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C-N键普遍存在于药物和有机功能分子中,传统构建C-N键的方法包括Goldberg反应、Buchwald-Hartwig偶联、Chan-Lam偶联和C-H键活化胺化.虽然这些方法都可以高效构建C-N键,但它们需要使用官能化的芳基底物、官能化的胺化试剂或在氧化条件下进行.理想的胺化反应应在氧化还原中性条件下进行,更为理想的则是在引入氨基的同时引入另外一个官能团.实现这个目标最直接的策略就是使用氮杂环,通过N-E(E=N或O)键的断裂,N原子和E原子可同时被引入.最近我们课题组利用氨茴内酐和氮杂苯并降冰片烯的C-H键活化反应成功实现了这种双官能团化.尽管该法很有吸引力,但是要通过氮杂环的断裂实现双官能团化,需要发生非张力环的开环,这在热力学上是非常不利的.苯并呋咱-1-氧化物可以开环得到邻二硝基苯中间体.基于对胺化反应的兴趣,我们推测苯并呋咱1-氧化物可以作为一个胺化试剂实现苯硼酸的胺化.尽管亚硝基苯对芳基硼酸进行简单的胺化已经被报道,但需要化学计量的铜盐,或是引入还原剂.因此本文报道铜催化的苯硼酸的胺化反应,该反应以苯并呋咱1-氧化物为胺化试剂,在温和及氧化还原中性条件下成功实现了双官能团化.本文共完成了31个不同官能团取代的硝基苯胺骨架结构的合成,反应均以中等到良好的收率得到目标产物,最高收率可达99%.为了增加反应的实用性,我们还进行了放大实验,实验表明,当苯并呋咱-1-氧化物的量由0.2 mmol放大至4 mmol时,反应仍能以较高的收率得到目标产物.此外,目标产物通过进一步的衍生化反应还可方便地转化为其他杂环类化合物.例如,在PPh_3作用下,通过还原环化作用可生成吩嗪.在钯催化下可发生分子内碳氢键氧化反应得到咔唑类化合物.通过还原及重氮化反应还可方便地转化为苯并三唑.总之,我们以苯并呋咱-1-氧化物为胺化试剂,在铜催化下成功实现了苯硼酸的胺化反应,合成了一系列双官能团化产物.该催化体系反应条件温和,底物适用范围广,对各种官能团具有很好的兼容性.
CN bonds are commonly found in pharmaceutical and organic functional molecules. The traditional methods for constructing CN bonds include Goldberg reaction, Buchwald-Hartwig coupling, Chan-Lam coupling and CH bond activation amination. Although these methods can efficiently construct CN bonds, But they require the use of functionalized aryl substrates, functionalized amination reagents or under oxidizing conditions.The ideal amination reaction should be carried out under redox neutral conditions, more desirably at the same time as the introduction of amino groups The introduction of another functional group to achieve this goal the most direct strategy is the use of nitrogen heterocycles, through the NE (E = N or O) bond fracture, N atoms and E atoms can be introduced at the same time recently our group using ammonia anisidine And azabenzor norbornene CH activation reaction successfully achieved this bifunctionalization.Although the method is very attractive, but through the nitrogen heterocycle cleavage to achieve bifunctionalization, the need to occur non-tension ring open Ring, which is thermodynamically very unfavorable. Benzofurazan-1-oxide can be ring-opened to give an o-dinitrobenzene intermediate. Based on the interest in the amination reaction, we hypothesized that benzofurazan 1-oxide Can serve as an amine Reagents Amination of Benzeneboronic Acid.Although nitrobenzene has been reported for simple amination of arylboronic acids but requires stoichiometric copper salts or the introduction of reducing agents.Therefore, it is reported herein that copper-catalyzed Amination, the reaction with benzofurazan 1-oxide as an amination reagent, in a mild and redox neutral conditions successfully achieved bifunctionalization.In this paper, a total of 31 different functional groups substituted nitroaniline skeleton The synthesis and reaction of the structure all achieved the target product with moderate to good yield with the highest yield up to 99%. In order to increase the practicability of the reaction, we also carried out an amplification experiment. The results showed that when benzofurazan- When the amount of oxide is enlarged from 0.2 mmol to 4 mmol, the target product can still be obtained in a higher yield.In addition, the target product can be conveniently converted into other heterocyclic compounds by further derivatization reaction.For example, Under the action of PPh_3, phenazine can be formed by reductive cyclization, and carbazole compounds can be obtained by intramolecular carbon-hydrogen bond oxidation catalyzed by palladium. It can also be easily converted into benzotriazole by reduction and diazotization reaction In short, I The benzofurazan-1-oxide as an amination reagent, under the catalysis of copper successfully aminobenzeneboronic acid reaction, a series of bifunctional products were synthesized.The reaction system is mild, the scope of the substrate Wide, a variety of functional groups have good compatibility.