Toward the Total Synthesis of Onchidin,a Cytotoxic Cyclic Depsipeptide from a Mollusc

The total synthesis of onchidin ( 1 ), a cytotoxic, C₂‐symmetric cyclic decadepsipeptide from a marine mollusc, according to the published structure, is described. A novel β‐amino acid, (2S,3S)‐3‐amino‐2‐methyl‐7‐octynoic acid (AMO), was efficiently prepared in high yield with high diastereo‐ and enantioselectivity based on a catalytic asymmetric three‐component Mannich‐type reaction with a chiral zirconium catalyst. The formation of sterically unfavorable N‐methyl amide and hindered ester bonds were successfully demonstrated, and final macrocyclization was achieved at a secondary‐amide site. Completion of the synthesis of 1 suggested that a revision of the structure of the natural product is required. Two diastereomers were also synthesized as candidates for the actual structure of onchidin. Furthermore, efficient solid‐phase methods were employed for the combinatorial synthesis of other derivatives to clarify the real structure of onchidin. The solid‐phase assembly of a pentadepsipeptide containing all the building blocks was established followed by dimeric cyclization in solution.     

天然环酯肽Obyanamide的全合成

针对目标化合物Obyanamide的结构特征, 运用反合成设计, 将其切为四个合成片断: N-甲基缬氨酸-N-甲基苯丙氨酸二肽(片断A)、噻唑酸衍生物(片断B)、L-乳酸衍生物(片断C)和β-氨基戊酸衍生物(片断D), 并对各个合成片断进行了合成, 最终顺利完成了对天然海洋环酯肽Obyanamide的全合成. 其化学结构经¹H NMR, ¹³C NMR, HMBC以及HRMS (FAB)予以确证.     

Synthesis of Cytotoxic Palmerolides

The chemical synthesis of the palmerolides is the subject of this review. The palmerolides are a family of Antarctic marine natural products, many of which display potent and selective cytotoxicity against melanoma cells. The confluence of promising bioactivities, limited natural supplies, and complex structures makes the palmerolides exciting targets for chemical synthesis. To date, several approaches have been reported, and a consensus strategy based on convergent fragment assembly has emerged. Collective wisdom from myriad approaches reviewed here may enable hybrid strategies capable of delivering larger amounts of synthetic palmerolides to support continued biological studies. Considering the relative lack of options for melanoma chemotherapy and the intriguing activity profile of the palmerolides, efforts aimed at developing an efficient, gram‐scale synthesis of palmerolide A and congeneric structures should be given a high priority.     

Total Synthesis of (−)‐Apratoxin A, 34‐Epimer,and Its Oxazoline Analogue

A concise and convergent total synthesis of the highly cytotoxic marine natural product apratoxin A is accomplished by an 18‐step linear sequence. The high sensitivity of the thiazoline, bearing an adjacent β‐hydroxyl group at the C35‐position, results in the assembly process requiring the inclusion of appropriate protecting groups and the careful optimization of all individual transformations. In the synthesis of 3,7‐dihydroxy‐2,5,8,8‐tetramethylnonanoic acid (Dtena), the three reagent‐controlled asymmetric reactions enables us to introduce four chiral carbon centers in a dihydroxylated fatty acid moiety. Formation of the hindered ester and sterically‐unfavorable N‐methylamide bonds were successfully demonstrated. The thiazoline in apratoxin A was constructed by Tf₂O and Ph₃PO‐mediated dehydrative cyclization, and final macrocyclization was achieved between N‐methylisoleucine and proline residues. Moreover, an oxazoline analogue and a C34 epimer of apratoxin A have also been elaborated in a similar approach. This synthetic route would enable assembly of other analogues differing in stereocenters of Dtena and their amino acids.     

Total synthesis and reassignment of stereochemistry of obyanamide

The total synthesis of a marine cytotoxic cyclic depsipeptide obyanamide is reported. The synthesis has led to a reassignment of the C-3 configuration in β-amino acid residue. And this revision is also supported by biological test.     

