Radical Mechanisms in the Reaction of Organic Halides with Diiminepyridine Cobalt Complexes
作者:Di Zhu、Ilia Korobkov、Peter H. M. Budzelaar
DOI:10.1021/om300182c
日期:2012.5.28
LCo(N2) reacts with many alkyl and aryl halides RX, including aryl chlorides, to give a mixture of LCoR and LCoX in a halogen atom abstraction mechanism. Intermediacy of free alkyl and aryl radicals is confirmed by the ring-opening of cyclopropylmethyl to crotyl, and the rearrangement of 2,4,6-tBu3C6H2 to 3,5-tBu2C6H3CMe2CH2, before binding to Co. The organocobalt species generated in this way react further
可以通过Na / Hg还原LCoCl 2或氢解LCoCH 2 SiMe 3来制备形式上为Co(0)的配合物LCo(N 2)(L = 2,6-双(2,6-二甲基苯基亚氨基乙基)吡啶)。在后一反应中,LCOH可以通过与N≡CC反应被截留6 ħ 4 -4-CL,得到LCoN═CHC 6 ħ 4 -4-CL。LCo(N 2)与许多烷基和芳基卤化物RX(包括芳基氯化物)反应,在卤素原子提取机理中得到LCoR和LCoX的混合物。游离烷基和芳基的中间体通过环丙基甲基对巴豆基的开环和2,4,6- t Bu的重排得到证实3 C 6 H 2至3,5- t Bu 2 C 6 H 3 CMe 2 CH 2,然后与Co结合。以这种方式生成的有机钴物质进一步与活化的卤化物R'X(烷基碘;烯丙基和苄基卤化物)反应)以最有可能再次是卤素提取机理的方式产生交叉偶联产物RR'。DFT研究支持为这两个步骤建议的基本途径。MeI与LCoCH