咪唑基手性硫醚衍生物的合成与表征

硫及氮、磷、氧等原子能够与大多数过渡金属络合形成多齿的螯合物.手性的硫醚钯络合物常用于不对称碳碳键的形成、不对称的Diels-Alder、Hetero-Diels-Alder环加成、Heck反应以及羰基的加成反应中,很多手性配合物都表现出良好的手性诱导效果.     

Structure determination of selaginellins G and H from Selaginella pulvinata by NMR spectroscopy

Selaginellins G ( 1 ) and H ( 2 ), two new selaginellin derivatives, were isolated from the whole plant of Selaginella pulvinata. Their structures were elucidated, and complete assignments of the ¹H and ¹³C NMR spectroscopic data were achieved by 1D and 2D NMR experiments (HSQC, HMBC, COSY and ROESY). Compound 1 displayed good antifungal activity against Candida albicans with an IC₅₀ value of 5.3 µg/ml. Copyright © 2010 John Wiley & Sons, Ltd.     

Synthesis and thermoreversible gelation of dendron‐like polypeptide/linear poly(ε‐caprolactone)/dendron‐like polypeptide triblock copolymers

Dendron‐like poly(γ‐benzyl‐L ‐glutamate)/linear poly(ε‐caprolactone)/dendron‐like poly(γ‐benzyl‐L ‐glutamate) triblock copolymers having 2^{m + 1} PBLG branches (denoted as PBLG‐Dm‐PCL‐Dm‐PBLG, m = 0, 1, 2, and 3) were for the first time synthesized by utilizing ring‐opening polymerization (ROP) and click chemistry. The bifunctional azide‐terminated PCL (N₃‐PCL‐N₃) was click conjugated with propargyl focal point PAMAM‐typed dendrons Dm to generate Dm‐PCL‐Dm, which was then used as macroinitiator for the ROP of BLG‐NCA monomer to produce the targeted PBLG‐Dm‐PCL‐Dm‐PBLG triblock copolymers. Their molecular structures and physical properties were characterized in detail by FTIR, NMR, gel permeation chromatography, differential scanning calorimetry, and wide angle X‐ray diffraction (WAXD). The crystallinity of the central PCL segment within these copolymers is increasingly suppressed by the flanking PBLG wedges, whereas the PBLG segments gradually changed from a β‐sheet conformation to an α‐helix conformation with the increasing PBLG branches. These triblock copolymers formed thermoreversible organogels in toluene, and the dendritic topology of PBLG wedges controlled their critical gelation concentrations. The self‐assembled structure of organogels was further characterized by means of transmission electron microscopy, WAXD, and small‐angle X‐ray scattering. The fibers with flat ribbon morphology were clearly shown, and the gelation occurred through a self‐assembled nanoribbon mechanism. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 709–718, 2010     

New Sesquiterpenes from the Flowers of Chrysanthemum indicum L.

Two new guaianolides (=guaianolactones), chrysanthguaianolactone A and B ( 1 and 2 , resp.), and one new eudesmane sesquiterpene, chrysanthemdiol A ( 6 ), together with seven known sesquiterpenes were isolated from the flowers of Chrysanthemum indicum L. Their structures were elucidated on the basis of spectroscopic evidence.