A new fungal morphogenic substance,pyrenolide a from Pyrenophorateres

A new ten-membered lactone, pyrenolide A, was identified as a new fungal morphogenic substance and its structure including absolute stereochemistry was elucidated.     

Synthesis and metalation of trifluoromethylpyrimidines. Metalation of diazines. XVI

A new route to trifluoromethylpyrimidines is described. Lithiation of trifluoromethylpyrimidines was successfully achieved and was used to synthesize new pyrimidine derivatives. A new synthetic route to a biologically active molecule with antimycotic activities is reported.     

两款原子吸收光谱仪的塞曼背景校正装置

讨论了永久磁场塞曼背景校正原子吸收光谱仪的外光路和磁场的设计工艺,描述了可以同时获得交流磁场和直流磁场塞曼背景校正测定结果的新系统,以及可以克服洛伦兹力对测定产生影响的磁场和石墨炉的供电系统.     

Colubricidin A, a novel macrolide antibiotic from a Streptomyces sp.

A new 34-membered macrolide antibiotic, colubricidin A (1), was isolated from the fermentation broth of a new streptomyces species. Its structure was elucidated on the basis of analysis of the spectroscopic data and chemical degradation. It was identified as a glycomacrolide with an unprecedented aromatic chromophore. Colubricidin A showed excellent activity against Gram-positive bacteria.     

新型毛细管电泳化学发光系统应用于氨基酸分离测定

本研究建立一种以过氧草酸酯为化学发光体系的新型毛细管电泳化学发光系统,并将该系统应用于氨基酸的分离测定.该系统设计了新型的电极模式与反应混和模式以获得高的信号稳定性与检测灵敏度.以一端与高压电源负极相连的铂丝连接到不锈钢注射针头为接地电极,电泳毛细管穿过注射针头,且其末端到达注射针头的出口,电泳毛细宇航局末端与化学发光试剂在反应池中以相对的方向靠近.实验结果表明,该系统稳定性好、分离效率高、灵敏度高、精密度好,对天冬氨酸与亮氨酸的检出限分别为2.0和 1.1 nmol/L.峰高及迁移时间的相对标准偏差分别为2.3%～3.8%和1.2%～1.5%.     

A new lignan from the roots of <Emphasis Type="Italic">Stellera chamaejasme</Emphasis>

A new lignan, stellerachama A (1), was isolated from the roots of Stellera chamaejasme. The structure of the new compound was elucidated by analysis of spectrometric data.     

氟烷基取代的双酚A类衍生物的合成

利用相转移催化剂十六烷基三甲基溴化铵(CTMAB)催化的连二亚硫酸钠引发的苯酚衍生物与含氟碘代烷的氟烷基化反应, 合成了含氟烷基取代的酚类化合物. 研究了双酚A与含氟碘代烷的氟烷基化反应, 得到了一类重要的含氟单体, 即含氟烷基取代的双酚A衍生物. 通过改变含氟碘代烷与双酚A的摩尔比, 可以得到单取代、二取代和四取代的含氟烷基双酚A衍生物.     

Preparation and Evaluation of P-tert-Butyl-calix[8]arene-bonded Silica Stationary Phase for High Performance Liquid Chromatography

ABSTRACT

A new p-fert-butyl-calix[8]arene-bonded silica gel stationary phase was synthesized through heterogeneous functionalisation of suspended porous silica. A characterization of its structure was carried out by using elemental analysis, FTIR and ¹³C solid state NMR spectroscopy. Chromatographic performance of the new packing material was investigated by employing polycyclic aromatic hydrocarbons (PAHs) as probes and using methanol-water as mobile phase. The investigations show that the new stationary phase behaves as a reversed phase stationary phase. The liquid chromatographic separation of PAHs solutes on the new bonded phase was compared with that on a p-tert-butyl-calix[4]arene-bonded silica stationary phase. The new p-tert-butyl-calix[8]arene-bonded phase exhibited higher retention and better separation selectivity, although the carbon content and coverage of the new packing material was lower than that of the p-tert-butyl-calix[4]arene bonded silica stationary phase. A possible retention mechanism for the new packing material was also proposed.     

Drypetdimer A: a new flavone dimer from Drypetes gerrardii

A new flavone dimer, drypetdimer A (1), was isolated from Drypetes gerrardii J.Hutch The structure of the new compound was elucidated by detailed spectroscopic analysis such as 1H, 13C NMR, COSY, HMQC, HMBC and HREIMS.     

Quantum chemical modeling of chiral catalysis. Part 8. On the conformational freedom of the ketone of ketone-borane complexes of oxazaborolidines used as catalysts in the enantioselective reduction of ketones

Standard ab initio molecular orbital methods were employed to study conformational freedom of the ketone of ketone-borane complexes of chiral oxazaborolidines used as catalysts for the enantioselective reduction of ketones (CBS reduction). A formaldehyde-borane complex of 1,3,2-oxazaborolidine was used as a model system. A new conformation was found which was energetically more advantageous than the original one predicted by Corey et al. The new conformation was predicted to be destabilized by bulky substituents at the C-5 of the ring. A new class of potential oxazaborolidine catalysts for the enantioselective reduction of ketones was invented.     

