Intermolecular Hydrogen Transfer And C-h Activation By Means Of Palladium-catalyzed Domino Reaction

In this paper, we mainly study that the aromatic C-H activation Domino reaction of eneyne in the palladium-catalyzed, and we find that hydrogen transferring in this reaction.1. Pdlladium-Catalyzed Cyclization Reaction of Aryl Halides with Eneyne involving Nitrogen.Eneyne substrate ( a,b,c,d,e,f ) reacts with the aryl halides ( R-C6H4X, R = H, p-SOOCH3, p-Cl, o-Cl, p-COCH3, p-CN, p-CHO, p-COOCH2CH3, p-COOCH3; X=Br) by the palladium acetate under the argon, as a result, it forms some cyclization products and autocyclization products. By controlling the reaction conditions can get the different yields of the products. The experiment results showed that the different products were got in high yields through controlling the reaction temperature at 135oC. The most seemly base is (n-Bu)₃N and the perfect solvent is DMF. In this series of experiments, we can get two cyclization products because of hydrogen transferring. One is the autocyclization products ( a', b, ) , and the second is the singlecyclization products ( aa, ab, ac, ad, ae, ba, bb, bc ). However, we can only get autocyclization products ( c', d', e', f' ) due to the electronic effect. The complex prouducts were obtained through two various palladium catalytic circle processes, also the C-C coupling cyclization and the C-H activation.2. Pdlladium-Catalyzed Cyclization Reaction of Aryl Halides with 1,6-dienes involving Nitrogen.Based on the above experimental results,we looked forward to using our previous substrates to produce a similar product under the same reaction conditions, but not achieved the expected products, and only obtain the autocyclization products ( g', h', i, ), even though changed the temperature, base or solvent etc.In this paper, we have developed an efficient synthesis of autocyclization via an domino cyclization of eneyne with aryl halides, which provides good yields. In addition, the method of multi-steps cyclization introduced can be extented to construct many other core structures of natural products.