【作者】 魏忠林；

【导师】 柏旭； 党群；

【作者基本信息】 吉林大学 ， 有机化学， 2010， 博士

【摘要】 本论文开发了“一锅”合成4-氨基喹唑啉的方法,并基于此方法,以博来霉素家族的成员P-3A为先导化合物,围绕其核心嘧啶环结构进行改造,设计并探索了两类P-3A类似物的合成,并对其生物活性进行了初步测试。第一章介绍了4-氨基喹唑啉的生物活性以及研究现状。并系统的研究了以羧酸和邻氨基苯甲腈为起始物通过“一锅”法合成4-氨基喹唑啉的反应,考察了其反应规律及适用范围。4-氨基喹唑啉是一类重要的含氮杂环,其衍生物具有抗菌、消炎、抗高血压等多种生物活性。这类化合物还具有高选择性酪氨酸激酶抑制活性,表现出良好的抗癌活性。因此,近年来4-氨基喹唑啉的合成受到了药物合成化学家们的广泛关注。4-氨基喹唑啉的合成通常是以邻氨基苯甲酰胺为底物,与甲酸反应形成喹唑酮,然后依次经氯代、胺的取代反应后得到。该方法步骤多,反应底物类型受到一定的限制。“一锅法”合成2-取代-4-氨基喹唑啉也有报道,其中多数是通过羧酸衍生物(如腈、原羧酸酯、酰氯、脒等)与邻氨基苯甲腈或邻氨基苯甲酰胺等关环得到。直接以便宜易得的羧酸为底物,通过“一锅法”合成4-氨基喹唑啉的反应尚未见报道。首先,我们对“一锅”法合成4-氨基喹唑啉的反应条件进行了考察。研究表明羧酸与邻氨基苯甲腈在3.3当量的PPh3-CCl4作用下,以吡啶作碱催化,先在乙腈条件下回流,然后再加入氨的甲醇溶液加热,能够以中等到较高产率得到4-氨基喹唑啉。该方法可适用于各种芳香酸,其中含有吸电子基的苯甲酸产率较高(对氟苯甲酸,产率81%),而带有推电子取代基的苯甲酸会降低产率(对甲氧基苯甲酸,产率30%)。此外,该方法用于脂肪酸也可以得到较好的产率(54-81%),反应规律与脂肪酸电性相关,与该脂肪酸在该反应条件下的稳定性也具有直接关系。包括扁桃酸也可以在该条件下反应,产率54%。同时以苯乙酸与邻氨基苯甲腈的反应为例考察了“一锅”反应与分步反应对产率的影响,结果表明“一锅”反应的产率较高(62%,而分步反应总产率为54%)。同时,考察了羧酸与取代的邻氨基苯甲腈的反应规律,发现带有吸电子取代基的邻氨基苯甲腈会降低反应产率。通过进一步条件考察,找到了应用于保护的氨基酸参与合成2-取代-4-氨基喹唑啉的方法,以较好的产率(69%)得到了N-Cbz-天冬酰胺参与的关环产物。第二章介绍了有关博来霉素抗癌作用的机理及P-3A的合成;尝试了以4-氨基喹唑啉为核心的构象限制P-3A类似物的合成;设计并合成了P-3A噻唑类似物,并测试了其活性。博来霉素(Bleomycin)是临床上广泛应用的一类抗癌药物,是一类结构复杂的糖肽类天然产物。研究表明,博来霉素是通过裂解DNA的双螺旋结构并使其不可被细胞修复来发挥其抗癌作用的。根据其功能,博来霉素分子可分为四个结构功能域:与金属离子络合的DNA裂解功能域、由双噻唑和带正电荷的锍盐组成的DNA络合功能域、增强分子细胞膜穿透性的二糖片段和由二肽构成的桥连片段。其中,DNA裂解功能域是其发挥抗癌作用的关键结构单元。博来霉素结构复杂,合成较为困难。合成博来霉素的关键是合成核心的嘧啶环及其侧链,来构建金属键合功能域。基于此,P-3A可以作为一个理想的最初合成目标。虽然有研究组已经完成了P-3A的全合成,并对其进行了多方面的修饰,考察了构效关系,揭示了产生DNA裂解活性的关键结构及官能团;还有的研究组主要围绕对P-3A分子中嘧啶环核心结构的改造,通过将其替换为吡啶环,研究这些P-3A类似物对金属络合作用的影响开展工作,但对于博来霉素金属健合功能域的研究还是众多研究组所关注的领域,可通过对该部分的修饰改造来寻找具有更好的裂解DNA活性的先导化合物或对其裂解DNA的作用机制进行探索。在已有的博来霉素类似物的研究结果中,替换其核心4-氨基嘧啶环的研究只有Ohno研究组有少量报道,关于利用构象限制策略改造核心嘧啶环的研究尚未见报道。利用4-氨基喹唑啉替换其核心4-氨基嘧啶环可以得到构象限制的博来霉素类似物。我们通过多方面尝试,最终以对甲基苯胺通过五步反应合成2-氨基-3-溴-5-甲基苯甲腈,并以此为原料得到了合成构象限制P-3A类似物的前体。但利用Buchwald偶联和Ullmman-Type偶联反应条件尝试了连接二肽侧链,均没有成功,无法完成构象限制P-3A类似物的合成。通过替换P-3A结构中的嘧啶环为噻唑环,设计并合成了一个P-3A类似物,检测了DNA裂解活性。在结构设计中,保留了博来霉素结构中完整的金属键合功能域中关键官能团,分为三个片段——丝氨酸片段、噻唑环片段、二肽片段——组装合成了P-3A噻唑类似物。在合成过程中,以丝氨酸甲酯盐酸盐为原料,通过三苯甲基保护氨基、Mistunobu反应偶联邻苯二甲酰亚胺、保护基变换、甲酯氨化、脱除邻苯二甲酰亚胺等步骤,合成了具有光学活性的丝氨酸片断——?-氨基丙氨酰胺;以硫代乙酰胺与溴代丙酮酸乙酯关环、溴代得到了噻唑环片段,并以简捷的方式与丝氨酸片断连接;最后,通过肽偶联方式连接了二肽侧链。最终通过一个单线10步反应以25%的总产率得到P-3A噻唑类似物。最后,对该P-3A类似物进行了裂解DNA活性测试,发现在200 ?M具有明显的DNA裂解活性。更多还原

【Abstract】 In this dissertation, a useful method was developed to prepare the 4-aminoquinazoline heterocyclic nucleus, which entails a two-step one-pot procedure leading to 4-aminoquinazolines up to good yields. The application of this method to synthesis of 4-aminoquinazoline bleomycin analogs is envisioned. And a P-3A thiazole analog was designed and synthesized.In Chapter One, biological activity and synthesis of 4-aminequinazoline were reviewed. A new one-pot two-step procedure was developed to prepare 4-aminoquinazolines from carboxylic acids and 2-aminobenzonitriles. Various carboxylic acids, including aromatic, aliphatic, and amino acids, are suitable substrates for this new method.Quinazolines are a family of compounds with a variety of pharmacological properties, such as analgesic, narcotic, anti-malarial, sedative and hypoglycaemic ones. 4-Aminoquinazolines are useful as fungicides and as anti-inflammatory, anti-cancer, anti-microbial and anti-hypertensive agents. 