Nickel-Catalyzed Coupling Reactions of Alkyl Electrophiles, Including Unactivated Tertiary Halides, To Generate Carbon–Boron Bonds
作者:Alexander S. Dudnik、Gregory C. Fu
DOI:10.1021/ja304068t
日期:2012.6.27
examples of coupling reactions of unactivated tertiary alkyl electrophiles, as well as our first success with nickel-catalyzed couplings that generate bonds other than C-C bonds. Specifically, we have determined that this catalyst accomplishes Miyaura-type borylations of unactivated tertiary, secondary, and primary alkyl halides with diboron reagents to furnish alkylboronates, a family of compounds with substantial
通过使用NiBr(2)·二甘醇二甲醚原位形成的催化剂和pybox配体(两者均可商购),我们实现了未活化叔烷基亲电试剂偶联反应的第一个实例,并取得了首次成功镍催化偶联产生除 CC 键以外的键。具体来说,我们已经确定,这种催化剂在温和条件下完成了未活化的叔、仲和伯烷基卤化物与二硼试剂的宫浦型硼酸化反应,以提供烷基硼酸酯,这是一个具有实质性(并扩大)效用的化合物家族;事实上,叔烷基溴的 umpolung 硼酸化可以在低至 -10 °C 的温度下实现。该方法表现出良好的官能团兼容性和区域特异性,这两者都可能是合成烷基硼酸酯的传统方法的问题。与看似相关的镍催化 CC 键形成过程相反,在这种镍催化的 CB 键形成反应中,叔卤化物比仲卤化物或伯卤化物更具反应性;鉴于两种转化都可能遵循氧化加成的内球电子转移途径,这种差异尤其值得注意。