1998 Volume 9 Issue 4

Studies on Diastereoselective Intramolecular meta-Cycloaddition of Arene to Olefin (Part Ⅱ)
Xiu Min SHEN , Liang Dong SUN , Cong ZHANG
1998, 9(4): 321-323
[Abstract](211) [FullText HTML] [PDF 143KB](0)
The photoinduced intramolecular meta-cycloaddition of bichromophores 1a-1d gave diastereoselectively two types of adducts 2a-2d and 3a-3d respectively. The observed stereochemistry of cycloaddition is rationalized in terms of hydrogen bond effect induced by the 4-hydroxy group in the 5-phenylpent-1-ene skeleton.
Studies on the Diastereoselective Alkylation Reaction Employing Isomannide and Isosorbide as Chiral Auxiliaries
Jian Qiang WANG , Ming Hua XU , Min ZHONG , Guo Qiang LIN
1998, 9(4): 325-328
[Abstract](220) [FullText HTML] [PDF 161KB](1)
The studies on the asymmetric alkylation of ester employing D-Isomannide and D-isosorbide as chiral auxiliaries were described. The diastereomeric excess of this reaction was up to 90%.
One-Pot Synthesis of Substituted Cyclohexanes from Condensation of Aldehyde and Methylketone
Ye Gao YIN , Kung Kai CHEUNG , Wing Tak WONG
1998, 9(4): 329-332
[Abstract](221) [FullText HTML] [PDF 118KB](3)
Three asymmetrically substituted cyclohexanes were prepared from one-pot reactions of aldehydes and methylketones, and the products were characterized by single crystal structure analysis, NMR spectroscopy and microanalysis.
The Cleavage Effect of Histidyl-Lysine on RNA
Xiang Hong LI , Rong WAN , Qiong ZHANG , Yu Fen ZHAO
1998, 9(4): 333-334
[Abstract](224) [FullText HTML] [PDF 98KB](0)
The cleavage activity of histidyl-lysine dipeptide (His-Lys) on RNA was studied and compared with that of histidine. With the addition of the lysine residue, the cleavage activity was increased about 10-fold compared to that of histidine. The cleavage mechanism of His-Lys was also discussed.
Enantioselective Hydrolysis of α-Amino Acid Ester by Chiral Metallomicelles
Jing Song YOU , Xiao Qi YU , Xiao Ling ZHANG , Ru Gang XIE
1998, 9(4): 335-337
[Abstract](215) [FullText HTML] [PDF 141KB](0)
A series of chiral lipophilic Cu(Ⅱ) complexes were investigated as catalysts for the enantioselective hydrolysis of R(S)-p-nitrophenyl N-dodecanoyl-phenylalaninate in micelles. The highest enantioselectivity (kR/kS=7.81) was observed in a mixed micellar system composed of 1-Cu(Ⅱ) and Brij35.
A Rapid and Convenient Procedure for the Permethylation of Polysaccharides
Cheng Gang HUANG , Chen LI , Zhi Xiao LI , Yao Zu CHEN
1998, 9(4): 339-340
[Abstract](213) [FullText HTML] [PDF 98KB](0)
Butyllithium was directly added to the solution of polysaccharides in dimethyl sulfoxide. The methylsulfinyl carbanion, as a sugar alkoxide forming reagent, was generated from the solution. All the operations were performed as one-pot reactions. Five polysaccharides from different traditional Chinese medicines and three dextrans were methylated and satisfactory results have been achieved.
The Synthesis and Optical Absorption of Bisazo Pigments from 1,5-Diaminoanthraquinone
Yu Hong ZHANG , Qing Sen YU
1998, 9(4): 341-343
[Abstract](200) [FullText HTML] [PDF 101KB](0)
Ten new bisazo pigments were synthesized by coupling 1,5-diaminoanthraquinone with various couplers. The absorption studies show that a red shift of 50 nm is obtained when the coupler component is changed.
The Activation and Carbonylation of the C-Cl Bond Catalyzed by Transition-Metal Complexes
Wei Zhong ZHENG , Wen WAN , Fu Jiang DING , Liang Fu ZHANG
1998, 9(4): 345-346
[Abstract](188) [FullText HTML] [PDF 84KB](1)
Diethyl malonate was synthesized by transition-metal catalyzed alkoxycarbonylation of ethyl chloroacetate. The results show that the conversion of ethyl chloroacetate is greater than 92%, and the selectivity to diethyl malonate is 67.5%.
Total Synthesis of Several 3, 3"-Biflavones
Lian Yun ZHAO , Xian Yong BU , Yu Lin LI , Wen CEN , Ya Cheng XING
1998, 9(4): 347-349
[Abstract](183) [FullText HTML] [PDF 96KB](0)
Three 3,3"-biflavones were synthesized by using iodination of flavones through I2-CAN system as the key step followed by the coupling of 3-iodoflavones under the Ullmann reaction conditions.
