Facile Synthesis of 3‐(ω‐Haloalkyl)thiophenes as Key Building Blocks for Functionalized Thiophenes and Polythiophenes
Facile Synthesis of 3‐(ω‐Haloalkyl)thiophenes as Key Building Blocks for Functionalized Thiophenes and Polythiophenes
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轻松合成 3-(ω-卤代烷基)噻吩作为功能化噻吩和聚噻吩的关键构建单元
DOI：
10.1002/anie.199004191
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发表时间：
1990
期刊：
影响因子：
--
通讯作者：
S. Heid
中科院分区：
文献类型：
--
作者：
P. Bäuerle;F. Würthner;S. Heid
在烷基链上含有末端离去基的3-烷基噻吩是合成功能化3-烷基噻吩和聚（3-烷基噻吩）的中心中间体，目前这两种化合物在2位和s位上偶联形成共轭聚合物，从而允许官能团通过3位（或4位）的烷基链进行共价附着。功能化的3-烷基噻吩以前只能从3-甲基噻吩[~]或3-（2-氢~乙基）噻吩[~]开始，通过一系列繁琐的链加长步骤才能得到。此外，烷基链较短的化合物难以聚合。[4a1]我们现在已经开发出一种简便的3-烷基噻吩的合成方法，在长度为n24的烷基链上含有末端卤素取代基。这些化合物可作为制备功能化3-烷基噻吩和聚3-烷基噻吩的关键组成部分。[~~]由于3-锂噻吩在烷基化反应中的使用受到限制，[61]通过镍催化的烷基溴化镁与3-溴噻吩的格氏偶联[71]来合成3-烷基噻吩，这是一种容易获得的新方法。[81]然而，将这一反应直接扩展到a，@-二卤代烷，并不能生成必要的单格氏化合物。[1]另一方面，a-（对甲氧基苯氧基）烷基溴1很容易由a、o二卤烷和对苯二酚单甲醚（HCM）制备，[1]很容易与镁反应生成相应的格氏化合物2[式(a)]。化合物1 ae （n= 4- 6,8, 10）经过近定量
3-Alkylthiophenes containing a terminal leaving group in the alkyl chain are central intermediates for the synthesis of functionalized 3-alkylthiophenes and poly (3-alkylthienylenes), which are currently under intensive The coupling of monomeric thiophenes to form conjugated polymers occurs at the 2-and S-positions,['I thereby allowing covalent attachment of functional groups via alkyl chains in the 3-position (or 4-position). Functionalized 3-alkylthiophenes were previously only accessible starting from 3-methylthi~ phene [~] or 3-(2-hydro~ yethyl) thiophene [~] by a tedious sequence of chain-lengthening steps. Moreover, those with shorter alkyl chains are difficult to polymerize.[4a1 We have now developed a facile synthesis of 3-alkylthiophenes containing a terminal halogen substituent on an alkyl chain of length n 2 4. These compounds may be used as key building blocks for the preparation of functionalized 3-alkylthiophenes and poly (3-aIkylthienylene~).[~~Since the use of 3-lithiothiophene in alkylation reactions is restricted,[61 the synthesis of 3-alkylthiophenes was approached via nickel-catalyzed Grignard couplings [71 of alkylmagnesium bromides with 3-bromothiophene, which is readily accessible by a new procedure.[81 The direct extension of this reaction to a,@-dihaloalkanes, however, does not lead to the necessary mono-Grignard compounds.[g1 On the other hand, the a-(p-methoxyphenoxy) alkyl bromides 1, easily prepared from a, o-dihaloalkanes and hydroquinone monomethyl ether (HCM),[lo1 react readily with magnesium to give the corresponding Grignard compounds 2 [Eq.(a)]. Compounds 1 ae (n= 4-6, 8, 10) undergo nearly quantita-