Apoptolidinone A: synthesis of the apoptolidin A aglycone

An efficient stereocontrolled synthesis of apoptolidinone A, the aglycone of apoptolidin A is described. The synthetic strategy relies on a cross coupling between C11/C12 of a northern half (C1-C11) and a southern part (C12-C28) followed by a ring-size selective macrolactonization. Key steps for the introduction of the southern half stereocenters are a stereoselective aldol reaction, a substrate controlled dihydroxylation and a chelation-controlled Grignard/aldehyde addition. The conjugated triene of the northern half was built up successively by E-selective Wittig reactions. L-Malic acid was chosen as the chiral pool source for the C8/C9 stereocenters. The final cleavage of the silyl ethers and the conversion of the C21 methyl ketal into the hemiketal was achieved by HF.pyridine.     

Biosynthetically Inspired Syntheses of Secu′amamine A and Fluvirosaones A and B

Presented here is a concise synthesis of secu′amamine A, and fluvirosaones A and B from readily available allosecurinine and viroallosecurinine. The key C2‐enamine derivative of (viro)allosecurinine, the presumed biosynthetic precursors of these natural products, was accessed, for the first time, by a VO(acac)₂‐mediated regioselective Polonovski reaction. Formal hydration and 1,2‐amine shift of this pluripotent enamine compound afforded secu′amamine A. Formal oxidative [3+2] cycloaddition reaction between this enamine and TMS‐substituted methallyl iodide reagent paved the way to the precursors of fluvirosaones A and B. The relative stereochemistry at the C2 position of these advanced intermediates governs the fate of 1,2‐amine shift leading to fluvirosaones A and B. The syntheses of potential biosynthetic precursors and investigations of their chemical reactivities have provided insights regarding the biogenesis of these natural products.     

A solid-phase total synthesis of the cyclic depsipeptide HDAC inhibitor spiruchostatin A

Spiruchostatin A, a potent histone deacetylase inhibitor, was efficiently synthesized from (3S,4R)-4-amino-3-hydroxy-5-methylhexanoic acid utilizing solid-phase peptide elongation with d-cysteine, d-alanine, and (E)-3-hydroxy-7-thio-4-heptenoic acid and solution-phase macrolactonization, followed by intramolecular disulfide formation.     

The sclerophytin A adventure

The structural designation A originally made by Sharma and Alam to sclerophytin A was considered to be ambiguous and so notably strained relative to B that the latter was targeted for de novo synthesis (Scheme 1). Our two successful routes began with (5S)-(d-menthyloxy)-2(5H)-furanone and involved the application of cycloaddition, Claisen ring expansion, transannular oxymercuration, and 1,2-carbonyl transposition tactics to arrive at B. It was immediately apparent from polarity considerations and spectroscopic data that the antileukemic marine metabolite in question was in need of more deep-seated structural revision. Following close re-examination of an acquired authentic sample by advanced NMR techniques, the strong inference was made that sclerophytin A actually lacked a second oxygen bridge and was in reality the triol C. This conclusion was unequivocally confirmed by diverting an advanced intermediate generated earlier into a short sequence beginning with regiocontrolled dihydroxylation and terminating with configurational inversion at the secondary carbinol center. The status of other members of this series is also presented.     

天然产物骆驼宁碱A及其衍生物的合成研究进展

骆驼宁碱A是从骆驼蒿中分离出来的喹唑啉酮类生物碱, 骆驼蒿在中国民间用来治疗风湿病、炎症、脓肿及其他疾病. 由于骆驼宁碱A的药理活性, 有关其合成方法受到了关注. 综述了该化合物的合成方法, 根据闭环方式的不同把合成方法分为六大类, 大部分方法都围绕中间体喹啉吡咯烷酮的合成, 一般步骤较长, 产率过低, 虽然有的路线步骤短, 产率高, 但原料不易得到. 因此, 经济的产业化方法还有待进一步研究.     

Schinortriterpenoids: A Case Study in Synthetic Design

Since the pioneering days of total synthesis and retrosynthetic analysis, the community has embraced guiding principles for planning synthetic approaches towards complex natural products. These guideposts have enabled the community to synthesize ever more complex compounds by applying prior knowledge gained in new settings. The recently isolated schinortriterpenoid family of natural products has attracted considerable synthetic attention and provided a rich opportunity to evaluate the lessons learned in the construction of complex, polycyclic scaffolds. In this Minireview, a detailed discussion of the synthetic work within this family is provided, including the six reported total syntheses, as well as a comparative analysis of the approaches utilized in their construction.     

