喜树碱衍生物的合成研究进展

目前有不少关于对喜树碱分子结构改进和修饰的报道，许多高活性的喜树碱衍生物相继问世。其中，10-经基喜树碱、拓普替康、伊立替康以及9-氨基、9-硝基喜树碱、7-乙基-10-羟基喜树碱等在临床显示了广泛的抗癌活性。本文综述对喜树碱衍生物的一些最新合成进展。参考文献19篇。     

喜树碱结构与活性的关系

喜树碱是从我国特有植物喜树中分离得到的。它是一种广谱抗癌药物，对多种肿瘤有疗效，但同时也有副作用。为了寻找一种既具抗癌活性，毒性又小的喜树碱类似物，国外学者对喜树的五个环分别进行了修饰，并对修饰产物进行了药理研究，找到了抗癌活性与结构之间的关系。本文着重介绍他们的研究结果并简要总结一下喜树碱的结构、性质。     

抗癌药物喜树碱的功能化改性及研究进展

20-（S）-喜树碱（CPT）是一种具有广谱抗癌活性的生物碱。其抗癌活性主要体现在CPT的内酯环能够与DNA拓扑异构酶Ⅰ结合并异化DNA拓扑结构,进而诱导肿瘤细胞的凋亡。然而,喜树碱内酯环在生理环境下极易水解开环形成羧酸盐,导致药物失活;同时喜树碱本身所存在的水溶性差、对正常机体组织毒副作用大等缺点也极大限制了CPT的...     

高效液相色谱-质谱联用方法分析植物愈伤组织中的喜树碱及其衍生物

喜树(Camptotheca acuminate Decne)为山茱萸目(Comales)珙桐科(Nyssaceae)植物，落叶乔木。广泛分布于我国长江流域及西南各省和印度部分地区，资源丰富。Hisang等发现喜树碱作为一种拓扑异构酶Ⅰ的抑制剂具有抗癌活性，目前，喜树碱已成为临床治疗中广泛使用的抗癌药。人们对喜树碱抗癌药物需求增加，人们开始偿试利用植物细胞培养的方法生产喜树碱。     

(Z)-1-[2-(苯基溴氯化锡基)乙烯基]-1-环己醇的晶体结构和反应机理

有机锡化合物的抗癌活性与结构的关系是人们所关注的一个重要课题[1.2].自1989年以来,我们合成了几个系列的C-Sn直接相连并在分子中存在O→Sn内配位的有机锡化合物[3]．经过抗癌活性实验,发现其中有很多种具有较高的抗癌活性．本文所报道的标题化合物分子有两种构型,迄今为止未见类似的报道．标题化合物的抗癌活性正在测试中．1实验部分1．且仪器1106型元素分析仪;锡含量用重量法分析;NicoletR。M／E四圆衍射仪．1．2标题化合物的合成（Z）－l｛2－（二苯基演化锡基）乙烯基11一环己醇（I）按照文献［"方法合成．产率80％,m．卜14…     

天然抗癌药物--喜树碱及其衍生物的研究进展

本文就天然抗癌药物－喜树碱及其衍生物的发展状况,抗癌机理及应用前景等作了综合评述,引用文献30篇。     

高喜树碱的合成研究进展

目前文献报道的高喜树碱合成方法主要是半合成和全合成两类,前者方法简单、便捷,但取代基种类太少,而且扩环后只能得到消旋的高喜树碱。后者虽然方法复杂,但可以在A环和B环上引入各种需要的取代基,目标分子丰富,并且能进行不对称合成。本文概述了近年来国内外高喜树碱的研究现状,对各个研究小组的研究成果进行了较深入的介绍,并对他们的合成方法做了分类梳理。另外,展望了高喜树碱在医药领域的发展前景,为今后研究指明了发展方向。     

喜树碱环磷酸酯前药的合成研究

为了提高抗肿瘤药物喜树碱的靶向作用,设计并合成了一种喜树碱的环磷酸酯前药。以间氯苯乙酮为起始原料,经过缩合、还原反应,制备了1-间氯苯基-1,3-丙二醇(2),研究了反应温度对缩合反应的影响。将其与对硝基苯二氯磷酸酯反应合成了制备环磷酸酯前药的重要中间体1-间氯苯基-1,3-丙基环磷酸酯(3),再以10-羟基喜树碱为底物,与中间体3合成了目标化合物喜树碱环磷酸酯前药(4)。探讨了两种催化剂对目标产物喜树碱环磷酸酯前药合成反应的影响,结果表明,叔丁基氯化镁催化效果较好,反应时间缩短到24 h,产物收率42.5%。中间体及产物结构经~1H NMR表征。     

