吡啶侧链C-H键氧化生成酮的研究

发布时间：2018-03-14 19:51

  本文选题：吡啶　切入点：C-H键　出处：《大连理工大学》2017年博士论文　论文类型：学位论文

【摘要】：含有吡啶结构的酮是合成医药、天然产物、农用化学品、染料等精细化学品的重要中间体,吡啶侧链C-H键的氧化是制备此类酮最直接、最高效的合成方法之一。由于吡啶环的缺电子性,其侧链C-H键比较难发生氧化反应,所以吡啶侧链C-H键氧化生成酮的研究很少。本论文选择苄基吡啶类化合物、6,7-二氢-5H-环戊基[b]吡啶类化合物和2-乙基吡啶作为反应底物,研究了吡啶侧链C-H键氧化生成酮的方法。主要内容如下:选择苄基吡啶类化合物作为反应底物,以氧气为氧化剂,研究了 H_4Nl-AcOH协同催化吡啶侧链C-H键氧化生成酮的方法,收率为61-97%。该方法具有优异的化学选择性,不氧化底物中的苄位甲基、苄位乙基和甲硫基。AcOH和苄基吡啶类化合物反应生成的盐促进了该氧化反应。对照实验证明了 H_4NI和AcOH协同催化的机理,H_4NI被氧化成I_2,I_2催化该氧化反应,AcOH不仅参与了H_4NI被氧化成I_2的过程,还提高了反应选择性。~(18)O_2同位素标记实验证明了酮产物中的羰基氧来自于氧气。电子顺磁共振(EPR)实验表明该氧化反应是通过自由基机理进行的。选择苄基吡啶类化合物、6,7-二氢-5H-环戊基[b]吡啶类化合物和2-乙基吡啶作为反应底物,研究了 Mn(OTf)2催化吡啶侧链C-H键氧化生成酮的方法,收率为31-88%。相比文献报道的方法,该方法使用了绿色环保的氧化剂(65%叔丁基过氧化氢水溶液)替代了 CrO3。文献报道的方法使用H_2SO_4-HOAc为溶剂,不仅对环境污染大,而且对设备腐蚀严重,本方法使用H_2O为溶剂,彻底解决了上述问题。通过单晶X射线衍射实验证明了 6,7-二氢-5H-环戊基[b]吡啶基-5-酮的结构。将Mn(NO_3)_2和1,10-菲Up啉的络合物在氮气氛围中煅烧制备了多种MnO_x-N@C,选择苄基吡啶类化合物和6,7-二氢-5H-环戊基[b]吡啶类化合物作为反应底物,研究了MnO_x-N@C催化吡啶侧链C-H键氧化生成酮的方法,收率为38-95%。研究发现MnO_x-N@C(600℃)的催化活性最高。利用透射电子显微镜(TEM)和X射线光电子能谱分析(XPS)对MnO_x-N@C(600 ℃)进行了初步表征。在连续循环6次后,MnO_x-N@C(600 ℃)的催化活性没有损失,这说明MnO_x-N@C(600 ℃)具有很好的稳定性。
[Abstract]:Ketones containing pyridine structure are important intermediates of synthetic medicine, natural products, agricultural chemicals, dyes and other fine chemicals. The oxidation of C-H bond of pyridine side chain is the most direct way to prepare such ketones. One of the most efficient synthesis methods. Due to the electron deficiency of pyridine ring, the side chain C-H bond is more difficult to oxidize. In this paper, benzylpyridine compounds (6) -dihydro-5H-cyclopentyl [b] pyridines and 2-ethylpyridine (2-ethylpyridine) were selected as the reaction substrates. The method of oxidation of pyridine side chain C-H bond to ketone was studied. The main contents were as follows: benzyl pyridine compounds were selected as reaction substrate and oxygen was used as oxidant to study the method of co-catalytic oxidation of pyridine side chain C-H bond to ketone by H _ 4Nl-AcOH. The yield is 61-97.The method has excellent chemical selectivity and does not oxidize benzyl methyl in the substrate. The oxidation reaction was promoted by the reaction of benzyl ethyl with trimethylthio. AcOH and benzyl pyridine compounds. The mechanism of co-catalysis of H _ (4NI) and AcOH was proved by comparison. The oxidation of H _ 4NI was oxidized to I _ 2N _ (2) and I _ 2i _ (2) was not only involved in the oxidation of AcOH. The process by which H4NI is oxidized to Ist2, In addition, the selectivity of the reaction was improved. The isotopic labeling experiment showed that the carbonyl oxygen in the ketone product originated from oxygen. The electron paramagnetic resonance (EPR) experiment showed that the oxidation reaction was carried out by free radical mechanism. The benzyl pyridine group was selected. The complex of 6-dihydro-5H-cyclopentyl [b] pyridine and 2-ethylpyridine were used as the reaction substrates. The method of oxidation of pyridine side chain C-H bond to ketone catalyzed by Mn(OTf)2 was studied in the yield of 31-88. This method uses 65% hydrogen peroxide solution of environmental protection oxidant) instead of CrO3.The method reported in the literature uses H _ 2SO _ 4-HOAc as solvent, which not only pollutes the environment but also corrodes the equipment seriously. This method uses H _ 2O as solvent. The above problems have been solved thoroughly. The structure of 6o 7-dihydro-5H-cyclopentyl [b] pyridyl [b] pyridyl 5-one has been proved by single crystal X-ray diffraction. The complexes of Mn(NO_3)_2 and 1O10-phenanthroline have been calcined in nitrogen atmosphere to prepare a variety of MnOx-Nx-Nappa Con, and benzyl benzyl has been selected. Pyridines and 6-dihydro-5H-cyclopentyl [b] pyridine as reaction substrates, The oxidation of pyridine side chain C-H bond to ketone catalyzed by MnO_x-N@C was studied. The yield was 38-95. It was found that the catalytic activity of MnO_x-N@C(600 鈩，

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