金属和试剂分别过量时测定不同配合物组成的新方法

金属和试剂分别过量时测定不同配合物组成的新方法何锡文,唐志新,张贵珠,杨万龙,于贵英,史慧明（南开大学化学系,天津,３０００７１）关键词配合物组成,穷举法,光度分析本文用穷举法推导了一种新的数学模型,该法不需要假定配合比,就能测定当试剂和金属分别过量...     

A new ureido-substituted amino acid from the tubers of Gymnadenia conopsea

A new ureido-substituted amino acid, conopsamide A (1), has been isolated from an ethanolic extract of the tubers of Gymnadenia conopsea. Its structure was elucidated by extensive spectroscopic analysis, and the absolute configuration was assigned by Marfey's method. The new compound was evaluated for in vitro assay for HDAC1 (Histone Deacetylase 1) inhibitory activity.     

A New Triterpene from Cynanchum forrestii

Cynanchum forrestii Schlechter (Asclepiadaceae) is widely distributed in Yunnan, Xizang, Gansu, Sichuan, Guizhou Provinces, etc. in China and its roots have been used as an antifebrile, diuretic and analgetic in China1. In the previous investigation, we i…     

Ultrasound-promoted green synthesis of 1,4-dihydropyridines using fuctionalized MWCNTs as a highly efficient heterogeneous catalyst

A new method for multi-component synthesis of 1,4-dihydropyridine derivatives (1,4-DHPs) in the presence of meglumine supported on multiwalled carbon nanotubes (MWCNTs@meglumine) as a new heterogeneous, highly efficient and reusable catalyst was investigated. The reaction was performed under ultrasonic irradiation in EtOH at room temperature. A new, highly efficient heterogeneous catalyst, short reaction times, high to excellent yield of products, and safe and clean conditions are the advantages of the presented method.     

Determination of the Crystal Structure of a New Polymorph of Theophylline

A new approach to crystal structure determination, combining crystal structure prediction and transmission electron microscopy, was used to identify a potential new crystal phase of the pharmaceutical compound theophylline. The crystal structure was determined despite the new polymorph occurring as a minor component in a mixture with Form II of theophylline, at a concentration below the limits of detection of analytical methods routinely used for pharmaceutical characterisation. Detection and characterisation of crystallites of this new form were achieved with transmission electron microscopy, exploiting the combination of high magnification imaging and electron diffraction measurements. A plausible crystal structure was identified by indexing experimental electron‐diffraction patterns from a single crystallite of the new polymorph against a reference set of putative crystal structures of theophylline generated by global lattice energy minimisation calculations.     

Determination of the sulfur components of gasoline streams by capillary column gas chromatography with sulfur chemiluminescence detection

A method using a sulfur chemiluminescence detector (SCD) has been developed for the qualitative and quantitative determination of sulfur components in stabilized gasoline-range process streams, including blended gasolines containing between 1 and > 4000 ppm total sulfur. The detection limit per sulfur component was approximately 50 ppb. On-column injection was employed for optimum precision and accuracy. A new probe material was found which did not soften under FID operating conditions. A new method, using a hydrogen sulfide permeation tube, was developed for rapid alignment of the probe in the FID.     

A new cyanogenic glycoside from Sorbaria sorbifolia var. stellipila

A new cyanogenic glycoside, sutherlandin-5-trans-p-coumarate was isolated along with a known cardiosdiospermin-5-(4-hydroxy) benzoate fr the aerial parts of Sorbaria sorbifolia (L.) A. Br. var. stellipila MAX. (Rosaceae). The structure of the new compound was established based on spectral evidence.     

Structure of salvioccidentalin, a diterpenoid with a rearranged neo-clerodane skeleton from Salvia occidentalis

From the aerial parts of Salvia occidentalis (Labiatae) a new diterpenoid with a rearranged neo-clerodane skeleton was isolated. This new compound was named salvioccidentalin and its structure was established by spectroscopic means. A probable biogenetic relationship with salvigenolide from S. fulgens and salvileucalin A and spiroleucantholide from Salvia leucantha is proposed.     

A new insecticidal protolimonoid from Aegle marmelos

Bioassay-directed fractionation of the ethyl acetate extracts of the stem bark of Aegle marmelos Correa (Rutaceae) afforded a new compound, named skimmiarepin C, along with skimmiarepin A. The latter is a known compound but isolation from A. marmelos is new. The new compound is a senecioate ester analogue of the latter. Full identification of the new compound was achieved using spectroscopic methods on the separated mono-acetate derivatives. Skimmiarepins A and C exhibit moderate insecticidal activity against Phaedon cochleariae and Musca domestica in comparison with natural pyrethrum extract. The two epimeric acetates of skimmiarepin C are both less active.     

Novel guanidinium zwitterion and derived ionic liquids: physicochemical properties and DFT theoretical studies

A new zwitterion containing 1,1,3,3-tetramethylguanidine was synthesized using a simple method, and the physicochemical properties as well as the crystal structure of the compound were also studied. Two new acidic ionic liquids (ILs) were synthesized using the zwitterion as the precursor and the physicochemical properties including density, viscosity, thermal property, and acidic scale of the ILs were investigated. A density functional theory investigation of the geometrical structures and electronic properties of the guanidinium triflate ionic liquid was also presented for better understanding the new ILs.