Grignard reactions on ortho dicarboxylic arene derivatives. Synthesis of 1,3-dithienylisothianaphthene compounds
Grignard reactions on ortho dicarboxylic arene derivatives. Synthesis of 1,3-dithienylisothianaphthene compounds
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DOI：
10.1021/jo9604402
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发表时间：
1997-03-07
影响因子：
3.6
通讯作者：
Gelan, JMJV
中科院分区：
文献类型：
--
作者：
Kiebooms, RHL;Adriaensens, PJA;Gelan, JMJV
1,3-二噻吩基异硫茚(10a)是通过1,2-二噻吩酰基苯(7a)的闭环得到的。 7a的合成基于格氏反应，通过将2-噻吩-溴化镁加入到1，2-二(S-(2-吡啶基))苯二硫代酸酯(6b)中，得到7a，收率95％。 6b的使用避免了相应的3,3-二噻吩基-3H-异苯并呋喃-1(3H)-酮（二噻吩基苯酞，8）的形成。应用相同的程序以获得1,3-二噻吩基-4,5,6,7-四氘异硫茚(10b)和1,3-二噻吩基-4,5,6,7-四氟异硫茚(10c)。然而，2,3-二噻吩甲酰吡啶(12a)、3,4-二噻吩甲酰吡啶(12b)和2,3-二噻吩甲酰吡嗪(12c)的合成失败。中心环系统中氮的存在影响格氏反应的结果。氮的自由电子对可能会干扰稳定的六元环中间体的形成，这对于二酮的形成至关重要。
1,3-Dithienylisothianaphthene (10a) is obtained through ring closure of 1,2-dithienoylbenzene (7a). The synthesis of 7a has been accomplished based on a Grignard reaction by adding 2-thiophene-magnesium bromide to 1,2-di(S-(2-pyridinyl)) benzenedithioate (6b) to obtain 7a in a yield of 95%. The use of 6b avoids the formation of the corresponding 3,3-dithienyl-3H-isobenzofuran-1(3H)-one (dithienylphthalide, 8). The same procedure is applied to obtain 1,3-dithienyl-4,5,6,7-tetradeuterioisothianaphthene (10b) and 1,3-dithienyl-4,5,6,7-tetrafluoroisothianaphthene (10c). The synthesis of the 2,3-dithienoylpyridine (12a), 3,4-dithienoylpyridine (12b), and 2,3-dithienoylpyrazine (12c) however fails. The presence of nitrogen in the central ring system influences the result of the Grignard reaction. Possibly the free electron pair of the nitrogen interferes with the formation of a stable six-membered ring intermediate which is essential for the diketone formation.