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1.
The first total synthesis of (+)?3-deoxyaphidicolin, a selective inhibitor of eukaryotic DNA polymerase α, has been completed efficiently and stereoselectively starting from 1-abietic acid. 相似文献
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3.
Nucleophile(s) almost exclusively added from the equatorial side of 2-nitro-β--2-enopyranoside and the axial side of 2-nitro---1-enitol. On the other hand, methoxide and -butyl peroxide ions approached from the equatorial side of 2-nitro-α--2-enopyranoside, whereas methanol and hydrogen peroxide ion from the axial side. 相似文献
4.
Aryl(chloromethyl)thallium chlorides, Ar(ClCH2)TlCl (Ar=C6H5, p-CH3C6H4) have been prepared by treatment of arylthallium dichlorides with diazomethane. The derived carboxylates, Ar(ClCH2)TlX, react with HgX2 to give the dicarboxylates, (ClCH2)TlX2 (X = OCOCH3, OCOC3H7-i) and with tetramethyltin to give CH3(ClCH2)TlX compounds. R(ClCH2)TIX compounds (R = CH3, C6H5, p-CH3C6H4) undergo disproportionation in methanol to R2TlX and (ClCH2)2TlX compounds. 相似文献
5.
The relative stability of various organosulfur radicals is estimated by competitive elimination technique using tributyltin radical and acetophenone derivatives having two different sulfur substituents at α and α positions. 相似文献
6.
Toshikazu Kurosaki Osamu Takahashi Makoto Okawara 《Journal of polymer science. Part A, Polymer chemistry》1974,12(7):1407-1420
Polymers having stable pendant . radicals were synthesized through their precursor polymers by oxidizing them in air or by H2O2–Na2WO4. Hydrochlorides and sulfates of 4-methacryloylamino- and 4-methacryloyloxy-1-hydroxy-2,2,6,6-tetramethylpiperidines were synthesized as precursor monomers and polymerized by using α,α′-azobisisobutyronitrile under appropriate conditions to precursor polymers of high molecular weight: poly-4-methacryloylamino-/oxy-1-hydroxy-2,2,6,6-tetramethylpiperidinehydrochlorides and sulfates. The precursor polymers were converted to polymers having nitroxyl stable radicals, i.e., poly-4-methacryloylamino-/oxy-2,2,6,6-tetramethylpiperidine-1-oxyls, by oxidation in air or with H2O2–Na2WO4 without any main-chain scission. The structure of the resultant stable radical polymers was determined by infrared, ultraviolet, and ESR spectroscopy. Based on the results of spectroscopic analysis and Kjeldahl analysis, the transformation from precursors to nitroxyl stable radical polymers was found to be quantitative. Investigations on the applicability of polymeric nitroxyl radicals to oxidation-reduction reactions were attempted by means of polarography; the reduction half-wave potential was found to be ?1.16 V for the mercury pool. 相似文献
7.
Takeo Miyazawa Takeshi Endo Makoto Okawara 《Journal of polymer science. Part A, Polymer chemistry》1985,23(5):1527-1535
Some hindered amine polymers containing 2,2,6,6-tetramethylpiperidine structure were synthesized. A new monomer, 4-O-vinylbenzyl-2,2,6,6-tetramethylpiperidine, was homopolymerized and copolymerized with some vinyl monomers in the presence of AIBN as an initiator. The obtained amine polymers were oxidized with hydrogen peroxide to obtain the polymers having nitroxyl radical moiety. 相似文献
8.
An improved synthesis of methyl 4,6-0-benzylidene-2,3-dideoxy-2-nitro-β-D-erythro-hex-2-enopyranoside and its reactions with various nucleophiles are described; all the nucleophiles were found to approach exclusively or predominantly from the equatorial side of the molecule, giving the β-D-glucopyranoside derivatives as the major or exclusive product. The stereochemical course of approach of a nucleophile observed in the present reactions and in the literature are discussed. 相似文献
9.
Sung Il Hong Toshikazu Kurosaki Makoto Okawara 《Journal of polymer science. Part A, Polymer chemistry》1972,10(11):3405-3419
Polyoxime-urethanes have been synthesized from dioximes and diisocyanates, and their structures have been ascertained by elemental analysis and infrared spectroscopy. They can be represented by the general formula: These polymer films were photolyzed by using a high-pressure 100-W mercury lamp, and the rate of decomposition of the N? O bond was determined by use of ultraviolet and infrared spectra, or comparing the photochemical behavior with that of corresponding model compounds. Upon irradiating these polymers in the presence or absence of sensitizers or a hydrogen donor, there were obtained photolyzed polymers of low molecular weight, of which the molecular weights were estimated by observing the viscosity changes. To deduce the mechanism of photodegradation of polyoxime-urethane, photolysis of benzophenone oxime-phenyl urethane was investigated as a model compound. 相似文献
10.
Yoko Nambu Takeshi Endo Makoto Okawara 《Journal of polymer science. Part A, Polymer chemistry》1981,19(8):1937-1943
Reductive S-monoacylation of lipoamide with some carboxylic acids and tri-n-butylphosphine was carried out in acetonitrile to obtain the corresponding S-monoacylated compounds in excellent yield. This method was applied to the preparation of S-monoacylated dihydrolipoyl polymer with a neighboring thiol group. The acyl transfer from the polymer to cyclohexylamine was enhanced as much as 64 times by adding silver perchlorate. 相似文献