10-羟基喜树碱氨基酸缀合物的合成及抗肿瘤活性研究

以10-羟基喜树碱为原料,通过两碳边链链接,合成了一系列10-羟基喜树碱氨基酸缀合物和9-硝基-10-羟基喜树碱氨基酸缀合物.采用CCK-8法测试了合成化合物体外对人口腔鳞癌细胞KB、人肝癌细胞HepG2和小鼠结肠癌细胞C26三组细胞株的增殖抑制活性,结果表明部分目标化合物对所选肿瘤细胞株显示了潜在的抑制活性,其中10-羟基喜树碱氨基酸缀合物的体外活性明显优于9-硝基-10-羟基喜树碱氨基酸缀合物的体外活性.     

抗癌植物喜树化学成分的研究 Ⅳ.11-羟基喜树碱等化学成分的分离鉴定

从喜树果中又分离出五种化学成分,用光谱及化学方法鉴定为11-羟基喜树碱(1),10-甲氧基喜树碱(2),脱落酸(3),丁香脂素(4)和β-谷甾醇.1为新生物碱,动物试验表明1,2均有明显的抗癌作用.     

单萜吲哚生物碱的仿生合成

单萜吲哚生物碱因其骨架和官能团的丰富变化,加上它们的生物活性,多年来 一直哟引着一代又一代的化学家对其进行结构和合成研究,它们的共同生物合成前 体strictosidine是由色胺和单萜苷secologanin缩合形成的。自从secologanin可 以大量得到以后,以它为原料沿着可能的生物合成路线合成天然生物碱即仿生合成 就成为一个重要的研究领域。它对于理解和阐释生物碱的生物合成过程,为提供天 然来源极少的生物碱供药理试验及对促进有机合成化学的发展等都是有重要意义。 这方面的研究也取得了许多重要进展,成功合成了一些重要的单萜吲哚生物碱,如 育亨宾类、钩藤碱、异钩藤碱、卡得宾、利血平类似物、喜树碱等。     

Preparation of alpha-phosphono lactams via electrophilic phosphorus reagents: an application in the synthesis of lactam-based farnesyl transferase Inhibitors

Conversion of N-alkyl lactams to the corresponding alpha-phosphono lactams has been investigated through procedures that involve formation of the lactam enolate and reaction with a phosphorus electrophile. With N-octylpyrrolidinone, the enolate could be trapped efficiently on oxygen by reaction with diethyl phosphorochloridate, and the resulting vinyl phosphate rearranges smoothly to the desired phosphonate upon treatment with additional LDA. Attempts to apply the same protocol to N-farnesyl lactams met with limited success. Studies with an isolated alpha-phosphono N-farnesyl lactam have shown that the farnesyl group is not stable to the excess of strong base required for rearrangement of a vinyl phosphate. However, a series of N-farnesyl lactams and imides was converted to the desired phosphonates through formation of the lactam enolate, reaction with diethyl phosphorochloridite, and subsequent oxidation of the phosphorus intermediate to the P(V) state.     

On the C-16 configuration of sitsirikine

The indole alkaloid sitsirikine has been synthesised by a biomimetic conversion of strictosidine and its C-16 configuration established as R by cyclisation to a 16,17-dihydroheteroyohimbine.     

Structure-based engineering of strictosidine synthase: auxiliary for alkaloid libraries

The highly substrate-specific strictosidine synthase (EC 4.3.3.2) catalyzes the biological Pictet-Spengler condensation between tryptamine and secologanin, leading to the synthesis of about 2000 monoterpenoid indole alkaloids in higher plants. The crystal structure of Rauvolfia serpentina strictosidine synthase (STR1) in complex with strictosidine has been elucidated here, allowing the rational site-directed mutation of the active center of STR1 and resulting in modulation of its substrate acceptance. Here, we report on the rational redesign of STR1 by generation of a Val208Ala mutant, further describing the influence on substrate acceptance and the enzyme-catalyzed synthesis of 10-methyl- and 10-methoxystrictosidines. Based on the addition of strictosidine to a crude strictosidine glucosidase preparation from Catharanthus cells, a combined chemoenzymatic approach to generating large alkaloid libraries for future pharmacological screenings is presented.     

