A Three-Step Synthetic Approach to Asymmetrically Functionalized 4<i>H</i>-Cyclopenta[2,1-<i>b</i>:3,4-<i>b′</i>]dithiophenes
作者:Sarah Van Mierloo、Peter J. Adriaensens、Wouter Maes、Laurence Lutsen、Thomas J. Cleij、Edith Botek、Benoît Champagne、Dirk J. Vanderzande
DOI:10.1021/jo101405j
日期:2010.11.5
final Friedel−Crafts dehydration cyclization in sulfuric acid medium, these derivatives were converted to 4,4-dialkyl-4H-cyclopenta[2,1-b:3,4-b′]dithiophenes. Upon replacement of the dialkyl ketone reagent by ethyl levulinate, an ester-functionalized 4H-cyclopenta[2,1-b:3,4-b′]dithiophene was prepared, representing an attractive precursor for variously functionalized cyclopentadithiophene compounds
已经开发了一种方便有效的向对称和不对称官能化的4 H-环戊[2,1- b:3,4- b ']二噻吩进行三步反应的途径。使用此方法,可以顺利访问功能化的桥接联噻吩的广泛集合。由3-噻吩-2-2,2'-联噻吩开始,在Pd(dppf)Cl 2催化下,2-噻吩基溴化镁与2,3-二溴噻吩的Kumada偶联制备,锂化并随后与二烷基酮反应,得到(a)对称的二烷基化叔醇衍生物。通过在硫酸介质中的最终Friedel-Crafts脱水环化反应,将这些衍生物转化为4,4-二烷基-4 H-环戊[2,1- b:3,4- b ']二噻吩。用乙酰丙酸乙酯代替二烷基酮试剂后,制备了酯官能化的4 H-环戊基[2,1- b:3,4- b ']二噻吩,它代表了各种官能化的环戊二噻吩化合物的有吸引力的前体。