钌催化N-乙酰基α-芳基乙烯胺与芳基乙烯的高化学选择性和区域选择性二聚

Ruthenium Catalyzed Highly Chemo-and Regio-selective Codimerization of N-Acetyl α-Arylethenamines with Vinylarenes

过渡金属催化的烯烃的二聚反应是碳-碳键形成的重要反应之一.因其原料易得、原子经济、且具有很好的工业应用前景而已得到深入、广泛的研究.系统研究了钌催化N-乙酰基烯胺与烯烃的二聚反应,发现在钌氢络合物RuHCl(CO)(PCy3)2的催化下可实现系列N-乙酰基α-芳基乙烯胺1与芳基乙烯4的高化学选择性和区域选择性二聚,并以高达99%的收率得到头对尾的多取代烯酰胺5.依据反应结果及反应中观测到的现象,提出了芳基乙烯4先与活化的钌氢中间体发生插入反应形成类烯丙基中间体,然后与N-乙酰基α-芳基乙烯胺1发生二聚反应生成多取代烯酰胺5的可能机理,并对反应中观测到的现象进行了合理的解释.

Transition metal catalyzed codimeriaztion of alkenes is an important carbon-carbon bond forming reaction.This efficient reaction has the properties of easily available of starting materials,atomic economy,and good prospects for industrial application,and has been received in-depth and intensive study during the past decades.In this paper,we have systematically studied the ruthenium catalyzed codimerization of N-acetyl enamides with alkenes and found that the ruthenium hydride complex RuHCl(CO)(PCy3)2 is highly efficient catalyst for the codimerization of N-acetyl α-arylethenamines 1 with vinylarenes 4,providing the head-to-tail hetero-codimerized products,poly-substituted N-acetyl enamides 5 with high chemo-and regio-selectivity and up to 99% yield.According to the results and the observed phenomena of the codimerization reaction,we proposed a reaction mechanism that the vinylarenes 4 was firstly inserted into the Ru-H bond of the activated ruthenium hydride intermediate to form an allylic metal-intermediate and then codimerized with N-acetyl α-arylethenamines 1 to generate the hetero-codimerized poly-substituted N-acetyl enamides 5.With this proposed reaction mechanism the reaction results and the observed phenomena can be rational explanation.