CROSS-COUPLING REACTIONS BETWEEN SP^2-CARBON AND SP CARBON USING PALLADIUM COMPLEXES AND COPPER IODIDE

Pd/ cu催化sp^2 C卤化物与末端乙炔之间的交叉偶联反应为合成共轭炔提供了一种有用的方法，在从抗癌药物到材料科学的各个领域都有应用。在标准的（Ph_3P）_2PdCl_2/CuI/胺催化体系下，末端乙炔与芳香溴化物的交叉偶联反应需要较高的温度，这可能导致乙炔的低聚反应，而不是相应的碘化物。得到了芳基溴与苯乙炔偶联的最佳催化条件：苯乙炔（1.5等当量），C_6H_5Br（1.0等当量），Bu_4NI(10摩尔%),CuI(4摩尔%),DMF/^nBuNH_2=20/1 70℃。含有富电子大体积磷化氢的（PhCN）_2PdCl_2/^tBu_3P，/CuI催化剂在室温下对芳基溴的交叉偶联是有效的[S]。l·布奇华。等人。列托人。2, 1729(2000)]。含有（R_3P）_2PdCl_2、R_3P = P^tBu_2、P^tBu_2（o-C_6H_4OMe）、P^tBu_2Ph、P^tBu_2（C_4H_3S）和1,1双（二叔丁基）磷酸二茂等富电子大体积磷化氢的pd -络合催化剂也可作为上述体系的替代品。通过对L_2PdCl_2、双核Pd配合物（R_3P）_2Pd_2Cl_4和螯合Pd配合物L- lpdcl_2的催化活性的比较，得出单核Pd配合物的L_2Pd【互变异构体】LPd + L和螯合膦配合物的水溶液溶剂分别在催化循环中起作用。

The Pd/Cu-catalyzed cross-coupling reaction between sp^2 C halides and terminal acetylenes provides a useful method for synthesizing conjugated alkynes that have found application in diverse area ranging from anticancer drugs to material science. The cross coupling reaction of terminal acetylenes with aromatic bromides using standard catalytic systems, (Ph_3P)_2PdCl_2/CuI/amine, requires higher temperature, which may cause some oligomerization of acetylenes, than those of the corresponding iodides. The following optimum catalytic conditions for the coupling of aryl bromides with phenyl acetylene are obtained ; phenyl acetylene (1.5 equiv.), C_6H_5Br(1.0 equiv.), Bu_4NI(10 mol%), CuI(4 mol%), DMF/^nBuNH_2=20/1 70℃. The catalyst, (PhCN)_2PdCl_2/^tBu_3P,/CuI containing electron rich bulky phosphine, have recently been shown to be effective for the cross-coupling of aryl bromides at room temperature [S. L. Buchwald. et al, Org. Lett.,2, 1729(2000)]. The Pd-complex catalyst containing electron rich bulky phosphine such as (R_3P)_2PdCl_2,R_3P = P^tBu_2, P^tBu_2(o-C_6H_4OMe), P^tBu_2Ph, P^tBu_2(C_4H_3S) and 1,1 bis(ditertiarybutyl)phosphinoferrocene, can be also used as an alternative to the above system. From the comparison of the catalytic activities of three types of mononuclear Pd complexes, L_2PdCl_2, dinuclear Pd complexes, (R_3P)_2Pd_2Cl_4, and Chelate Pd complexes, L-LPdCl_2, we conclude that the equilibrium, L_2Pd 【tautomer】 LPd + L, for the mononuclear Pd complexes, and an aqueous solvents for the chelate phosphine complex play a role in the catalytic cycle, respectively.