Total Synthesis of Several 8, 8",-Biflavones
Lian Yun ZHAO , Shi Jun DA , Yu Lin LI , Wen CEN , Ya Cheng XING
1998, 9(4): 351-352
[Abstract](177) [FullText HTML] [PDF 67KB](0)
Four 8,8"-biflavones were synthesized by the iodination of 2'-hydroxychalcones at 8- position in I2-H2SO4-DMS0 system as the key step followed by coupling under Ullmann reaction conditions.
Total Synthesis of (±)Hinesol
Ping XIE , Shu Feng CHEN , Xiao Tian LIANG
1998, 9(4): 353-356
[Abstract](194) [FullText HTML] [PDF 160KB](0)
Stereoselective total synthesis of (±)hinesol 1 was achieved from readily available starting materials and thorough mild reaction conditions. The structure of synthetic hinesol was confirmed by chemical transformation.
Total Synthesis of (±)Chrysotricine
Guang Xing WANG , Shu Feng CHEN , Xiao Tian LIANG
1998, 9(4): 357-360
[Abstract](178) [FullText HTML] [PDF 170KB](0)
(±)Chrysotricine 1 was synthesized by a facile route. The key steps in the synthesis were aldol condensation of dilithium salt of harman 4 with 6-methyl-5-hepten-2-one 5 and cyclization of compound 6 using MCPBA. The 1HNMR spectrum of synthetic product was identical to that of the natural sample.
Concise and Effective Synthesis of Yakuchinone-A
Chu Sheng HUANG , Xi Hui CHEN , Yu Lin LI , Hong Xing LIU , Ying LI
1998, 9(4): 361-363
[Abstract](191) [FullText HTML] [PDF 82KB](2)
Yakuchinone-A, a natural strong pungent flavor isolated from Alpina oxyphylla, was synthesized starting from vanillin and cinnamaldehyde in five steps and in 62% overall yield.
Stereoselective Synthesis of 3(R) and 3(S)-Hydroxyeicos-4(E)-en-1-yne, a Component of the Marine Sponge Cribrochalina Vasculum
Wei LU , Guang Rong ZHENG , Da Xin GAO , Jun Chao CAI
1998, 9(4): 365-367
[Abstract](186) [FullText HTML] [PDF 88KB](0)
Stereocontrolled synthesis of 3(R) and 3(S)-hydroxyeicos-4(E)-en-1-yne has been achieved through double elimination of chloride intermediates 8 and 11,which were prepared from acetylenic alcohol intermediates 1 and 10.
Synthesis and Anticonvulsant Activity of γ-Aminobutyric Acid Derivatives
Mu YUAN , Yu Guo ZHONG , Qi Jie PANG
1998, 9(4): 369-371
[Abstract](182) [FullText HTML] [PDF 84KB](0)
Under physiological conditions, γ-aminobutyric acid poorly crosses the blood-brain barrier. It is likely that a non-toxic derivative of γ-aminobutyric acid which enters the brain easily will have useful anticonvulsant activity. 16 derivatives of γ-aminobutyric acid with an imine link to a lipophilic carrier were prepared and tested for anticonvulsant activity; six compounds show anticonvulsant activity.
Attempted Removal of Oxygen Function at 1-Position of 10-Deacetylbaccatin Ⅲ
Da Li YIN , Yoshinori SEKIGUCHI , Kazuya KAMEO
1998, 9(4): 373-375
[Abstract](187) [FullText HTML] [PDF 102KB](0)
1-Hydroxyl acetylation of 10-deacetylbaccatin III was achieved by removing the neighboring bulky 2-benzoyl group and oxidizing 2-hydroxyl group to a ketone function, but attempted reductive cleavage of 1-acetoxy gave rearranged products under different conditions with or without proton source.
Mapping the Antigenic Peptides of Sm26/2 in Glutathione STransferases of Schistosoma Mansoni
Jia Xi XU , Meng Shen CAI
1998, 9(4): 377-379
[Abstract](192) [FullText HTML] [PDF 125KB](0)
Six antigenic peptides of Sm26/2 glutathione S-transferase of schistosoma mansoni have been predicted according to their hydrophilicity, flexibility, accessibility, charge distribution and β-turn in the secondary structure by the determination of its primary structure, and synthesized by solid phase method. Two of them showed good antigenicity by Dot-ELISA. They would be candidate peptides of synthetic anti-schistosomal vaccine.
Detection of Claisen Rearrangement Occurring in Allyl Phenyl Ether by in situ GC/MS
Jian Jun ZHAI , Wei YING , Fan Zhi ZHA , Yao Zu CHEN
1998, 9(4): 381-384
[Abstract](190) [FullText HTML] [PDF 137KB](0)
We report here a new strategy for revealing the Claisen rearrangement of allyl phenyl ether occurring in the gas phase by in situ GC/MS technique. The Ciaisen rearrangement has been observed when allyl phenyl ether passed through the capillary column at certain temperatures. The relative proportion of rearrangement products is dependent on the temperature of the capillary column and the substituents on the phenyl ring.
