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Sodium Hydride (sodium + hydride)
Selected AbstractsSynthesis and Optoelectronic Properties of Nonpolar Polyrotaxane Insulated Molecular Wires with High Solubility in Organic Solvents,ADVANCED FUNCTIONAL MATERIALS, Issue 21 2008Michael J. Frampton Abstract Hydrophilic polyanionic conjugated polyrotaxanes are readily synthesized in water by Suzuki coupling, but their high polarity and ionic nature limit the potential applications of these materials. Here, we demonstrate three methods for transforming these polar polyelectrolytes into nonpolar lipophilic insulated molecular wires. A water-soluble polyfluorene- alt -biphenylene ,-cyclodextrin (CD) polyrotaxane was converted into nonpolar derivatives by methylation of the carboxylic acid groups with diazomethane and conversion of the hydroxyl groups of the CDs to benzyl ethers, trihexylsilyl ethers, benzoyl esters, and butanoate esters to yield polyrotaxanes that are soluble in organic solvents such as chloroform and cyclohexane. Elemental analysis, NMR spectroscopy, and gel permeation chromatography (GPC) data support the proposed structures of the organic-soluble polyrotaxanes. The extents of reaction of the polyrotaxane CD hydroxyl groups were 55% for trihexylsilyl chloride/imidazole; 81% for benzyl chloride/sodium hydride; 72% for benzoyl chloride/pyridine/4-dimethylaminopyridine; and 98% butanoic anhydride/pyridine/4-dimethylaminopyridine. Alkylation, silylation, and esterification increase the bulk of the encapsulating sheath, preventing interstrand aggregation, increasing the photoluminescence efficiency in the solid state and simplifying the time-resolved fluorescence decay. The organic-soluble polyrotaxanes were processed into polymer light-emitting diodes (PLEDs) from solution in nonpolar organic solvents, thereby excluding ionic impurities from the active layer. [source] An Efficient Approach for the Synthesis of N-1 Substituted HydantoinsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 11 2008Vinod Kumar Abstract An efficient three-step route for the synthesis of N - 1 alkyl/aryl-substituted hydantoins was developed from inexpensive commercially available substrates. The reaction of amines with cyanogen bromide takes place to give monoalkyl/aryl cyanamides. This on treatment with methyl bromoacetate in the presence of sodium hydride in tetrahydrofuran affords methyl N -cyano- N -alkyl/arylaminoacetate, which undergoes hydrolysis and cyclization in the presence of 50,% H2SO4 to afford N - 1 substituted hydantoins in very good-to-excellent yields. Wide varieties of final products having primary, secondary, tertiary, and aryl substituents at the N - 1 position were successfully synthesized by this method. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Synthesis and insecticidal evaluation of novel N-oxalyl derivatives of diacylhydrazines containing methylcarbamate moietiesHETEROATOM CHEMISTRY, Issue 6 2005Chunhui Mao A series of new N -oxalyl derivatives of diacylhydrazines containing methylcarbamate moieties were synthesized by the reaction of N -oxalyl chloride of N -methylcarbmates with N - tert -butyl- N,N,-diacylhydrazines in the presence of sodium hydride. The reaction of oxalyl chloride with N - tert -butyl- N, N,-diacylhydrazines to yield 1,3,4-oxadiazole and 4- tert -butyl-2-substituted-phenyl-4H -1,3,4-oxadiazine-5,6-dione was found, and the reaction was studied in some detail. The title compounds were evaluated for molting hormone mimicking activity. The results of bioassay showed that the title compounds exhibit moderate larvicidal activities, and toxicity assays indicated that these compounds can induce a premature, abnormal, and lethal larval molt. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:472,475, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20135 [source] A convenient synthesis of substituted 3-alkoxycarbonyl-,,,-unsaturated esters with predominant Z-selectivityHETEROATOM CHEMISTRY, Issue 3 2003Yanchang Shen The consecutive reaction of bis[2,2,2-trifluoroethyl]phosphite with sodium hydride, dimethyl maleate, and aldehydes gives 3-alkoxycarbonyl-,,,-unsaturated esters with predominant Z-selectivity in 62,94% yields (Z/E = 85,60:15,40). The Z- and E-isomer can be separated conveniently by column chromatography. