Hydrogenation of unsaturated bonds is dominated by transition metal catalysis. Compared with transition metals, the use of other metals is less explored, especially so for the s-block elements despite their ready availability and low cost. Here, we show that group 2 metal amides (M[N(SiMe₃)₂]₂, M = Mg, Ca, Sr, Ba) unexpectedly catalyse the hydrogenation of aldimines with H₂ at 80 °C and a remarkably low H₂ pressure of 1–6 bar. Conversion rates increase with metal size: Mg < Ca < Sr < Ba (for Ba, quantitative conversion is reached within 15 min). The key to this catalysis is the unanticipated formation of metal hydride species by deprotonation of H₂ (pK _a ≈ 49) with a weak base M[N(SiMe₃)₂]₂ (HN(SiMe₃)₂: pK _a ≈ 25.8). Density functional theory calculations suggest that the most favourable pathway indeed involves metal hydride intermediates. The efficient alkaline earth metal-catalysed hydrogenation of imines with molecular hydrogen at remarkably low pressure provides an attractive alternative to transition metal catalysis.

不饱和键的氢化主要由过渡金属催化。与过渡金属相比，较少探索使用其他金属，特别是对于S嵌段元素而言，尽管它们易于获得且成本低廉。在这里，我们表明第2组金属酰胺（M [N（SiMe ₃）₂ ] ₂，M = Mg，Ca，Sr，Ba）出乎意料地在80°C和低H ₂的条件下催化了Aldimines与H ₂的氢化。压力为1–6 bar。转化率随金属尺寸而增加：Mg <Ca <Sr <Ba（对于Ba，在15分钟内达到定量转化）。催化的关键是H ₂（pķ _一个 ≈49）用弱碱M [N（森达₃）₂ ] ₂（HN（森达₃）₂：P ķ _一个 ≈25.8）。密度泛函理论计算表明，最有利的途径确实涉及金属氢化物中间体。在非常低的压力下，有效的碱土金属催化的亚胺与分子氢的加氢为过渡金属催化提供了有吸引力的替代方法。