镍络合物催化条件下2,2′-联吡啶的偶联合成

Synthesis of 2,2′-Bipyridine through Catalitic Coupling Reaction ofα-Brompyridine Using Nickel Complex

在制备联吡啶的偶联反应中 ,镍化合物和三苯基膦通常是以化学计量参与反应 .我们在对Tiecco报道的偶联反应进行研究的过程中发现 ,这一反应可以在催化条件下进行 .这一改进主要基于投料顺序的改变 ,充分利用零价镍当场 (insitu)生成时的高活性 .将氯化镍、三苯基膦、2 溴吡啶先溶于DMF中 ,然后在 5 0℃时加入锌粉 ,催化偶联生成联吡啶 ,可以获得满意的收率 .同时对三种镍化合物的反应活性作了比较 ,以NiCl2 ·6H2 O活性最高 .

Ni compounds and PPh 3 were usually used in stoichiometric amounts for the synthesis of bipyridine via coupling reaction. This reaction procedure was improved by using only catalytical amounts of nickel and PPh 3 in the presence of zinc. This modification was mainly based on the changes of reaction addition order which could sufficiently utilize the Ni(0) generated in situ. Bipyridine can be synthesized by this catalytical procedure with satisfactory yield. The activity of three kinds of Ni complexes was compared in the reaction, and NiCl 2·6H 2O represented the highest activity.