【作者】 章维华；

【导师】 蒋木庚；

【作者基本信息】 南京农业大学 ， 农药学， 2010， 博士

【摘要】 香豆素(coumarins)类化合物广泛分布于伞形花科等很多高等植物以及微生物代谢产物中,其生理活性丰富多样,如具生长调节、光敏作用、抗菌抗病毒、利胆解痉、抗凝血、肝毒性、辐射防护及降血糖作用等；具有优异的荧光活性,可作荧光显色剂、荧光探针及非线性光学材料。长期以来,新香豆素类衍生物合成及生物活性、光学特性的研究在医药、光学材料等前沿领域,一直非常活跃。基于对香豆素类化合物的丰富多样的生物活性,尤其是抗菌活性的思考,本论文旨在以具抗菌活性的天然香豆素为一级先导物,通过分子设计、结构修饰,合成多系列香豆素类化合物,同步进行常见农业病菌活性筛选,通过结构与活性的关系分析,优化结构修饰与合成,寻找高抗菌活性的新型香豆素先导分子。1.由不同取代酚与乙酰乙酸乙酯或d1-苹果酸,通过Pechmann缩合反应制备了8种香豆素化合物,再经相转移催化Williamson反应合成相应衍生新化合物35个,结构均经IR, MS,1H-NMR表征得以证实。此部分化合物可分为三类,伞型酮和4-甲基伞型酮及其衍生物；7-甲基或8-甲基香豆素及其衍生物；氯代香豆素类化合物。对Pechmann缩合反应进行了较深入的试验研究,特别是对吡喃环4-位无取代的香豆素母体化合物的制备。此类化合物须由取代酚与dl-苹果酸进行缩合,传统方法时间反应长、酸用量大,且产率很低。通过较系统的试验研究,建立了以微波辐射促进反应体系,减少了质子酸的用量,反应时间大大缩短,产率亦有较明显提高。对相转移催化Williamson反应亦进行了优化试验,建立了此反应的最佳反应体系。2.4,7-二羟基香豆素及其衍生物的合成以间苯二酚和氰基乙酸为原料,经Pechmann反应、水解制备了4,7-二羟基香豆素,再经选择性醚化反应合成了7-羟基-4-甲氧基香豆素和4-乙氧基-7-羟基香豆素。再由7-羟基-4-甲氧基香豆素和4-乙氧基-7-羟基香豆素经相转移催化Williamson反应合成4,7-二羟基香豆素的衍生物。共合成了2个系列的20个新的4,7-二羟基香豆素衍生物,中间产物及目标产物结构经IR, MS,1H-NMR表征得以证实。结构通式如下：对关键中间体4,7-二羟基香豆素的合成路线和反应条件进行了深入研究,筛选出了较佳反应路线和实验条件。对Williamson反应从温度、时间、原料配比、催化剂及用量等各因素进行了优化试验,筛选出了最佳实验条件。3.苯环C-烯丙基取代的香豆素化合物的合成香豆素母体结构中苯环或吡喃环上不同取代基对其生物活性有导向性影响,而很多天然活性香豆素化合物在苯环或吡喃环上有烃基侧链,尤以不饱和侧链为多,故研究如何向母体引入烃基侧链,特别是不饱和侧链的合成方法很有意义。本论文设计的目标化合物之一——C-烯丙基香豆素化合物,采用了如下合成路线：由7-羟基香豆素类化合物先通过Williamson反应制备7-烃氧基香豆素衍生物(O),化合物0通过反应可得到C-烯丙基香豆素化合物(A)。Claisen重排反应是此项研究内容的关键。经典Claisen重排反应的条件苛刻,效率很低,产品难处理,产率一般较低(多数不到50%),很多反应还存在位置选择性问题(邻位与对位取代的竞争)。本论文对不同取代的O-烯丙基化合物进行深入试验研究,合成了8种C-烯丙基取代香豆素,结构均经IR,MS,41H-NMR表征得以证实。对各化合物的合成反应通过改变溶剂及催化剂等条件进行优化实验,提高反应效率及反应的化学选择性。建立了微波促进O-烯丙基香豆素Claisen重排反应的新方法,在强极性质子性溶剂乙二醇中,通过微波间歇式加热,反应产率有较大提高,后处理简便,是7-烃氧基香豆素化合物进行Claisen重排反应的较好反应模式。4.苯环C-异戊烯基取代香豆素衍生物的合成相对烯丙基,异戊烯基侧链在在天然活性香豆素化合物的结构中更为普遍,而在化学合成中,向苯环或吡喃环上引入异戊烯基侧链更困难,国内外医药、天然化学等领域中类似研究领域均没有解决此难题。本论文采用了多种方法进行异戊烯基香豆素的合成,如金属催化偶联、碱性介质中直接取代、催化直接取代等,合成了四种C-异戊烯基取代香豆素,结构均经IR,MS,1H-NMR表征得以证实。5.生物活性研究采用菌丝生长速率法和浊度法测定了合成的香豆素化合物对水稻纹枯病菌,小麦赤霉病菌,番茄灰霉病菌,辣椒疫霉病菌和番茄早疫病菌等五种常见植物病原菌的毒力(4,7-二羟基衍生物的生物活性实验所用植物病原菌除上述五种外,增加了水稻白叶枯病菌)。50mg/L试验浓度下,大多数测试化合物对几种供试病菌均有不同程度的抑制作用,且对水稻纹枯病菌的抑制活性最为明显。4-甲氧基香豆素衍生物明显例外,此类化合物整体对番茄灰霉病菌活性最高。化合物lc、If、2c、3c、3f、6c、 A-6、 P-1-1-a和PM-1-a对水稻枯纹病菌的抑制率均在85%以上,化合物1c、3d、7和A-7对小麦赤霉病菌的抑制率均在80%左右,化合物10b对水稻白叶枯病菌抑制率达到90%,初步表现出了良好的生物活性,有进一步深入研究的价值。更多还原

【Abstract】 Coumarins (or benzopyrones) are widely exisiting in Nature. A large member of coumarins, of natural and synthetic origin, shows excellent biological activities, such as inhibitory of platelet aggregation, antibacterial, anticancer, inhibitory of steroid reductase and inhibitory of HIV-1protease. Coumarins are also used as food additives, optical brightening agents in cosmetics, dispersed fluorescent, and laser dyes. Therefore, various researchs of coumarin derivatives have attracted considerable interest.The biological activities of coumarins brighly depend on their substitution