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维尔斯迈尔反应,芳香杂环上醛基

优良自学吧提供维尔斯迈尔反应,芳香杂环上醛基,如图,我做了这个反应,之前一个类似的反应,我在寻求帮助的时候引发了众人的机理大战,这次不想了。只是想虚心请教一下。这个反

如图,我做了这个反应,之前一个类似的反应,我在寻求帮助的时候引发了众人的机理大战,这次不想了。只是想虚心请教一下。这个反应我用的还是维尔斯迈尔反应,即用DMF和POCl3. 原料1.0  DMF1.2   POCl3 1.2   就是想请教下,这个醛基会加在哪 ,A还是B呢?  如果我想得到更多的A 是不是 投料比例要精确控制?

QQ截图20150731110920.png
------解决方案--------------------
噻吩富电子,a位电子云密度最高,所以主产物应该是2位的。控制温度和当量,放心做吧
------解决方案--------------------
应该是A,做做试试。
------解决方案--------------------
我做过类似的,LDA拔氢上醛基,就是实验操作麻烦点,但是产物干净,后处理方便,产率高。醛上2位
------解决方案--------------------
5-Methoxythiophene-2-carbaldehyde, used as starting material, was prepared as follows:-A solution of n-butyllithium (35.5mL, 56.93mmol, 1.3eq 1.6M in hexanes) was added to a solution of 2-methoxythiophene (5g, 43.79mmol, 1eq) in ethoxyethane (100mL) at 0°C under nitrogen. The reaction was stirred for 15 mins and then DMF (4.41ml, 56.93mmol, 1.3eq) was added dropwise. The temperature was allowed to rise to 25°C over 15 mins. The mixture was heated at 35°C for 1 h and then allowed to cool to room temperature and poured into water. The mixture was extracted with diethyl ether (×3), the organics were washed with brine, dried (MgSO4) and evaporated to give crude product as a yellow liquid (7.2g, >100%). 1H NMR (400.13MHz CDCl3) δ 3.99 (1H, s), 6.34 (1H, d), 7.51 (1H, d), 9.67 (1H, s)

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