Synthesis of Biaryls and Oligoarenes Using Aryl[2-(hydroxymethyl)phenyl]dimethylsilanes
作者:Jinshui Chen、Masaaki Tanaka、Akhila K. Sahoo、Masahide Takeda、Akira Yada、Yoshiaki Nakao、Tamejiro Hiyama
DOI:10.1246/bcsj.20090325
日期:2010.5.15
Through intramolecular activation, highly stable aryl[2-(hydroxymethyl)phenyl]dimethylsilanes can selectively transfer their aryl groups to effect a cross-coupling reaction with various aryl bromides and chlorides in the presence of a weak non-fluoride base and a palladium/copper catalyst. This reaction tolerates a wide range of functional groups, producing the corresponding functionalized biaryls in high yields with excellent chemoselectivity. Newly disclosed reaction conditions allow the recovery of a cyclic silyl ether in modest-to-good yields and reuse for the synthesis of the arylsilanes. The introduction of two isopropyl groups on the silicon center instead of methyl groups improves the stability and allows quantitative recovery of the silicon residue. Finally, aryl halides having an O-protected [2-(hydroxymethyl)phenyl]dimethylsilyl group cross-couple with the arylsilane reagents to give silyl-functionalized biaryls. Upon deprotection, the biaryls further react with the silylated electrophiles. The iterative cross-coupling–deprotection sequences allow rapid assembly of silylated oligoarenes. Syntheses of di- and trisilyloligoarenes are also achieved by use of orthogonal O-protecting groups.
通过分子内活化,高度稳定的二甲基[2-(羟甲基)苯基]硅烷可以将其苯基选择性地转移到各种含有苯基卤化物的芳基溴化物和氯化物上,在非氟化弱碱和钯/铜催化剂的存在下进行交联反应。该反应耐受广泛的功能基团,以高产率和高化学选择性生成相应的功能化双芳基化合物。新披露的反应条件允许以中等至良好的产率回收环状硅醚,并可重复使用于合成芳基硅烷。在硅中心引入两个异丙基取代甲基可提高稳定性,并能定量回收硅残基。最后,拥有保护性O-[2-(羟甲基)苯基]二甲基硅烷基团的芳基卤化物与芳基硅烷反应剂交联,生成含硅功能化双芳基化合物。去保护后,双芳基化合物再与硅化亲电试剂反应。通过交叉耦合-去保护序列的迭代,可以快速组装含硅的寡芳烃。通过使用正交氧保护基团,还可以实现二硅和三硅寡芳烃的合成。