pattern. For example,7-hydroxycoumarin exhibits antioxidant properties and cytostatic, antibacterial, antiviral, xanthine oxidase inhibitor, antihyperglycemic, casein kinase inhibitor activities. To search for new coumarins with antibacterial activities and to investigate structure-activity relationships, synthesis of some novel hydroxycoumarin derivatives and their antibacterial activities were studied in this work.1. Synthesis of hydroxycoumarins and their derivativesEight hydroxycoumarins were synthesized by Pechmann condensation from variously substituted phenols with ethyl acetoacetate or d,l-malic acid. Thirty five new derivatives of those hydroxycoumarins were obtained from these hydroxycoumarins via Williamson reaction. Structures of all the synthetic coumarins were confirmed by IR, NMR and MS. These coumarins can be classified as three types as follows:umbelliferone derivatives7(8)-methylcoumarins coumarin chloridesCoumarins can be synthesised using various methods including Perkin, Pechmann, Knoevenagel, Reformatsky and Wittig reactions. Among these, the Pechmann reaction was widely applied starting from very simple starting materials, and provided good yields of variously substituted coumarins. Condensation of substituted phenols with β-keto esters in the presence of an acid afforded4-substituted coumarins.A major content in this work focuses on the synthesis of hydrocoumarins without C-4 methyl group. These coumarins could be prepared via Pechmann condensation with d,l-malic and phenols. However, this method shows some disadvantages, such as severe reaction conditions, low yield of products, and hard purification. To overcome these shortcomings, new reaction conditions under microwave irradiation were developed as follows:microwave power240W, reaction time30s×5, cone. sulfuric aicd, substituted resorcinols and d,l-malic aicd (1:1.2), the yields were in the range of52%-70%.The Williamson reactions were carried out in acetone and catalyzed by tetrabutylammonium bromide (TB AB) as a phase transfer catalyst in presence of KI. The optimized conditions of Williamson reaction were as follows:n(hydroxycoumarin):n(alkyl halid):n(K2CO3):n(TBAB)=1.0:1.5:2.5:0.1,60℃-100℃for4h-17h, the yields were in the range of60%-93%.2. Synthesis of4,7-dihydroxycoumarin and its derivatives4,7-Dihydroxycoumarin was synthesized from resorcinol and cyanoacetic via Pechmann reaction followed by hydrolysis in31%yield.7-Hydroxy-4-methoxycoumarin and4-ethoxy-7-hydroxycoumarin were synthesized from4,7-dihydroxycoumarin. Twenty new coumarin derivatives from these two hydroxycoumarins were synthesized via Williamson reaction. The optimized conditions of Williamson reaction were:n(7-Hydroxy-4-methoxycoumarin) or