Arenicolsterol A，来自海洋环节动物海蚯蚓中的一种新的细胞毒性烯醇式磺化甾醇

Marine organisms are the important source of the bioactive metabolites. A novel enolic sulfated sterol, arenicolsterol A, has been isolated from a marine annelid Arenicola cristata collected in the coast of Mainland of China.The structure was elucidated using all sorts of spectroscopic data including ESIMS, 1D and 2D NMR etc. The cytotoxic bioactivity of this sterol was evaluated by MTT assay. It could inhibit the growth of human cervix cancer cell line (Hela) and human non-small cell lung cancer cell line (NCI-h6) with IC50 of (3.1 0.6)μg/mL and (7.6 0.8)μg/mL.     

Preparation and Application of a Chemical Probe for Identifying the Targets of the Marine Cyclic Peptide Kapakahine A

Marine organisms are a rich source of bioactive secondary metabolites. Although many marine natural products with bioactivities have been isolated, successful elucidation of their mechanisms of action remains limited. In this study, we prepared a probe molecule based on the marine cyclic peptide kapakahine A (1) by introducing a linker with an azide terminal group, which enables the introduction of fluorescent groups for the effective monitoring of subcellular localization, or coupling to affinity beads for the pull-down of target proteins. The results of LC/MS/MS measurements, ProteinPilot analysis, and Western blotting suggest that kapakahine A interacts with the mitochondrial inner membrane proteins PHB1, PHB2, and ANT2, which is consistent with the results of the subcellular localization analysis using a fluorescent probe.     

天然海洋环酯肽Stereocalpin A中间体的合成

以D-苯丙氨酸为原料,经过硼氢化钠/碘还原后与三光气在碱性条件下环合得到Evans手性助剂(R)-4-苄基-2-噁唑烷酮(2),然后将其与丙酰氯缩合,经过LDA偶联、反式Aldol等反应,合成了天然环酯肽StereocalpinA中含有的独特结构片段,该片段对3种人实体瘤细胞系(HT-29,B16/F10,HepG2)具有中等细胞毒性,总收率为30.6%。结果表明,合成路线简便可行,反应产率高,立体选择性好。是制备该化合物的有效途径。     

Total Synthesis of N-Methylsansalvamide A

Sansalvamide A is a cyclic depsipeptide, isolated from a marine fungus of the genus Fusarium by Belofsky in 19991. The depsipeptide displays cytotoxic and antiviral activities, and also possesses inhibitor of MCV topoisomerase2. The corresponding amide de…     

Synthesis and Pharmacological Studies on a Cyclooligopeptide from Marine Bacteria

A natural proline‐rich tetrapeptide cyclo‐prolyl‐leucyl‐prolyl‐phenylalanyl was prepared employing solution‐phase method of peptide synthesis through coupling of dipeptide fragments Boc‐l‐Pro‐l‐Leu‐OH and l‐Pro‐l‐Phe‐OMe which utilizes diisopropylcarbodiimide (DIPC) as coupling agent and N‐methylmorpholine (NMM) as the base. Deprotection of linear tetrapeptide unit followed by its cyclization provided a cyclopeptide, identical in all aspects to the natural molecule. Pharmacological evaluation showed cytotoxic, antifungal and antihelmintic potential of synthesized peptide against Dalton's Lymphoma Ascites (DLA) and Ehrlich's Ascites Carcinoma (EAC) cell lines, pathogenic dermatophytes and earthworms.     

天然产物Kinsenoside的全合成研究

以5-(R)-[(1R，2S，5R)-孟氧基]-2(5H)-呋喃酮为关键手性合成子，完成了具有抗高血脂活性的天然产物kinsenoside的全合成研究。     

Brazilin类似物的合成

以3-(3,4-二甲氧苯基)丙酸为原料, 经分子内傅-克反应、双羟基化、Lombardo 反应, 高价碘的氧化及类Pinacol重排等共10步反应, 完成了brazilin类似物的合成.     

