作者:Tatsuya Kawanishi、Kosuke Ishida、Eiichi Kayahara、Shigeru Yamago
DOI:10.1021/acs.joc.9b02844
日期:2020.2.21
Selective and large-scale synthesis of [8]cycloparaphenylene (CPP) was achieved in seven steps starting from commercially available 4-bromo-4'-hydroxybiphenyl and 4,4'-dibromobiphenyl. The key unsymmetrical tetraring unit, 4-bromophenyl and 4'-bromobiphenyl-substituted cis-1,4-bis(triethylsiloxy)-2,5-cyclohexadiene-1,4-diyl (5fA), was synthesized on an ∼50 g scale by stereoselective cis-addition of
从商业上可获得的4-溴-4'-羟基联苯和4,4'-二溴联苯开始,分七个步骤实现了[8]环对亚苯基(CPP)的选择性和大规模合成。以〜50 g的规模合成了关键的不对称四环单元4-溴苯基和4'-溴联苯取代的顺1,4-双(三乙基甲硅烷氧基)-2,5-环己二烯-1,4-二基(5fA)通过将4-溴-4'-硫代联苯立体选择性顺式加成到4-(4-溴苯基)-4-羟基-2,5-环己二烯-1-酮上,该合成量约为100 g。铂介导的四环单元5fB的选择性二聚和随后的H2SnCl4还原环己二烯二基的芳构化反应,可得到2 g [8] CPP,总产率为6.6%(小规模为10.2%)。