Photochemical approach to 4,5-dioxoaporphine alkaloids. The total synthesis of pontevedrine

An easy and efficient total synthesis of pontevedrine 14b , a 4,5-dioxoaporphine alkaloid, was achieved for the first time. It is based on the controlled photo-oxidation of the lactam 7c , to give the benzylidene-dioxo compound 13b and its subsequent photocyclizaton. A “one pot” transformation of the lactam 7c into norpontevedrine 14a was also achieved.     

Comparative study of fourteen alkaloids from Uncaria rhynchophylla hooks and leaves using HPLC-diode array detection-atmospheric pressure chemical ionization/MS method

The purpose of the study is to compare alkaloid profile of Uncaria rhynchophylla hooks and leaves. Ten oxindole alkaloids and four glycosidic indole alkaloids were identified using HPLC-diode array detection (DAD) or LC-atmospheric pressure chemical ionization (APCI)-MS method, and a HPLC-UV method for simultaneous quantification of major alkaloids was validated. The hooks are characterized by high levels of four oxindole alkaloids rhynchophylline (R), isorhynchophylline (IR), corynoxeine (C) and isocorynoxeine (IC), while the leaves contained high level of two glycosidic indole alkaloids vincoside lactam (VL) and strictosidine (S). The presented methods have proven its usefulness in chemical characterization of U. rhynchophylla hooks and leaves.     

Enantioselective rhodium-catalyzed [2+2+2] cycloaddition of alkenyl isocyanates and terminal alkynes: application to the total synthesis of (+)-lasubine II

The use of TADDOL-based phosphoramidite ligands on rhodium allows for the incorporation of terminal alkynes in the [2+2+2] cycloaddition with alkenyl isocyanates. Terminal aliphatic alkynes provide bicyclic lactams, while the use of aryl alkynes provides complementary access to vinylogous amides. Product selectivity seems to be governed by a combination of electronics and sterics, with smaller and/or more electron-deficient substituents favoring lactam formation. The use of homologous alkenyl isocyanates leads to an expedient asymmetric total synthesis of the alkaloid lasubine II.     

Novel resolution of chiral lactams

A practical method of resolving chiral lactams, e.g. 1 , has been evolved, based on the hydroxymethylation of the lactam, followed by esterification of the product 2 with an optically active N-protected amino acid derivative, e.g. N-benzyloxycarbonylphenylalanine pentafluorophenyl ester 3 . Chromatographic separation of the unreacted hydroxymethylated lactam 2 and the ester 4 and subsequent dehydroxymethylation of the former and aminolysis of the latter afforded pure enantiomer, (R)- 1 and (S)- 1 .     

Chiroptical studies-part 99: The circular dichroism of seven-membered lactams and lactones

This empirical analysis of CD data for 7-membered lactams includes examples of all twelve possible structural types in which the lactam is fused to a cyclohexane ring as part of a polycyclic compound. The CD behaviour of several classes of lactams shows ‘dOgura's sign rule’ to be an over-simplification. The signs and values of Δ? for lactams in which the second ring is fused at the 3,4- or 6,7-positions of the lactam ring show considerable deviations from the “normal’ values for 4,5- or 5,6-fused lactams.No simple pattern of group contributions emerged from this analysis, but a correlation of CD behaviour with the torsion angle in the C-CO-NH-C structural component is suggested, on the basis of a study of Dreiding models, and is supported by the result of an X-ray crystallographic analysis of one of the lactams.This study of CD data is extended to a smaller group of lactones with a seven-membered ring, most of which show Cotton effects opposite in sign and of smaller magnitude than those of the corresponding lactams.     

Studies dealing with thionium ion promoted mannich cyclization reactions

Treatment of several amido-substituted thioacetals with dimethyl(methylthio)sulfonium tetrafluoroborate (DMTSF) produces synthetically useful thionium ions that are intercepted by the adjacent nitrogen atom to afford both five- and six-membered alkylthio-substituted lactams as transient intermediates. Further reaction of the alkylthio-substituted lactam with DMTSF generates an N-acyliminium ion, which undergoes cyclization with the tethered aromatic ring to produce an azapolycyclic ring system. Related cyclization sequences occur when amido thioacetals possessing simple olefinic tethers were used. The overall procedure represents an efficient one-pot approach toward various nitrogen-containing ring systems. The cyclization reaction was employed for a synthesis of the core skeleton of the erythrina alkaloid family.