Two New Compounds from Goniothalamus Cheliensis Hu

Goniothalamus cheliensis Hu (Annonaceace) is a small tree or shrub in Yunnan Province, southwest of China. Acetogenins, styryllactones and alkaloids1-3 from the genus were reported in the previous literature and many of them showed strong cytotoxic activities against a number of human cancer cell lines4. The titled plant has been the subject of our investigation due to the impressive cytotoxicity of its organic extract against mouse lymphocytic leukemia cells in preliminary pharmacological s…     

Proline-catalyzed stereoselective synthesis of natural and unnatural nocardiolactone

A concise diastereo and enantioselective synthesis of natural and unnatural nocardiolactone is accomplished by proline-catalyzed crossed-aldol reaction as the key step.     

三苯甲基醚直接转化成丙酮化合物的反应

介绍了一种新的高效的由三苯甲基醚直接生成丙酮化合物的方法, 也就是使三氟乙酸条件下脱三苯甲基的反应和生成丙酮化合物的反应在一个反应瓶中同时进行, 使脱三苯甲基作用后生成的醇继续反应得到高产率的丙酮化合物. 这种方法对于分子中同时含有对酸敏感的其他官能团的三苯甲基醚分子的脱保护非常有用.     

Stereoselective synthesis of the ABCD ring framework of azaspiracids

A stereoselective synthesis of the ABCD ring framework of azaspiracid-1 and azaspiracid-3 has been achieved using a tandem bis-spiroketalization protocol in the presence of a mild proton source from 1,4-diketone precursor. A tetrahydrofuran intermediate with the correct stereochemistry for the D ring of azaspiracids-1 and 3 was then taken through a linear sequence of reactions to afford the desired diketone precursor. The D-ring of azaspiracid-1 was then constructed by employing a Sharpless asymmetric dihydroxylation followed by etherification using a homoallyl derivative. The structure of the ABCD ring framework with four contiguous rings was established by extensive NMR analysis.     

GIAO/DFT evaluation of 13C NMR chemical shifts of selected acetals based on DFT optimized geometries

DFT/B3LYP calculations of the ground-state conformation of eight cyclic and acyclic acetals are presented and compared with experimental data. Results of single-point GIAO/DFT calculations at five different levels of theory show that isotropic shieldings need to be empirically scaled to achieve agreement with experimental chemical shifts. Statistical evaluation of data indicates that the most accurate prediction of 13C chemical shifts is achieved at the MPW1PW91/6-311G** level of theory. An empirical equation describing the relationship between delta values and shielding constants is postulated. This equation has been applied to the non-chair ground-state conformation of the six-membered acetonide and to the conformationally flexible benzodioxonine derivative. The agreement observed between the experimental and predicted chemical shifts shows that calculations at the MPW1PW91/6-311G** level of theory are adequate for addressing questions of conformation.     

S-甘油醛缩丙酮的合成及其Wittig反应

以L-抗坏血酸为原料合成了S-甘油醛缩丙酮;研究了S-甘油醛缩丙酮的Wittig反应立体选择性.     

具有抗HIV活性的螺环缩酮类化合物合成研究: Didemnaketals C(1)～C(8)片段 的合成

以天然薄荷酮为原料,立体选择性地合成了具有抗艾滋病活性的化合物DidemnaketalsAC(1)～C(8)片段,(3S,5R,6S)-3-甲基-5,6-丙酮化物-7-氧代-辛酸甲酯及其6R异构体。     

醋酸曲安奈德固脂纳米粒载药量及包封率的反相液相色谱法测定

建立了醋酸曲安奈德固脂纳米粒药载药量及包封率测定的反相高效液相色谱法; 采用Hypersil ODS色谱柱(250 mm×4.6 mm, 5μm), 甲醇-水-乙醚(体积比68∶32∶4)为流动相, 流速为1.0 mL·min-1, 紫外检测波长240 nm,柱温30℃,进样量为20μL,炔诺酮作内标;通过调节纳米粒表面Zeta电位使纳米粒凝聚,离心分离游离药物和纳米粒; 该方法结果准确、简便、重复性好, 可用于醋酸曲安奈德固脂纳米粒包封率及载药量的测定。     

(R)-甘油醛缩丙酮的合成及Wittig反应选择性

D-(R)-甘油醛缩丙酮是近年来研究的很多的一种用来合成一些手性药物和具有光学活性的天然产物的重要前体.用Lew is酸无水ZnC l2作为催化脱水剂,D-甘露醇与丙酮缩合反应合成二异亚丙基缩合物,然后用NaIO4氧化断键制备D-(R)-甘油醛缩丙酮,该方法具有产率高、价廉、环境友好等优点.主要研究了(R)-甘油醛缩丙酮W ittig反应的立体选择性.     

Lasiodonin Acetonide的NMR数据解析

对lasiodonin acetonide进行了¹H和¹³C NMR检测,参考lasiodonin, maoecrystal T, wikstroemioidin B和rabdocoetsin A的¹H、¹³C NMR数据,通过DEPT和¹H-¹H COSY、HSQC、HMBC等2D NMR技术对该化合物所有的¹H和¹³C NMR信号进行了全归属和详细解析.