Correlation Analysis of the Fluorescence Data of Some Benzaldehyde Derivatives by the Dual-Parameter Equation
William Fa Xiang DING , Xi Kui JIANG
1998, 9(4): 385-387
[Abstract](181) [FullText HTML] [PDF 99KB](0)
The fluorescence emission wavelength [λmax(em)] values of three types of benzaldehyde derivatives, namely, ethylene acetals (1-Ys), 4-nitrophenylhydrazones (2-Ys) and phenylhydrazones (3-Ys), have been measured. Correlation analyses by the dual-parameter equation show that the λmax(em) values of 1-Ys are mainly affected by the spin-delocalization effects of the substituents, while those of 2-Ys are mainly affected by the polar effects. However, those of 3-Ys are independent of the substituents.
What Is the Structure of Pterodonoic Acid?
Yu Xin CUI , Zhao Ming XIONG , Gang ZHOU , Yu Lin LI
1998, 9(4): 389-391
[Abstract](185) [FullText HTML] [PDF 117KB](1)
In this paper, it is shown that pterodonoic acid may or may not have the structure of 3-oxoeudesma-4, 11-dien-12-oic acid 1 by comparison of their spectral data. But it is certainly not 10-epi-3-oxoeudesma-4, 11-dien-12-oic acid 2, which is synthesized from dihydrocarvone 3.
Metabolites of Icariin in Urine Following Oral Administration
Feng QIU , Ying Jie CHEN , Yoshihiro KANO , Xin Sheng YAO
1998, 9(4): 393-395
[Abstract](195) [FullText HTML] [PDF 120KB](0)
Urinary metabolites of icariin, present in Epimedium, were investigated using rats. In the urine of rats administered icariin orally, two major metabolites were detected, which were identified as icariside II and icaritin by means of spectral data.
Selective Dealumination of ZSM-5 by Hydrothermal Treatment
Kui ZHANG , Huai Bin ZHANG , Shou He XIANG , Shang Yuan LIU , He Xuan LI , Fei HE
1998, 9(4): 397-400
[Abstract](194) [FullText HTML] [PDF 188KB](0)
We studied the factors affecting the framework aluminium distribution in the ZSM-5 structure by hydrothermal treatment under different conditions. 27A1MASNMR, XPS and chemical analysis revealed that with steaming at lower water vapor pressure, the framework aluminium located at the external surface is less stable. Steaming at higher water vapor pressure is beneficial in removing the framework A1 in HZSM-5, and especially helpful in removing that located at the internal surface of HZSM-5. By changing steaming conditions, one may control the framework aluminium distribution in the HZSM-5 structure.
Luminescence of Eu2+ in Strontium Aluminum Oxide System with Long Decay Property
Yong QIU , Hai Tao SUN
1998, 9(4): 401-402
[Abstract](189) [FullText HTML] [PDF 79KB](0)
A long decay luminescent powder based upon the strontium aluminum oxide system with Eu2+ as the activator was produced. It was found that the variation of the molar ratio of A1 to Sr leads to a change in emission color. The two emission centers responsible for the color change have been identified.
Hydroxyapatite/Metal Composite Coatings Prepared by Two-step Electrodeposition Method
Jian Min ZHANG , Chang Jian LIN , Zu De FENG , Zhao Wu TIAN
1998, 9(4): 403-406
[Abstract](177) [FullText HTML] [PDF 178KB](0)
A two-step electrodeposition method was developed to prepare hydroxyapatite/metal composite coatings. Hydroxyapatite coatings were fabricated by electrochemical deposition and post-treatment with alkaline solution, and then cobalt was electrodeposited to form hydroxyapatite/cobalt composite coatings to improve its mechanical properties of bonding strength.
Morphological and Structural Studies of sPS/aPS Blends
Sheng Qing XU , Bin CHEN , Yang LIU , He Sheng CHEN , Bao Tong HUANG
1998, 9(4): 407-410
[Abstract](191) [FullText HTML] [PDF 169KB](2)
The morphology and structure of the syndiotactic polystyrene (sPS)/atactic polystyrene(aPS) blends with various compositions have been studied by means of DSC, optical microscopy, SAXS,and WAXD. The results show that aPS is miscible with amorphous region of sPS. There is no macroscopic evidence that aPS forms separated domains in the blends. The decrease in crystallinity of sPS in the blends implies segregation of the aPS to the interflbrillar regions of the spherulites of sPS. The constancy of interlamellar distance and melting points indicates that the fibrillar structural units of sPS is unchanged on addition of aPS to sPS, and the unchanging parameters of the sPS unit cells mean that aPS does not enter the unit cells of sPS.
Theoretical Study on the Molecular Orbital and Stabilization Energy of Substituted Lithium Carbene Cations
Ji Hai LI , Sheng Yu FENG , Jian Jun GAO
1998, 9(4): 411-414
[Abstract](170) [FullText HTML] [PDF 170KB](0)
The stabilization energies of substituted lithium carbene cations were calculated by using ab initio molecular orbital theory, and the relationship between the stabilization energies and molecular orbitals was discussed. The substituents with n donor engender strong stabilization to CH2Li+. The calculations show the Y-C* bond lengths of cations become shorter and H-Y bond lengths longer than those of corresponding neutral molecules.
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