The Reduction of a Natural Diterpene Containing a, B-Unsaturated Keto Group

Hedychenone (1), a diterpene containing a, B-unsaturated keto group, was reduced by aluminum-mercury alloy, and a dimerized product (2) was obtained as the major product. The coupling occurred at B position of the keto group.     

Photoisomerization of norbornadiene group in a rigid bichromophoric compound initiated by remote keto chromophore: long-distance through-bond triplet energy transfer

A diad compound 3β(bicyclo[2,2,1]hepta-2,5-diene-2-methylcarboxylate-3-carboxy)-an-drost-5-en-17-one (NBD-S-ONE) was synthesized and its photochemistry was examined. Irradiation of NBD-S-ONE in acetonitrile at λ > 300 nm selectively excited the keto chromophore. After intersystem crossing, the triplet energy of the keto group was transferred to the NBD group with 18.6% efficiency via a through-bond mechanism, resulting in the isomerization of the latter group to the quadricyclane group.     

SYNTHESIS AND NMR CHARACTERIZATION OF PRECURSORS OF EPOXY NETWORK AS POLYMER HOST FOR SOLID ELECTROLYTE

To raise the room temperature ionic conductivity and improve the mechanical strength of a PEO-based polymer electrolyte, a noncrystalline two-component epoxy electrolyte system has been prepared. The diglycidyl ether of polyethylene glycols as precursors of the system were synthesized by a two-step process. The presumed structure of the product was characterized, by ~(13)C, ~1H NMR and IR spectroscopy. It was found that a side-reaction occurred between the secondary hydroxyl group of PEG-chlorohydrin and epichlorohydrin in some degree, resulting in a by- product containing—CH_2Cl side group. By selecting a characteristic signal, which is undistorted by the increase in the length of CH_2 CH_2—O segment, a ~1H NMR approach of determining the equivalent epoxy weight (EEW) was proposed. The method is valid to specimens even though the EEW is as high as 2,000. The examination of the specimens by DSC showed that epoxidation greatly depressed the crystallinity of the PEG's, whereas the T_g was raised.     

Novel Role of Carbon Dioxide as a Selective Agent in Palladium-Catalyzed Cyclotrimerization of Alkynes

Carbon dioxide was found as a selective agent to promote the palladium-catalyzed cyclotrimerization of alkynes in water. Both aryl and alkylacetylenes afforded the corresponding cyclotrimerization products regioselectively in high yields using PdCl2, CuCl2, and CO2 as the catalytic system. However, tert-butylacetylene bearing a bulky group gave a dimerization product. Mechanism of this reaction was also discussed.     

Tetrahydrobenzo[5]helicenediol derivatives as additives for efficient proline-catalyzed asymmetric List-Lerner-Barbas aldol reactions of bulky aldehyde substrates

Proline-catalyzed asymmetric List-Lerner-Barbas aldol reactions of bulky aldehyde substrates could be efficiently carried out with dibromo-substituted helical diols P-4a/M-4a as additives. In the case of 9-anthraldehyde, the aldol product was obtained in 83% yield and 99% ee. An edge-to-face π-π stacking between the anthracenyl group in TS(R) and the phenyl group of the additive might contribute to the increase of enantioselectivity.     

SYNTHESIS OF POLYURETHANE MODIFIED BISMALEIMIDE (UBMI) AND POLYURETHANE-IMIDE ELASTOMER

Urethane modified bismaleimide(UBMI)was synthesized by the reaction of maleic anhydride(MA)with NCO group terminated polyurethane prepolymer(PUP)in presence of acetone.The product was determined by infrared analysis. Then ultrasonic assistant process was introduced into the solvent removal of the prepolymer mixture of UBMI and PUP. Polyurethane-imide(PUI)elastomer was synthesized from the above PUP-UBMI prepolymer mixture by the infusion technology with 2,5-dimethyl-2,5-bis(tert-butylperoxy)-hexane(B25)a...     

Synthesis,Crystal Structure and Fluorescence of a Bicyclic Product Containing Chromene and Propargylamine Skeleton

The bicyclic product containing a chromene skeleton and a propargylamine skeleton(C_(22)H_(22)N_2O_2) was synthesized from the double sites of terminal alkyne, piperazine derivative and formaldehyde via one-pot procedure. Its structure was characterized by ~1H NMR, ~(13)C NMR, IR and H RMS, and further confirmed by single-crystal X-ray diffraction. It crystallizes in the monoclinic system, space group P21/n with a = 12.6571(14), b = 11.3249(12), c = 12.6571(14) ?, β = 105.22°,V = 1750.6(3) ?~3, Z = 4, R = 0.0568 and w R = 0.1444. The fluorescence of the product was discussed.     

