Proceedings [of] 10th Asian chemical congress: Sessions. 4. Organic chemistry. Hanoi, 2003

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Biomimetical synthesis of +- vincadifformine and +- -vincadifformine: Starting from compound 10, the syntheses of +- vincadifformine (8) and +- -vincadifformine (9) have been achieved by using Polonovski reaction of 18 and intramolecular cyclization of secodines 3.4 as the key steps.
Site selective degradation of myoglobin by polymeric artificial metalloproteases: Mononuclear, dinuclear, and tetranuclear artificial metalloproteases were prepared by attaching respective catalytic modules containing the Cu(II) complex of cyclen (Cu(II)Cyc) to a derivative of crosslinked polystyrene. The polymeric artificial metalloproteases effectively cleaved peptide bonds of myoglobin (Mb) by hydrolysis. The proteolytic activity increased considerably as the catalytic group density was raised: the ratio of kcat/Km was 1:13:100 for the mono-, di-, and tetranuclear catalysts. In the degradation of Mb by the dinuclear catalyst, two pairs of intermediate proteins accumulated. One of the two initial cleavage sites leading to the formation of the protein fragments is identified as Gln(91)-Ser(92) and the other is proposed as Ala(94)-Thr(95). Based on a molecular modeling study by using the X-ray crystallographic structure of Mb, the site-selectivity is attributed to anchorage of one Cu(II)Cyc unit of the catalytic module to a heme carboxylate of Mb. The high site selectivity for the initial cleavage of a protein substrate and mechanistic analysis of the catalytic action are unprecedented for polymeric artificial enzymes.
Studies on the mass spectra of formazane derivatives containing heterocycles: The mass spectra of arylfomazanes and arylsulfonylfomazanes series have been investigated and shown that arylformazanes exit in equivalent tautomeric balance and arylsulfonylformazanes exit in arylazosulfonylformazanes. The typical peaks in the mass spectra are formed obviously by cleavage of the bonds: -C=N-/-NH, -C-/-N=N-/-C-, - C=N-/-NH-/-SO2- and -C-/-N=N-/- SO2-. The structure of these formazanes has been effectively determined base on the fragmentary mechanism.
Synthesis and investigation of the corrosion inhibition properties on some azomethines of substituted indolyldene-5-amino-2-methylindoles and indolylidene-5-amino-1-methyl-2-methylindoles: Some azomethine of 5-amino-2-methylindole and 5-amino-l-ethyl-2-methylindole series with different substituted indole-3-aldehydes have been synthesized (I-VII) [1] and some results of their corrosion inhibition evaluation on mild steel (CT-3) in O.5M HCl soluion have been obtained by using the electrochemical polarization method. The productivities were 40-84%. The obtained products were the solid substances with high melting points, dissolved in some common organic solvents (ethanol, methanol, benzene, toluene, DMF, ethyl acetate). The corrosion inhibition properties have been specified by immersion method with Z=50-92% (for Al) and Z=50-95% (for steel CT-3) and by measuring by resistance polarization method Rp, the corrosion density current icorr (A/cm2), the potential Ecorr (m V/SCE) and the corrosion productivity Hj (%) have been determined: H=50-74% (for Al); H=67-87% (jor steel CT-3); H=36-83% (for Cu) [2. 4-6]. Structure, relative energies of the salient stationary points, including stable minima, associated with rotation about the N10-C6 bond of the amine ring hare been determined at the AM1 method [3].
Synthesis and study of N-substituted hydrazides of 4.4-ethylenedioxypentanoic acid: Twenty-eight N-substituted hydrazides of 4.4-ethylenedioxypentanoic acid have been obtained starting from levulinic acid, aromatic and heterocyclic aldehydes or ketones. The structures of these new compounds have been confirmed by using UV, JR, 1H-NMR, 13C-NMR and mass spectra. The spectral properties and the biological activity have been investigated. Some tested compounds exhibit bactericidal and fungicidal activity.
Synthesis and study on electronic spectra of some azomethines containing1,3.4-oxadiazole and 1,3,4-thiadiazole rings: Some azomethines containing 1,3,4-oxadiazole and 1,3.4-thiadiazole rings have been semisynthesized from eugenol. Their electronic spectra has been studied. The relation between their structures and the electronic spectra has been explained. A linear relationship between v and a Hammet constant of the substituents in azomethines has been found.
Synthesis of MCM-22 zeolite containing of iron and theircatalytic properties in the oxidation of benzylic alcohol: Three Fe MCM-22 zeolites have been synthesized and theirstructure have been studied by using X-ray, IR and Raman spectra methods. These zeolites were used as catalysts in the selective oxidation reaction of benzylic alcohol. The product of this oxidation reaction was benzaldehyde.