4-Aminequinazolines have not been the object of new synthetic developments in the last few years and recent reports on their preparation use only classical methods via 4-chloroquinazolines, an important synthetic intermediate as they can be derivatised further through nucleophilic attack at the C-4 position. 4-Aminoquinazolines were prepared from 2-aminobenzonitrile with either a nitrile or an orthoester under microwave conditions. Recently, 2-aminonitrile was cyclized with formic acid at the elevated temperature of 200℃leading to 5,6-dihydro-quinazolines; 2-aminobenzamide was cyclized with anilines and orthoesters to give 4-arylaminoquinazolines. But the cyclization with 2-aminobenzonitrile and carboxylic acid were not found.In our study, most benzoic acid gave the desired quinazolines in good-to-high yields. However, para-methoxybenzoic gave lower yield compared to other benzoic acids, and it is possible that the strong electron-donating property of the MeO group reduces the reactivity of the benzoic acid. Heterocyclic aromatic acids were also suitable substrates for this reaction leading to desired quinazolines in moderate yields. Encouraged by the success with aromatic acids, aliphatic acids including N-Cbz-Lasparagine required for the synthesis of bleomycin analogs were studied. Aliphatic carboxylic acids are also suitable for this one-pot two-step reaction leading to 4-aminoquinazolines in good yields. To compare this new one-pot procedure against the conventional stepwise approach, phenylacetic acid was coupled with 2-aminobenzonitrile via its acyl chloride to give 2-N-(phenylacetyl) amino- benzonitrile in 72% yield; the resulting amide was subjected to the new one-pot two-step procedure and give compound in 54% yield. This indicates that preformation of the amide bond did not lead to higher yield of the desired 4-aminoquinazoline. More importantly, N-Cbz-Lasparagine reacted with 2-aminobenzonitrile to give 4-aminoquinazoline in good yield. 2-Aminobenzonitriles with halo groups reacted with either N-Cbz-L-asparagine or phenylacetic acid to give the desired products in moderate yields. The electron-withdrawing effects of the halo groups likely decreased the nucleophilicity of the aniline group, which may account for the observed lower yields.In chapter two, synthetic and mechanistic studies of Bleomycins were reviewed. The design of Bleomycin analogs was described. We got the starting material of Conformation-Restricted P-3A analogs with the one-pot two-step method, and tried to couple the side chain of peptide. A P-3A thiazole analog was designed and synthesized.Bleomycin is a clinically employed antitumor agent through the sequence-selective cleavage of DNA in a process that is both metal-iron and O2 dependent. However, dose-dependent undesired side effects, such as pulmonary toxicity, are limiting the