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张超峰

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A variety of electron-rich heterocycles can be arylated
using this methodology (Table 2). Thiophene and ben-zothiophene are reactive (entries 1-3). Both 1,2- and 1,3-oxazole derivatives can be arylated (entries 4 and 6-8).Benzofuran is diarylated in a reasonable yield (entry 5).
Thiazole and benzothiazole arylation is also successful
(entries 9 -12). In 2-substituted thiazoles, the aryl group is
introduced next to sulfur (entries 11 and 12). 1- n- Butylimi-dazole is arylated in the 5-position, with some diarylationproduct also formed (entry 13). 1-Methyl-1,2,4-triazole is selectively arylated in the 5-position (entry 14). Caffeine is
very reactive, and some of the products are of interest as adenosine receptor antagonists (entries 15 -17).
If C -H activation methodology is not used, the synthetic sequences
leading to these compounds require several steps instead of
a single step.Amide substitution is tolerated on both aryl
chloride and the heterocycle (entries 1 and 12), and the N -H
bond is not arylated.Chlorobenzoic acid esters can also be
used (entry 7). 2-Chloropyridines are reactive (entries 2 and
6), and the products of these arylations may find use as
chelating ligands. Both electron-rich and electron-poor aryl
chlorides can be used; however, as expected, electron-poor
chlorides are more reactive. Some steric hindrance is tolerated
on the heterocycle (entry 4) and aryl chloride (entry 16).
Arylation ofN-methylindole under the standard conditions
resulted in low conversion (ca. 20%).
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爱与雨下: 金币+2 2012-04-30 09:00:36
爱与雨下: , 节日快乐 2012-04-30 09:00:49
张超峰: 金币+50, 翻译EPI+1 2012-05-01 17:33:40
各种多电子杂环化合物可以用这种方法芳香化(见表2)。噻吩和苯并噻吩都具有反应活性( 1-3项) 。 1,2 - 和1,3 - 恶唑衍生物也可被芳香化( 4和6-8项),苯并呋喃在一个合理的产量下二次芳香化( 5项),唑和噻唑芳基化也是成功的( 9至12项) 。在2 - 取代噻唑,芳香基的介绍了紧挨着硫( 11和12项) 。1-异丁基咪唑在5号位置上选择性的芳香化,且有一些二次芳香化产物( 13项) 。 1 - 甲基-1,2,4 - 三唑选择性在5号位芳香化( 14项) 。咖啡因的反应活性很强,且部分产品非常有趣可作为腺苷受体拮抗剂(条目15-17 )。如果不使用C-H键的活化方法,这些化合物的合成需要几个步骤,而不是单一的步骤.氨基取代反应可发生在氯苯及杂环化合物上( 1和12项), 且N-H键不被芳香化。氯化安息香酸酯也可以用( 7项) 。 2 - 氯吡啶也具有反应活性( 2和6项) ,这些芳香化的产品可用作螯合配体。多电子和缺电子的氯代芳烃也可以用,但是,正如所料,缺电子氯化物的反应活性更高。杂环( 4项)和芳基氯化物( 16项)上有不可忽视的空间位阻是。标准条件下N - 甲基吲哚的芳香化的转化率较低(约20% ) 。
如若这般,当初又为了什么?
2楼2012-04-29 18:30:10
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