Preparation of polymeric microspheres with high content of sulphonate groups

<正>Poly(styrene-co-sodium styrene sulphonate)(P(St-NaSS)) latex particles were prepared using the mixture of ethanol and water as continuous phase in the presence of surfactant by dispersion--emulsion combined polymerization.The influence of recipes on polymerization process as well as the content of sulphonate group in the purified products was investigated.Results showed that the copolymerization could be performed smoothly.When the mole ratio of NaSS/St/divinyl benzene(DVB) was 25/75/2 and the weight ratio of ethanol/water was 2/11,the product showed a low weight loss in methanol extraction purification,and the NaSS unit ratio in the purified product reached 20.6 mol%,which was close to its theoretical value of 24.9 mol%.     

一种含硝基的Plakoric酸类似物的合成

Synthesis of a nitro analogue of plakoric acid is presented. The peroxy bond was incorporated into the substrate structure through a boron trifluoride etherate catalyzed methoxy-hydroperoxy group partial exchange reaction in diethyl ether with urea-hydrogen peroxide complex （UHP, a commercially available solid reagent） as the source of the hydrogen peroxide. Under the given conditions, only one of the two methoxyl groups underwent the MeO—— OOH exchange and the resulting hydroperoxy hemiketal proceeded directly to the end product through an intramolecular Michael addition of the hydroperoxyl group to the nitro group activated carbon-carbon double bond.     

Transalkylation of N-methyl tertiary amines with 3, 4-dibromobutenolides

The selective transalkylation of N-methyl tertiary amines with 3,4-dibromobutenolides is described.The N-methyl group of the parent tertiary amines was replaced by alkenyl units of the butenolides;and a series of butenolide-containing tertiary enamines were obtained in moderate to good yields.Interestingly,the product 2b has shown a promising anticancer activity against HeLa cell lines(IC50=0.19 mmol/L).     

A FACILE SYNTHESIS OF 1.2-BISPYRROLEETHYLENS

1. 2-Bispyrroleethylenes can be easily syntnesized bv cc,-,pt}ngpyrrolealdehyde using TiCl_4/Zn as a catalyst. It was found that when theR group is COMe or CO_2 Et, the product is a mixture of trans and cisisomers, and in the other cases, the products are pure trans isomers.     

Synthesis, Characterization, Crystal Structure and Antibacterial Activities of a Nickel(Ⅱ) Complex with 2'-(2-Thienylidene)-hydroxybenzoylhydrazide

In the ethanol solvent, a nickel(II) complex Ni(C12H10N2O2S)2 upon reaction of 2'-(2-thienylidene)-hydroxybenzoylhydrazide with nickel acetate was synthesized, and its structure was characterized by IR, UV, elemental analysis and X-ray diffraction analysis. The crystal belongs to monoclinic system, space group C2/c with a = 22.052(3), b = 5.9681(6), c = 18.522(2) , β = 110.679(4)°, V = 2280.6(4) 3, Z = 4, Mr = 551.27, μ = 1.606 mm-1, Dc = 1.075 g/cm3, F(000) = 1136 and Rint = 0.0556. The nickel(Ⅱ ) atom in the compound is four-coordinated with two nitrogen atoms from amide and two oxygen atoms from keto group. The biological activities have been measured, show- ing the compound exhibits better anti-bacterial activity than the ligand.     

Synthesis of azo derivatives of 4-aminosalicylic acid

For searching a better 4-aminosalicylic acid derivative with higher activity and less side effects against the inflammatory bowel disease, 4-aminosalicylic acid (4-ASA) was protected by benzyloxycarbonyl and acetyl, respectively. The resultant was hydrogenized to remove protective group of amino group, then the product was reacted with NaNO2 to give diazonium salt, which was conjugated with salicylic acid, hydroxybenzene, TV-salicyloyl glycine acid to get azo derivatives of 4-ASA. The azo derivatives were hydrolyzed under the alkaline condition to get the target products. All compounds were characterized by FT-IR, 1H NMR, 13C NMR spectra in details. New derivatives of 4-ASA were characterized. The synthetic route was reasonable and feasible.     

THE CRYSTALLOGRAPHIC STRUCTURE OF THE PHOTOOXIDIZED PRODUCT OF HYPOCRELLIN A AND THE STUDY OF THE PHOTODYNAMIC ACTION MECHANISM

In attempting to study the phototherapeutic action and the photosensitized oxygenation mechanism, we have determined the crystal structure of the main oxidized product of hypocrellin A (HA). It was crystallized in monoclinic system with space group P2_1. The cell data are: a=10.030(3), b=8.877(3), c=15.764(5), β=104.50(2)°, Z=2. The crystal structure has been determined by direct method and refined to a final R of 0.055 based on the 1408 observed reflections with l>2.5σ(Ⅰ). The photooxidized product is composed of a heptacyclic aliphatic hydrocarbon connecting with two α-naphthoquinone derivatives as its skeletal molecule. No peroxidic linkage has been found. On the basis of the crystal structure determined, we have deduced part of the process of formation of the oxide, ⅰ. e. firstly, the peroxide was formed by photocycloaddition of oxygen molecule to Hypocrellin A, then thermodissociation took place to form a stable oxide.     

