【作者】 魏晋；

【导师】 陈河如；

【作者基本信息】 汕头大学 ， 无机化学， 2009， 硕士

【摘要】 本文以有机小分子L-脯氨酸和4-羟基-L-脯氨酸催化甲基/硝基取代苯甲醛和丙酮/丁酮之间的不对称直接Aldol反应作为模型,得出如下结论:1.底物取代基的电子效应、位阻效应对反应速率、产率和立体选择性(ee值)的影响。当L-脯氨酸催化Aldol反应时,强吸电子的硝基取代的苯甲醛比供电子的甲基取代的苯甲醛反应要快得多,相应产物的产率要高,但两类产物的ee值差别不是很大,这些与底物苯环上取代基的电子效应有关。同一取代基在底物苯环上位置不同时对反应有影响,对硝基苯甲醛参与反应时速度最快,而且产物的产率最高。邻硝基苯甲醛参与反应时其速度最慢,但其产物的产率要高于间位底物所对应产物的产率。2.丁酮参与反应的区域选择性:具有区域选择性的丁酮与取代苯甲醛间的Aldol反应,丁酮中位阻较小的甲基碳原子对取代苯甲醛羰基碳原子亲核加成,得到取代基较少的β-羟基酮类化合物。3.不同催化剂对同一反应的催化差异:就产率而言,除了对甲基苯甲醛与丙酮间的反应,4-羟基-L-脯氨酸并没有表现出比L-脯氨酸更好的结果。在4-羟基-L-脯氨酸催化的Aldol反应中,借助于氢键形成的三环骨架中间体的烯胺双键碳原子对醛基碳原子立体专一的亲核加成并未受到4位羟基的影响,由其催化的Aldol反应的产物的ee值与L-脯氨酸催化的同一反应产物相比变化不大。因此,催化剂的这种修饰意义不大。在此基础上,我们用L-脯氨酸催化甲基/硝基取代苯甲醛和丙酮(升高温度和减少酮的量)之间的Aldol缩合反应,其产物α,β不饱和羰基化合物与芳胺通过Doebner-VonMiller反应合成喹啉类化合物,产率不足5%,反应的最佳条件有待于进一步提高。实验结果发现:具有吸电子取代基的苯甲醛和苯胺生成的西弗碱在溶于二氧六环的HCl催化下和至少有两个α氢原子的羰基化合物反应可以生成喹啉类化合物。更多还原

【Abstract】 In this paper,the asymmetric Aldol reactions between benzaldehydes derivatives(substituted by methyl or nitro)and acetone/butanone catalyzed by small organic molecules(L-proline and 4-hydroxy-L-proline) were chosen as model reactions,several conclusions are drawn as following:1.Electronic effect and position effect of substituent group in substrate influenced the reaction rate、yield and the ee value.When L-proline was used as the catalyst,benzaldehydes with strong electron-withdrawing groups like nitro react faster than those with electron-donor groups like methyl.The yield of former reaction is also higher than the latter one.But the ee values of both reactions are almost the same. This is related to electronic effect of substituent groups connected to phenyl.Different positions to phenyl of the same substituent group’s also have affects on reactions: 4-Nitrobenzaldehyde reacts faster and gets higher percentage of the products.The reaction rate participated by 2-Nitrobenzaldehyde is slower,but the yield of its product is higher than that by 3-Nitrobenzaldehyde.2.When butanone reactions with benzaldehydes,the reactions display regionselectivities. Position 1,which is less hindrance and forms kinetic enamine,is prefer to invole in the reaction.Less substitutedβ-hydroxy- ketone are obtained.3.Effects of different catalysts on the same reaction have also been investigated. Except the Aldol reaction between p-tulualdehyde and acetone,the yield of all the other reaction catalyzed by L-proline is higher than those catalyzed by 4-hydroxy-L -proline.In the Aldol reactions catalyzed by 4-hydroxy-L-proline,the 4-hydroxy group does not contribute to the stability of the tricycles transitional state.This consist with the fact that the ee value of Aldol product catalyzed by 4-hydroxy-L -proline is almost the same to that catalyzed by L-proline.It is concluded that modification on L-proline with 4-hydroxy group has unconspicuous significance.Based on this foundation,we used L-proline to catalyze the Aldol condensation reaction(under the conditions of rising temperature and reducing the quantity of ketones) between benzaldehydes(substituted by methyl or nitro) and acetone.The products,a,β-unsaturated ketone can react with aniline to produce quinolines via a process similar to Doebner-VonMiller reactions,but the yield is less than 5%. Further improvements need to be carried on to optimize the reaction.The results indicated that the Schiff’s base produced by benzaldehydes with electron-withdrawing substituent group and aniline can react with ketones having at lest two a H to produce quinolines under the catalysis of HCl solving in dioxane.更多还原