therapeutic efficacy of bleomycins. Thus, it has been suggested that improved bleomycin analogs may have enhanced therapeutic index between anticancer activity and undesired toxicity. Each structural unit of bleomycin A2 contributes importantly to its biological activity: the N-terminal pyrimidine, the metal binding domain, demonstrated that the majority of the DNA binding affinity originates from the C-terminus with the bithiazole and the positively charged sulfonium salt. The role of the carbohydrate domain has been less extensively examined although it is known to enhance biological potency and efficacy.P-3A is a microbial product isolated in biosynthetic studies of the bleomycins, whose structure contains the functionalized pyrimidine core of bleomycin A2 and represents the simplest member of this class of agents. Boger detailed pioneering total syntheses of P-3A, and researched its SAR. Ohno et al. synthesized a serious of P-3A pymidine analogs and got a good biological activity.In medicinal chemistry, conformational restriction is commonly used to improve potency. We envisioned that the application of such a strategy to the metal-binding domain of bleomycin could lead to analogs that promote more efficient formation of the oxygen-Fe(II)-bleomycin complex. To test this concept, P-3A, the smallest member of the bleomycin family but still retaining DNA cleavage properties was selected. Therefore, the cyclization of the carbonyl group onto the 6-position of the pyrimidine nucleus was performed via a benzene ring. The quinazoline ring system should fix the–NH- group in a position that has higher propensity for metal binding compared with the relatively flexible amide group in P-3A and other bleomycins. We envisioned that 2-aminobenzonitrile could react with a carboxylic acid in an one-pot two-step procedure to produce the key intermediate required for our conformation-restricted P-3A analogs, and it can introduce the stereochemistry center with natural amino acid.We synthesized 2-amino-3-bromo-5-methylbenzonitrile via a five-step route, and got the key intermediate compound with it. We tried to couple the side chain of peptide via Buchwald coupling reaction and Ullmman-Type coupling reaction, but failed.In the design of the P-3A thiazole analog structure, the key groups of full metal binding domain in bleomycin structure was remained and P-3A thiazole analog was synthesized with three parts: serine segment, thiazole nuclear and side chain of two peptides. In synthesis routs, the ?-aminoalanine amide was synthesized via protecting amine with trityl, Mistunobu coupling with phthalimide, transforming trityl to Boc, amination of methyl, deporting the phthalimide with hydrazine. Thiazole nuclear was synthesized with ethyl bromopyruvate and ethanethioamide and then linked with serine segment. Finally, it coupled with peptide. We got the P-3A thiazole analog via a ten-step single route with a 25% total yield. And this P-3A thiazole analog can cleave supercoiled DNA at 200 ?M.更多还原