Synthesis of bicyclo[4.3.0] nonane ring system by a new cyclization of pentadienal: Bicyclo[ 4.3.0 }nonane carbon framework was synthesized utilizing a new type of iron-induced cyclization reaction of 2-{trimethylsilylmethyl)pentadienal. Namely, cyclization of (E)-3-{cyclohex-1-en-1-yl)-2-{trimethylsilylmethyl)prop-2-en-1-al underwent by treatment with FeCl3 in CH2Cl2 to afford 8-methylenebicyclo[4.3.0]non-9-en-7-ol and its trimethylsilyl ether. The corresponding (Z}-isomer gave several cyclization products as a complex misture. Substituent effect on cyclohexane ring was also studied using {E}-3-(4-alkylcyclohex-1-en-1-yl}-2-{trimethylsilylmethyl)prop-2-en-1-al (alkyl=Me and t-Bu) affording two isomer of the products in 1:1 ratio. The stereochemistry is discussed.
Synthesis of corrosion inhibitors based on modifying succinimides with diisocyanates: Every engine oil needs a corrosion inhibitor. Protecting engines, equipments and machines from corrosion is always a big challenge for lubricant manufacturers. It is the purpose of this article to introduce an extremely effective corrosion inhibitor can be used for many kinds of lubricants, its preparing and testing in the laboratory.
Synthesis, structure and properties of some 1,2,5-oxadiazole derivatives from anethole: 3-Methyl-4-(4'-methoxyphenyl) furoxane has been prepared starting from anethole. Its substituted derivatives as bromo-, nitro-, amino-, amide compound have been obtained. Some azo-and azomethine compounds have been synthesized. The structure of reported compounds have been confirmed by MS, UV-Vis, IR, and NMR spectroscopy. The test for antimicrobial activities shown that the minimum inhibition concentration of the amino-, azo- and azomethine compounds on P. aeruginosa and B. subtillis is of 12,5-50 mg/ml.
The quantium calculating application in fries rearrangement of resorcinol diacetate: The Fries rearrangement of resorcinol diacetate gives more than one product. The result of this reaction[1] was showed when 1 mole of resorcinol acetate reacted with 3 moles of aluminum chlorides: Reaction at 140-145oC: resacetophenone (28%), and 2.4-diacetylresorcinol (48%). Reaction at 180-185oC: resacetophenone (37%), and 2.4-diacetylresorcinol (60%). Reaction at 205-210oC: resacetophenone (7%), and 2.4-diacetylresorcinol (48%), and 4.6 diacetylresorcinol (14%). However, both the preferable formation of 2.4-diacetylresorcinol and the formations of the other rearranged products have not been clearly explained. Besides re-examining those results by doing experiments, we have used AM1 quantum method[2] for calculating the intermediate products of Fries rearrangement of resorcinol diacetate to explain the trend of this reaction. The calculated results have not only provided a simple way to explain the formation of rearranged products but also enhanced us to improve experimental conditions in order to obtain expected products.
Thiocarbamolyation of amine-containing compounds by tetramethylthiuram disulphide: XV. Synthesis and transformation of N'-1-[3-hydroxy-4-(5-mercapto-1,3,4-oadiazol-2-yl)-phenyl]-N,N-dimethylthiourea: Thiocarbamoylation of 4-aminosalicylic hydrazide by tetramethylthiuram disulphide in Dioxane or DMF afforded N'-[3-hydroxy-4-(5-mercapto-l,3,4-oxadiazol-2-yl)phenyl]-N,N-dimethyl thiourea with the yield of 70%. The later was converted into 5-isothioxianato-2-(5-mercapto-l,3,4-oxadiazol-2-yl)phenol with the yield of 90%, under action of the mineral acids (HCl, H2SO4). The reaction conditions and the structure of the obtained products were discussed.
Versatile preparation of poly (1.4-phenylenevinylene-co-1.4-phenylene-1.2-ethanediyl) by CVD polymerization of p-(methoxymethyl) benzyl chloride: It was demonstrated that a series of copolymers consisting of l.4-phenylenerinylene (PV) and 1.4-phenylene-l.2-ethanediyl (PE) units could be prepared from a single monomer, p-(methoxymethyl)benzyl chloride, via the chemical vapor deposition polymerization (CVDP) method. The composition of the copolymers could be varied simply by altering the monomer activation temperature. The higher the temperature, the lower the content of the PV unit became. The photo (PL)-and electroluminescence (EL) properties of the copolymers, that revealed a blue-shift when compared with PPV, strongly depend on the amount of the PE units incorporated. The external quantum efficiencies of the electroluminescence devices having the configuration of ITO/PEDOTPSS/copolymer/Al-Li were higher than that of PPV, which can be ascribed to the improved confinement of excitons.
[4+2] cycloaddition reaction of monosubstituted arenediazenium ions cyclic dienes. Formation of 1,2,3,6-tetrahydropyridazines: As expected, cyclohexadiene reacts readily and smoothly with arenediazenium ions 2 by way of a concerted [4+2]cycloaddition reaction, and the corresponding bicyclic cycloadducts 2-aryl-2,3- diaza-bicyclo[2.2.2]oct-5-ene 3 are formed in rather high yields. In contrast, the cycloadducts 5 and 6 obtained from the cyclization of arenediazenium ions with furan under the same reaction conditions differed from expectation.