Efficient synthesis of 3,3′,5,5′-tetra(p-X-phenylethynyl)biphenyl (X: NMe2; OMe) by homocoupling of 1-bromo-3,5-di(p-X-phenylethynyl)benzene or by heterocoupling of 3,3′,5,5′-tetraethynylbiphenyl with p-X-phenylbromobenzene with nickel or palladium complexes, respectively
作者:J. Gonzalo Rodríguez、Teresa Laparra
DOI:10.1016/j.tet.2009.01.036
日期:2009.3
The conjugated 3,3',5,5'-tetra(p-X-phenylethynyl)biphenyl derivatives were efficiently obtained by homocoupling of 1-bromo-3,5-di(p-X-phenylethynyl)benzene mediated by zero-valent nickel complexes. The 1-bromo 3,5-di(p-X-phenylethynyl)benzene was previously prepared by heterocoupling between 1-bromo-3,5-di(ethynyl)benzene and p-X- iodobenzene (X: NMe2; OMe) catalysed by the palladium/copper system in good yield. The necessary 1-bromo-3,5-di(ethynyl)benzene was obtained by heterocoupling between 1,3,5-tribromobenzene and 2-methyl-3-butyn-2-ol catalysed by palladium and successive treatment with sodium hydroxide in dry toluene, in good yield.The same 3,3',5,5'-tetra(p-X-phenylethynyl)biphenyl (X: NMe2; OMe) derivatives were alternatively synthesised in highest yield by heterocoupling between 3,3',5,5'-tetra(ethynyl)biphenyl and p-X-bromobenzene (X: NMe2; OMe) catalysed by palladium in excellent yields. Previously, 3,3',5,5'-tetra(ethynyl)biphenyl was obtained in practically quantitative yield by homocoupling of 1-bromo-3,5-di-[4-(2-methyl-3-butyn-2-ol)] benzene mediated by the zero-valent nickel complex to the 3,3',5,5'-tetra[di-[4-(2-methyl-3-butyn-2-ol)] followed the treatment with sodium hydroxide. (C) 2009 Published by Elsevier Ltd.