三甲基溴代硅烷促进的非环状与环状缩醛(酮)的合成

以三甲基溴代硅烷作为反应促进剂, 在室温和原甲酸酯或原乙酸酯存在的条件下, 利用醇、二醇处理羰基化合物, 高收率地实现了一系列非环状与环状缩醛(酮)的合成. 产物结构经1H NMR、元素分析等进行了表征.     

环状多聚二硫醚化合物的合成及初步生物活性研究

通过二硫醇化合物氧化的方法合成了8个具有环状结构的多聚二硫醚化合物. 得到的化合物经IR, ¹H NMR, ¹³C NMR和HREIMS确证其结构, 部分化合物还经晶体X衍射方法验证. 通过对II型糖尿病靶标蛋白酪氨酸磷酸酯酶(PTP1B)抑制活性的分析, 发现一些化合物具有一定的PTP1B抑制活性.     

Towards the synthesis of [15]-membered stevastelins through the 2,3-epoxy analogues

A synthetic approach to the [15]-membered stevastelins, a novel class of immunosuppressant agents, is reported based on a macrolactamization route to the 2,3-epoxy derivative 6. The synthesis of this compound was achieved via a stereoselective epoxidation of the allylic alcohol 13, followed by a coupling reaction with a variety of peptide derivatives to give the epoxy peptides 7-10. After an extensive study of cyclizations with these precursors, the best result was achieved with the macrolactamization of 8 in the presence of DEPC, to obtain the epoxy cyclic depsipeptide 6 in 42% yield. From this product, an epoxy analogue of stevastelin B, compound 27, was prepared. Finally, the synthesis of the natural product was attempted through the opening of the oxirane ring contained in 6 and 26, with a variety of methyl cuprate reagents, but without success.     

Design,Synthesis, and Cytotoxic Activity of Novel Natural Arylsulfonamide-Inspired Molecules

Primary arylsulfonamide functional groups feature prominently in diverse pharmaceuticals. However, natural arylsulfonamides are relatively infrequent. In this work, two novel arylsulfonamide natural products were first synthesized, and then a series of novel molecules derived from natural arylsulfonamides were designed and synthesized, and their in vitro cytotoxic activities against A875, HepG2, and MARC145 cell lines were systematically evaluated. The results indicate that some of these arylsulfonamide derivatives exhibit significantly good cytotoxic activity against the tested cell lines compared with the control 5-fluorouracil (5-FU), such as compounds 10l, 10p, 10q, and 10r. In particular, the potential molecule 10q, containing a carbazole moiety, exhibited the highest inhibitory activity against all tested cell lines, with IC₅₀ values of 4.19 ± 0.78, 3.55 ± 0.63, and 2.95 ± 0.78 μg/mL, respectively. This will offer the potential to discover novel drug-like compounds from the sparsely populated area of natural products that can lead to effective anticancer agents.     

An Expeditious Route for the Total Synthesis of Pondaplin Isolated from Annona glabra

A novel cyclic prenylated phenylpropanoid, pondaplin 1, was first synthesized in 26% overall yields through an expeditious route (7 steps) that employed highly regio- and stereoselective phenyltellurenylation to arylacetylene and palladium (Ⅱ) chloride-catalyzed carbonylation of hydroxy styryl phenyl telluride as key steps.     

氯化亚锡催化合成环缩醛

通过正交实验确定了氯化亚锡催化合成正丁醛缩1,2-丙二醇的最佳工艺条件为：正丁醛200mmol,n（正丁醛）：n（1,2-丙二醇）=1．0：1．5,氯化亚锡3g,环己烷13mL,回流分水1h,收率76．35％。并在此条件下合成了多种环缩醛,收率62．18％～81．90％。催化剂可重复使用。