钯催化炔基溴与格氏试剂的交叉偶联反应合成1,2-二取代炔烃

Synthesis of 1,2-disubstituted alkynes via Palladium-catalyzed cross-coupling reaction of alkynyl bromide with Grignard reagent

炔烃是一类重要的结构单元,广泛应用于药物化学、有机合成及材料科学中.报道了在室温条件下,以四氢呋喃为溶剂,炔基溴(1mmol)与格氏试剂(1.3mmol)在Pd(OAc)_2(3 mol%)/Ph_3P(9 mol%)催化下进行偶联反应,以中等至较好的收率得到了多种1,2-二取代炔烃类化合物.该反应体系对于带不同种类的功能基团的芳基格氏试剂及烷基格氏试剂均有很好的催化活性,而且对于大位阻的α-萘基格氏试剂也有较好的催化效果.该反应体系简单、催化效率高,不需要其它共催化剂.此外,根据实验结果,提出了Pd(OAc)_2催化炔基溴与格氏试剂偶联反应的可能机理.

Alkynes are important structural motifs utilized in organic synthesis,pharmaceutical chemistry,and material science. In the present study,the cross-coupling reaction of alkynyl bromide（1 mmol） with Grignard reagent（1. 3 mmol） mediated by Pd（OAc）_2（3 mol%）and Ph_3P（9 mol%） in THF could provide 1,2-disubstituted acetylenes in moderate to good yield at room temperature. This reaction system has good catalytic activity for aryl Grignard reagents with variety of functional groups and alkyl Grignard reagents,and for the alpha naphthyl Grignard reagent also has good catalytic activity. The reaction system is simple and of high catalytic efficiency,especially,no other co-catalysts are needed. Based on established palladium chemistry,a mechanism to account for the formation of products is proposed.