n(4-ethoxy-7-hydroxycoumarin):n(alkylhalides):n(anhydrous potassium carbonate):n(TBAB)=1:1.5:2.5:0.1, reaction in DMF at60-80℃for10-27h. Structures of all synthsized coumarins were confirmed by IR, NMR and MS. These coumarins can be classified into two types as follows:3. Synthesis of C-alkyl coumarinsMany coumarins having C-alkyl substituent at benzene ring exhibit a conducting effect on biologicakl activities. The side chain of C-alkyl is also very important to the activitiy. These interesting properties make C-alkyl coumarins very interesting targets. However, synthesis of these coumarins is very difficult. At present, Classien rearrangement is frequently used as a general means to prepare C-alkyl coumarins from O-alkyl coumarins, because O-alkyl coumarins can be easyly synthesized. The synthesis route of these targets is summarized as below.Considering the main drawbacks of this method such as using excess toxic solvents, high temperatures, low yields of products and long reaction times (24h and more), a new synthesis under microwave irradiation was employed proposed in this work. Using this, the rearrangement reaction could be completed in10-15min with the yields of42%-75%. Eight C-alkyl coumarins were obtained, their structures were confirmed by IR, NMR and MS.4. Synthesis of C-prenyl coumarinsC-Prenyl side chain of natural coumarins with biological activities is more commonly observed than other C-alkyl derivative. So, attachment of C-prenyl substituent to coumarins is crucial. Unfortunately, there is no effective way to introduce C-prenyl substituent into the skeleton of coumarin yet. Many methods had been attempted in this paper, and four C-prenyl coumarins were synthesized in low ylieds. All structures of the C-prenyl coumarins were confirmed by IR, NMR and MS.5. Study of antibacterial activitiesThe antibacterial activities of some synthesized coumarins against Rhizoctonia solani, Gibberella zeae, Botrytis cinerea Pers, Phytophara capsici and Alternaria solani were evaluated (besides,4,7-dihydroxycoumarin against Xanthomonas oryzae pv. Oryzae was also tested). The preliminary bioassay showed that most of the coumarins (in a concentration of50mg/L) were active against those plant fungus pathogens, and some of them exhibited satisfactory antibacterial activities against Rhizoctonia solani, Fusarium graminearum or Xanthomonas oryzae pv. Oryzae.Compounds1c、1f、2c、3c、3f、6c、 A-6、 P-1-1-a and PM-1-a exhibit potent activity against Rhizoctonia solani with inhibitory rates of85%～94%. Compounds1c、3d、7and A-7showed satisfactory antibacterial activities against Rhizoctonia solani with80%inhibitory rate.4-Methoxy-7-ethoxycoumarin presents the most potent antibacterial activities against Xanthomonas oryzae pv. Oryzae with a inhibitory rate of90%.更多还原