Asymmetric Synthesis of Fortucine and Reassignment of Its Absolute Configuration

A convergent and enantioselective synthesis of fortucine was achieved from the starting materials tyrosine methyl ester and 3‐hydroxy‐4‐methoxybenzaldehyde. The synthesis is based on two key steps mediated by a hypervalent iodine reagent. This work has enabled us to reassign the absolute configuration of the natural product reported in the literature.     

吲哚生物碱(+)-Alsmaphorazine D的不对称全合成及其绝对构型更正

通过无痕手性转移策略实现了(+)-alsmaphorazine D的首次不对称全合成, 并对其绝对构型进行了更正. 该高效合成路径的关键步骤主要包括催化氧化环合反应、非对映选择性氧化缩醛胺化环合反应以及分子内自由基环合反应.     

Podophyllotoxin from suspension culture of Linum album

Callus and suspension cultures of Linum album as an Iranian species for synthesis of aryltetralin lactone were used. After cultivation period; we can isolate and characterize podophyllotoxin as glycosides compounds. Maximal product yield is 0.5% of the dry weight in dark grown cultures.     

1H NMR Reassignment for Z/E-Benzomalvins B and Absolute Configuration of Benzomalvin C

Chemistry of Natural Compounds - Benzomalvins B, C, and E (1, 2, and 3) were simultaneously obtained from the marine fungus Aspergillus sp. isolated from the soft coral Sinularia sp., collected...     

Synthesis of Four Diastereomers of Sclerophytin F and Structural Reassignment of Several Sclerophytin Natural Products

Synthesis of the triol that has been proposed to be the marine natural product sclerophytin F has been completed along with the syntheses of three diastereomers. Comparison of the NMR spectroscopic data for all four compounds to the data reported for the natural product reveals that sclerophytin F is not the 3S diastereomer of sclerophytin A as proposed by Friedrich and Paquette. Re‐analysis of the NMR spectroscopic data for known sclerophytin natural products and synthetic analogues leads to the conclusion that sclerophytins E and F are the same compound. This finding has allowed structural reassignment of several other cladiellin natural products.     

Reassignment of the vibrational spectrum of benzimidazole

New spectroscopic data on benzimidazole and benzimidazole-d2, using inelastic neutron scattering spectroscopy, has revealed previously unobserved bands. These new observations are incorporated into a complete assignment of the benzimidazole spectrum and shown to agree well with ab initio calculations on the system. The new assignment scheme eigenvectors have been correlated to those of indole.     

Reactions of Podophyllotoxin with DDQ

Introduction 2, 3-Dichloro-5, 6-dicyanobenzoquinone (DDQ) can react with lignans of the mono- arylidene-butyrolactone1, aryltetralin2, dibenzylbutane3 and aryltetralin-butyrolactone4,5 series. We have studied the reactions of this reagent with podophyllotoxin 1, which is a well-known natural product on account of its long history of use in folk medicine and the biological activity of its many derivatives6. In particular, derivatives of 4-demethyl epipodophyllotoxin are used in cancer chemo…     

几种制备方法的掺铁二氧化钛光催化特性

二氧化钛作为一种半导体光催化剂 ,在太阳能转换和储存 ,二氧化碳还原 ,有害复杂有机物降解等方面都引起了广泛的研究兴趣 .然而 ,二氧化钛悬浮降解体系的光催化活性却受到诸多因素的影响和制约 .有不少研究者从体系的晶体结构和表面物化性质 ,如晶相（锐钛矿 ,金红石 ,无定形）、比表面积、晶粒尺寸和表面羟基的角度讨论光催化活性 [1,2].近来有很多人希望通过掺杂方法来提高二氧化钛的光催化活性或者通过表面修饰的手法延伸光响应范围 .Kakuta、 Anderson、 Papp[3,4]等研究了复合氧化物如 TiO_2/Al2O3、 TiO_2/SiO2、 TiO_2/ZrO2、…     

Pharmacophore Reassignment for Induction of the Immunosurveillance Cytokine TRAIL

Tumor necrosis factor (TNF)‐related apoptosis‐inducing ligand (TRAIL) is an immunosurveillance cytokine that kills cancer cells but demonstrates little toxicity against normal cells. While investigating the TRAIL‐inducing imidazolinopyrimidinone TIC10, a misassignment of its active structure was uncovered. Syntheses of the two isomers, corresponding to the published and reassigned structures, are reported. The ability of each to induce TRAIL expression in macrophages was investigated and it was found that only the compound corresponding to the reassigned structure shows the originally reported activity; the compound corresponding to the published structure is inactive. Importantly, this structural reassignment has furnished a previously unknown antitumor pharmacophore.     

Synthesis of New Fluorinated Podophyllotoxin Derivatives

Five fluorinated podophyUotoxin derivatives were synthesized using dimethylamino-sulfurtrifluoride (DAST).     

Structural Reassignment of Two Polyenol Natural Products

Unusual polyenols that defied chemical principles were reassigned as the nucleosides, adenosine and uridine, using a combination of chemical intuition underpinned by Computer Assisted Structure Elucidation (CASE) and DFT methods.     

鬼臼毒素衍生物的EIMS谱分析研究

鬼臼毒素及其衍生物由于具有抗肿瘤活性而引起人们对其结构、性能及合成产生的极大兴趣[1],它们的质谱研究也曾有报道[2,3].本文报道4种衍生物的EIMS谱的分析结果,它们的结构如下:     

Synthesis and Anticancer Activity of Podophyllotoxin Derivatives

Chemistry of Natural Compounds - Two series of podophyllotoxin derivatives were synthesized by addition of a 4β-sulfanilamide to or substitution of a 4β-amide into podophyllotoxin. Their...     

自旋标记鬼桕类化合物圆二色谱的研究

给已知抗癌药物分子中引入稳定氮氧自由基,合成较母体药物高效低毒的抗癌药物已引起国内外学者的重视.我们在具有抗癌活性的鬼桕毒分子中引入稳定氮氧自由基,药理试验表明其活性保持或增加,而毒性却显著地降低.     

鬼臼毒素及其衍生物的瞬态粒子分析

分析了鬼臼毒素及其衍生物与还原性自由基(氢自由基、水合电子)作用、氧化性自由基羟基自由基和激光等作用后产生的各种瞬态粒子，对各粒子的生成和衰减过程进行跟踪，获得了各瞬态粒子的生成和衰减速率常数，进一步探讨了鬼臼毒素治疗肿瘤的构效关系。     

Reassignment of the electronic states of the trans dimer of acenaphthylene

The fluorescence and excitation spectra of trans dimer of acenaphthylene in a shpol'skii matrix at 4K are reported. The spectra at 4k are compared with the fluorescence and excitation spectra at 77K, previously reported by us. A reassignment of the origin of the two electronic states is required by such a comparison. The comparison once again establishes the point that the g state is below the u state, as was originally found from the comparison of two-photon and one-photon spectra. However, the splitting, which was originally described as “exciton splitting” should actually be ascribed to “site splitting”. The “exciton splitting”, as given in the present study, is about 130 cm⁻¹.     

Liposomes Prepared from Inverse Micelles

A method for the preparation of liposome is introduced, which contains two experimental steps: (a) inverse micelles of lecithin are formed in water-in-oil system by sonication; (b) the micelles are spread on the water surface, passed Through the oil-water interface, and transformed into liposomes in the water phase. The main advantage of this method is that the inner aqueous solution encapsulated by liposomes could be different from their enviromental medium. The liposome size is less than 0.5 μm in diameter by atomic force microscope. Comparison of activities of urease with and without liposome encapsulation suggested that urease was well entraped into liposomes.