Efficient Preparation of Photoswitchable Dithienylethene-Linker-Conjugates by Palladium-Catalyzed Coupling Reactions of Terminal Alkynes with Thienyl Chlorides and Other Aryl Halides
作者:Marc Zastrow、Sujatha Thyagarajan、Saleh A. Ahmed、Paul Haase、Sabine Seedorff、Dmitri Gelman、Josef Wachtveitl、Elena Galoppini、Karola Rück-Braun
DOI:10.1002/asia.200900503
日期:2010.5.3
iodo‐substituted linker 8. Reaction conditions for the final Sonogashira coupling step between ethynylene‐linker 5 with the chloro‐substituted dithienylethene 4 in the presence of [PdCl2(CH3CN)2]/X‐Phos and Cs2CO3 or K3PO4 are optimized using 2‐chloro‐5‐methylthiophene (9) and triethylsilylacetylene or triisopropylsilylacetylene (10a, 10b,) as model compounds. Experimental conditions are found to suppress the
合成了三种具有金刚烷核的光致变色二噻吩乙烯-接头共轭物,其中金刚烷核的间隔长度和覆盖面积均带有羧基锚定基团。合成途径从乙炔基连接基5或碘取代基连接基8开始。为最后的Sonogashira偶联亚乙炔基-接头之间步骤的反应条件5与氯取代的dithienylethene 4在存在[的PdCl 2(CH 3 CN)2 ] / X-PHOS和Cs 2 CO 3或K 3 PO 4进行了优化使用2-氯-5-甲基噻吩(9)和三乙基甲硅烷基乙炔或三异丙基甲硅烷基乙炔(10a,10b,)作为模型化合物。发现实验条件抑制了TIPS-乙炔10b中C(sp)Si键的活化,该反应导致随后的交叉偶联反应形成副产物12。此外,在氯取代的二噻吩基乙烯4的氟化主链存在下,也可以防止C(sp)Si键的活化。还研究了缀合物3及其前体二噻吩基乙烯7b的光致变色性质。