不用铁粉，钯碳，Raney Ni，温和还原硝基制备胺！

分子科学 2024-02-20 08:12

Raney Ni加氢，但是当分子内存在对加氢敏感的官能团，如：卤素（Cl, Br and I; F 对加氢不敏感），双键，三键时，我们不得不采用其他方法， 最为经典的要数在酸性条件下的铁粉的还原。含硫的还原剂如硫化钠、硫化胺、亚硫酸氢钠、连二亚硫酸钠等是在碱性或中性条件下选用的还原剂. 此类还原剂的特点是能使多硝基化合物中部分硝基还原为氨基。

2015年，意大利的M. Benaglia团队报道了HSiCl3作为还原剂在温和条件下将硝基还原为胺。该方法对很多敏感官能团（如苄基，氰基，卤素）兼容性良好。此方法芳香硝基化合物和脂肪硝基化合物同样适用。

对于一些手性硝基化合物，反应后也能保持很好光学活性。

反应机理

HSiCl3和三级胺反应生成SiCl2或[SiCl3]-

两种可能的机理：

反应操作

General procedure and reaction conditions optimization：In a round bottomed flask the nitro-compound (0.7 mmol) and the tertiary amine (3.5 mmol) were dissolved into the dry solvent (5 mL) under magnetic stirring and nitrogen atmosphere. A solution of freshly distilled HSiCl3 (2.5 mmol) in 2 mL of dry solvent was prepared apart, and it was added drop-wise to the first solution over 10 minutes at 0 °C. After stirring the reaction mixture for 18 h, 5 mL of a saturated solution of NaHCO3 was added drop-wise and the biphasic mixture was allowed to stir for 30 min. The crude mixture was extracted with ethyl acetate, dried over Na2SO4, filtered and then dried under reduced pressure to afford the crude product.

 

参考资料：

Metal-Free Reduction of Aromatic and Aliphatic Nitro Compounds to Amines: A HSiCl3?Mediated Reaction of Wide General Applicability, Org. Lett. 2015, 17, 3941−3943.