. Due to the lack of sufficiently potent reductants, four-electron reduction of benzene usually requires the use of group I metals. Here we demonstrate the four-electron reduction of benzene and some of its derivatives using a samarium(II) alkyl reagent, with no requirement for group I metals. Whereas organosamarium(II) typically reacts through one-electron processes, the compounds reported here feature a rare two-electron process. Combined experimental and computational results implicate a transient samarium(I) intermediate involved in this reduction process, which ultimately provides the benzene tetra-anion. The remarkably strong reducing power of this samarium(II) alkyl implies a rich reactivity, providing scope for its application as a reducing agent.
通过分子配合物还原苯仍然是一个重要的合成挑战，需要涉及碱金属的苛刻反应条件。迄今为止，苯的还原通常会导致芳香性丧失，尽管据计算苯四价阴离子（一种10π电子体系）是稳定且具有芳香性的。由于缺乏足够强的还原剂，苯的四电子还原通常需要使用碱金属。在此，我们展示了使用二价钐烷基试剂对苯及其一些衍生物进行四电子还原，无需使用碱金属。虽然有机二价钐通常通过单电子过程反应，但本文报道的化合物具有罕见的双电子过程。结合实验和计算结果表明，该还原过程涉及一个瞬态一价钐中间体，最终生成苯四价阴离子。这种二价钐烷基的极强还原能力意味着其具有丰富的反应活性，为其作为还原剂的应用提供了空间。
