Department of Applied Chemistry, School of Engineering, The University of Tokyo, Tokyo, Japan.
J Org Chem. 2011 Jun 3;76(11):4606-10. doi: 10.1021/jo2004956. Epub 2011 May 2.
In the presence of an easily prepared supported ruthenium hydroxide catalyst, Ru(OH)(x)/Al(2)O(3), various kinds of structurally diverse primary azides including benzylic, allylic, and aliphatic ones could be converted into the corresponding nitriles in moderate to high yields (13 examples, 65-94% yields). The gram-scale (1 g) transformation of benzyl azide efficiently proceeded to give benzonitrile (0.7 g, 90% yield) without any decrease in the performance in comparison with the small-scale (0.5 mmol) transformation. The catalysis was truly heterogeneous, and the retrieved catalyst could be reused for the transformation of benzyl azide without an appreciable loss of its high performance. The present transformation of primary azides to nitriles likely proceeds via sequential reactions of imide formation, followed by dehydrogenation (β-elimination) to produce the corresponding nitriles. The Ru(OH)(x)/Al(2)O(3) catalyst could be further employed for synthesis of amides in water through the transformation of primary azides (benzylic and aliphatic ones) to nitriles, followed by sequent hydration of the nitriles formed. Additionally, direct one-pot synthesis from alkyl halides and TBAN(3) (TBA = tetra-n-butylammonium) could be realized with Ru(OH)(x)/Al(2)O(3), giving the corresponding nitriles in moderate to high yields (10 examples, 64-84% yields).
在易于制备的负载型氢氧化钌催化剂 Ru(OH)(x)/Al(2)O(3)的存在下，各种结构多样的伯叠氮化物，包括苄基、烯丙基和脂肪族叠氮化物，可以中等至高产率（13 个实例，65-94%产率）转化为相应的腈。克级（1 g）的苄基叠氮化物的转化可以有效地进行，而无需任何性能下降，即可得到苯甲腈（0.7 g，90%产率），与小规模（0.5 mmol）转化相比。该催化反应是真正的多相反应，回收的催化剂可用于苄基叠氮化物的转化，而不会明显降低其高性能。伯叠氮化物到腈的这种转化可能通过酰胺形成的顺序反应进行，然后通过脱氢（β-消除）产生相应的腈。Ru(OH)(x)/Al(2)O(3)催化剂还可以通过伯叠氮化物（苄基和脂肪族）转化为腈，然后腈形成后进行连续水合反应，进一步用于水相中酰胺的合成。此外，通过 Ru(OH)(x)/Al(2)O(3）可以实现从烷基卤化物和 TBAN(3)（TBA = 四正丁基铵）的直接一锅法合成，中等至高产率（10 个实例，64-84%产率）得到相应的腈。
