How flexible are poly(para-phenyleneethynylene)s?
How flexible are poly(para-phenyleneethynylene)s?
复制标题
DOI：
10.1002/anie.200602807
复制
发表时间：
2006-01-01
影响因子：
16.6
通讯作者：
Jeschke, Gunnar
中科院分区：
文献类型：
--
作者：
Godt, Adelheid;Schulte, Miriam;Jeschke, Gunnar
对于化合物4和5的合成（方案1），使用为合成较短的类似物2和3而开发的程序。[1]从容易获得的低聚亚苯基亚乙炔基结构单元6a、B [2]开始，其具有用于末端炔基的两个正交保护基团，获得芳基炔7a、B。由于它们易于分解，[2]炔7a、B在分离后立即分别与芳基碘8或9偶联。通过与Bu 4 NF的反应除去偶合产物10 a、B的炔保护TIPS基团，并在Pd（PPh 3）2Cl 2和CuI的存在下，用空气作为氧化剂，使由此获得的炔11 a、B氧化二聚（Glaser偶合）。在酸的存在下用甲醇处理被保护的二酚12 a、B以使OH基团脱保护，所述OH基团用于最终连接自旋标记1-氧基-2，2，5，结构单元8通过炔14与1.5当量的二碘化合物15的偶联得到（方案2）。反应混合物由二碘化合物15、单偶联产物8和双偶联产物16 [1]以4.7：5.0：1.0的比例组成，如通过1H NMR光谱测定的。通过柱色谱法分离这三种产物。
For the synthesis of compounds 4 and 5 (Scheme 1) the procedures developed for the synthesis of the shorter analogues 2 and 3 were used.[1] Starting from the readily available oligophenyleneethynylene building blocks 6a, b [2] with two orthogonal protecting groups for the terminal alkyne groups, the aryl alkynes 7a, b were obtained. Because of their tendency to decompose,[2] alkynes 7a, b were coupled with the aryl iodides 8 or 9, respectively, immediately after having been isolated. The alkyne protecting TIPS group of the coupling products 10a, b was removed through the reaction with Bu4NF and the thus obtained alkynes 11a, b were oxidatively dimerized (Glaser coupling) in the presence of Pd (PPh3) 2Cl2 und CuI with air as the oxidant. The protected diphenols 12a, b were treated with methanol in the presence of an acid to deprotect the OH groups which were used to attach finally the spin label 1-oxyl-2, 2, 5, 5-tetramethylpyrroline-3-carboxylic via an ester bond formation yielding the diradicals 4 and 5.The building block 8 was obtained through a coupling of alkyne 14 with 1.5 equivalents of diiodo compound 15 (Scheme 2). The reaction mixture consisted of diiodo compound 15, monocoupling product 8 and dicoupling product 16 [1] in a ratio of 4.7: 5.0: 1.0 as determined by 1H NMR spectroscopy. These three products were separated by column chromatography.