A convenient semicarbazide resin for the solid-phase synthesis of peptide ketones and aldehydes

Use of a semicarbazide resin for the solid-phase preparation of peptide ketones and aldehyde led to optimal results in terms of both purity of the final product and overall yield. This resin was prepared without complication by activation of the commercial available aminomethyl polystyrene with CDI at room temperature, followed by treatment with tert-butyl carbazate. Furthermore, the TNBSA colorimetric assay has been adapted for checking the incorporation of the carbonyl moiety onto hydrazine-based resins.     

强剌激性姜样味化合物Yakuchinone-A的简便合成方法

１,７二芳基庚烷类化合物（Ａｒ１Ｃ７Ａｒ２）是从山姜属、姜黄属等药用植物中分离得到结构新颖的一大类天然产物［１,２］．药理研究表明,该类天然产物不仅具有调味作用,而且还具有健胃,抗肝毒,消炎,抗溃疡,抗氧化,杀虫等多种生物活性．Ｙａｋｕｃｈｉｎ...     

微波辅助晶化法合成MCM-22分子筛的研究

开展了微波辅助法合成MCM-22分子筛的研究, 经过29 h微波晶化得到了与传统水热法合成5 d相同的100%晶化的样品, 有效地缩短了合成时间. 通过XRD, SEM, FT-IR, ICP和²⁷Al MAS NMR技术表征, 微波辅助合成样品具有高纯度、均一形貌, Al原子有效进入骨架等特征. 对合成中的关键性条件, 如结构导向剂的含量进行了深入研究, 并给出了可能的合成机理. 此外, 通过在合成液中添加少量高介电损失物质, 进一步缩短了合成时间.     

A Facile Synthetic Approach to Two Chalcones

Some Vitex species have long been used in folk remedies due to their excellent antibiotic activities1. Chalcones also have good activities such as immunological action2. 2? 4?dihydroxy-4, 6?dimethoxy chalcone 1 and 4?hydroxy-4, 2? 6?trimethoxy chalcone 2 were natural products which were firstly separated from the aerial parts of Vitex leptobotrys in North Vietnam by Trinh3. To our knowledge, no synthetic method about these compounds was reported. Herein we report a convenient synthetic r…     

钩吻素子的半合成

钩吻素子(Koumine)的新型笼状结构,引起了人们探讨其生源合成的兴趣。我们研究了从国产钩吻中分离出的7个已知结构的生物碱后,认为钩吻素戊(16-epi-nor-macusineB)可能是钩吻素子的前体。于是我们以手头所有的另一生物碱,老刺木碱(Vobasine)(在结构上与钩吻素戊同属于蛇根精(Sarpagine)类生物碱)为起始原料,先经LiAlH_4还原,再在稀硫酸中以SeO_2/H_2O_2氧化,同时发生骨架重排,完成了钩吻素子的半合成。其可能的机理如图所示:     

A detailed study on understanding glycopolymer library and Con A interactions

Synthetic glycopolymers are important natural oligosaccharides mimics for many biological applications. To develop glycopolymeric drugs and therapeutic agents, factors that control the receptor‐ligand interaction need to be investigated. A library of well‐defined glycopolymers has been prepared by the combination of copper mediated living radical polymerization and CuAAC click reaction via post‐functionalization of alkyne‐containing precursor polymers with different sugar azides. Employing Concanavalin A as the model receptor, we explored the influence of the nature and densities of different sugars residues (mannose, galactose, and glucose) on the stoichiometry of the cluster, the rate of the cluster formation, the inhibitory potency of the glycopolymers, and the stability of the turbidity through quantitative precipitation assays, turbidimetry assays, inhibitory potency assays, and reversal aggregation assays. The diversities of binding properties contributed by different clustering parameters will make it possible to define the structures of the multivalent ligands and densities of binding epitopes tailor‐made for specific functions in the lectin‐ligand interaction. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2588–2597     

First synthesis of (+)-myxothiazol A

First convergent synthesis of (+)-myxothiazol A (1) was achieved based on modified (one-pot) Julia olefination between (3,5R)-dimethoxy-(4R)-methyl 6-oxo-(2E)-hexenamide (2), corresponding to left-side of the final molecule, and E-4-2′-(1S,6-dimethylheptadiene)-(2,4′-bis-thiazole)-4-methybenzothiazole sulfone (4) corresponding to right-side.