A practical synthesis of novel hydroxyl-substituted macrocyclic tri-,tetra- and hexa-amines

Macrocyclic tri- and tetra-amines containing a hydroxyl group in the ring have been prepared in moderate yields by a 1:1 cyclocondensation of l,3-dichloro-2-propanol with the disodium salt of N-tosylated diethylenetriamine and triethylenetetraamine.In the case of condensation of 1,3-dichloro-2-propanol with the disodium salt of N-tosylated diethylenetriamine,the 2:2 cyclocondensation product,dihydroxyl macrocyclic hexaamine,was also isolated.     

Ring-closure Reaction to Novel Quinoline Derivatives and Their Structural Characterization

In the condensation of arylaldehydes with arylethylidenemalononitriles, it was found that, besides the normal product dienes a, the ring-closure product quinoline derivatives b can be also obtained in 26%--50% yields. The substituent effects were also examined and a possible reaction mechanism was proposed for the formation of b. The X-ray crystal structure of lb confirms the structure of the ring-closure product.     

Fabrication of Dendrimer－like PAMAM Based on Silica Nanoparticles

A G 4.0 dendrimer-like poly (amido amine) (PAMAM) based on silica nanoparticles was fabricated via a divergent approach.It was built from γ-aminopropyi silica nanoparfides (APSN) core via repetitive addition of acrylate (MA) and hexylenediamine (HDA). FT-IR and EA were used to monitor the progress of dendrimer during each step. The amino group content of the resulting product increased from 0.49 to 3.72 mmol/g after the 4th generation. In addition, the percentage of grafting increased with increasing generation and reached to 65.9% after 4th generation. It was found that the resulting silica nanoparticles could be dispersed in methanol with a mean hydrodynamic particle diameter of 152.7 nm although the silica nanoparticles had agglomerated during the storage period.     

由乙氧基铅配合物制备纳米PbO

Lead complex was directly synthesized by electrochemical dissolution of lead in a cell without separating the cathode and anode. The product was characterized by FTIR, Raman spectra and ¹H NMR. The xerogel was prepared by a direct sol-gel of the electrolyte solution and then dryness of it. The xerogel was heated at 450 ℃ for 2 h to obtain the nano-PbO powder. FTIR, XRD, and TEM were used to investigate the structure of nano-PbO. The results show that the lead complex is Pb(OEt)₂(acac)₂, which contains acac- group and could prevent the precursor from hydrolysis and sintering during the calcinations process. The nano-PbO of 20～30 nm was thus obtained in a high purity by drying at 450 ℃.     

Synthesis, Characterization, Crystal Structure and Antibacterial Activities of a Nickel（Ⅱ） Complex with 2＇-（2-Thienylidene）-hydroxybenzoylhydrazide

In the ethanol solvent, a nickel(Ⅱ) complex Ni(C12H10N2O2S)2 upon reaction of 2'-(2-thienylidene)-hydroxybenzoylhydrazide with nickel acetate was synthesized, and its structure was characterized by IR, UV, elemental analysis and X-ray diffraction analysis. The crystal belongs to monoclinic system, space group C2/c with a = 22.052(3), b = 5.9681(6), c = 18.522(2) (A), β = 110.679(4)° , V = 2280.6(4) (A)3, Z = 4, Mr = 551.27, μ = 1.606 mm-1, Dc = 1.075 g/cm3, F(000) = 1136 and Rint = 0.0556. The nickel(Ⅱ) atom in the compound is four-coordinated with two nitrogen atoms from amide and two oxygen atoms from keto group. The biological activities have been measured, show- ing the compound exhibits better anti-bacterial activity than the ligand.     

Reactions of Thienyl Containing Trisilane Under Irradiation

2-phenyl-2-furylhexamethyltrisilane and 2-phenyl-2-thienylhexamethyltrisilane (1) weresynthesized via Grignard-like reactions. The photolysis of 2-phenyl-2-furylhexamethyltrisilane inthe presence of 2,3-dimethyl-1,3-butadiene led to normal silylene-olefin addition and silylene C-Hinsertion reactions. Whereas, when 1 was photolyzed in the methanol-cyclohexene system, a radicalreaction mechanism is occurred. We suspect that the sulfur atom of the thienyl group strongly stabi-lized the silyl radical. This result was supported by both identifyling its typical radical reactions prod-ucts and ESR spectra of its quenching product with radical quencher.