二卤海因参与的(取代苯基)-(吡啶-2-基)-甲酮类化合物的卤化反应

Halogenations of (substituted phenyl)(pyridin-2-yl) methanones with 1,3-dihalo-5,5-dimethylhydantoin

摘要:

以(取代苯基)-(吡啶-2-基)-甲酮类化合物为原料，二溴海因和二氯海因为溴源和氯源，1,2-二氯乙烷为溶剂，通过醋酸钯催化的卤化反应，实现了该类化合物的邻位溴代和氯代，得到18种(卤代苯基)-(吡啶-2-基)-甲酮类化合物，并采用1HNMR、13CNMR对产物进行了结构鉴定。从底物普适性研究可知，对不同取代基的苯基-(吡啶-2-基)-甲酮类化合物进行邻位溴代或氯代，得到中等或良好的产率。研究发现，二溴海因的反应活性比二氯海因高。控制实验表明该反应为碳氢活化卤代反应，并提出了一种可能的反应机理。

Abstract:

With dibromohydantoin and dichlorohydantoin as halogen sources, 18 (halogenated phenyl)(pyridin-2-yl) methanones were prepared by Pd(OAc)2 catalyzed C—H halogenation from (substituted phenyl)(pyridine-2-yl) methanones in 1,2-dichloroethane. Their structures were determined by 1HNMR and 13CNMR. A range of (halogenated phenyl)(pyridin-2-yl) methanones with wide functional group tolerance was obtained in moderate to good yields. Furthermore, the results indicate that the halogenation ability of dibromohydantoin is higher than dichlorohydantoin. In addition, a possible reaction pathway was proposed as a C–H bond activation-halogenation process based on the results of control experiments.