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:276,279, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10142 [source] Synthesis and antifungal activity of spiro[cyclopropane-1,4,-pyrazol-3-one] derivativesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 6 2008Hiroshi Maruoka A series of new spiro[cyclopropane-1,4,-pyrazol-3-one] derivatives 3a-h were synthesized by the reaction of 4-arylidene-3H -pyrazol-3-one 1 with secondary and tertiary carbanions derived from a methylene and methine group bearing both a leaving group and electron-withdrawing group, e.g. methyl chloroacetate, ethyl chloroacetate, isopropyl chloroacetate, tert -butyl chloroacetate, chloroacetonitrile, 2-chloro- N,N -diethylacetamide, methyl 2-chloropropionate and 2-chloropropionitrile, in the presence of sodium hydride. All the synthesized compounds 3a-h were active against Candida albicans with MIC , 25 ,g/mL in vitro. [source] Facile regiospecific syntheses of N -,,N -1(,)-dialkyl-l-histidinesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 6 2007Surendra Kumar Nayak Two diverse methodologies describe the first synthesis of suitably protected N -,,N -1(,)-dialkyl-Lhistidine derivatives. Synthesis of suitably protected N -,,N -1(,)-dialkyl-L-histidines 7-9 containing different alkyl groups at the N -, and N -1(,) positions was achieved in four steps starting from L-histidine methyl ester. Whereas, in the one-step alternate route N -,-Boc-L-histidine methyl ester upon direct and simultaneous N -, and N -1(,) alkylation with various alkyl halides in the presence of sodium hydride in DMF easily afforded N -,,N -1(,)-dialkyl-L-histidines 14 containing identical alkyl group at the N -, and N -1(,) positions in high yields. Both procedures allowed facile entry to methyl and other higher alkyl groups at the N -,-position of the histidine ring [source] Synthesis of 2,4-diaminopyrido[2,3- d]pyrimidines and 2,4-diamino-quinazolines with bulky dibenz[b,f]azepine and dibenzo[a,d]-cycloheptene substituents at the 6-position as inhibitors of dihydrofolate reductases from pneumocystis carinii, toxoplasma gondii, and mycobacterium avium,JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 4 2000Andre Rosowsky The synthesis of four previously undescribed 2,4-diaminopyrido[2,3- d]pyrimidines (3,4) and 2,4-diaminoquinazolines (5,6) with a bulky tricyclic aromatic group at the 6-position is described. Condensation of dibenz[b,f]azepine with 2,4-diamino-6-bromomethylpyrido[2,3- d]pyrimidine (8) and 2,4-diamino-6-bromomethylquinazoline (17) in the presence of sodium hydride afforded N -[(2,4-diaminopyrido[2,3- d]-pyrimidin-6-yl)methyl]dibenz[b,f]azepine (3) and N -[(2,4-diaminoquinazolin-6-yl)methyl]dibenz[b,f]-azepine (4), respectively. Condensation of 5-chlorodibenzo[a,d]cycloheptene (19) and 5-chloro-10,11-dihydrodibenzo[a,d]cycloheptene (20) with 2,4,6-triaminoquinazoline (13) afforded 5-[(2,4-diamino-quinazolin-6-yl)amino]-5H -dibenzo[a,d]cycloheptene (5) and the corresponding 10,11-dihydro derivative (6), respectively. The bromides 8 and 17, as hydrobromic acid salts, were obtained from the corresponding nitriles according to a standard three-step sequence consisting of treatment with Raney nickel in formic acid followed by reduction with sodium borohydride and bromination with dry hydrogen bromide in glacial acetic acid. Compounds 3,6 were evaluated in vitro for the ability to inhibit dihydrofolate reductase from Pneumocystis carinii, Toxoplasma gondii, Mycobacterium avium, and rat liver. Compounds 3 and 4 were potent inhibitors of all four enzymes, with IC50 values in the 0.03,0.1 ,M range, whereas 5 was less potent. However the selectivity of all four compounds for the parasite enzymes relative to the rat enzyme was<10-fold, whereas the recently reported lead compound in this series, N -[(2,4-diaminopteridin-6-yl)methyl]dibenz[b,f]azepine (1) has > 100-fold selectivity for the T. gondii and M. avium enzyme and 21-fold selectivity for the P carinii enzyme. [source] Synthesis of 14C-labelled myosmine, [2,- 14C] -3-(1-pyrrolin-2-yl)pyridineJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 5 2003Stefan Tyroller Abstract 14C-Labelled myosmine ([2,- 14C]-3-(1-pyrrolin-2-yl)pyridine) was synthesized for autoradiography studies starting from [carboxyl- 14C]-nicotinic acid by initial esterification of the latter in the presence of 1,1,1-triethoxyethane. Without any purification the ethyl nicotinate formed was directly reacted with N -vinyl-2-pyrrolidinone in the presence of sodium hydride, yielding 14C-labelled myosmine. The product was purified by silica gel column chromatography. The radiochemical yield was 15% and the specific activity 55.2 mCi/mmol. Copyright © 2003 John Wiley & Sons, Ltd. [source] Titanium-mediated living radical styrene polymerizations.JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 6 2006Abstract The effects of solvents, additives, ligands, and solvent in situ drying agents as well as catalyst and initiator concentrations have been investigated in the Cp2TiCl-catalyzed radical polymerization of styrene initiated by epoxide radical ring opening. On the basis of the solubilization of Cp2Ti(III)Cl and the polydispersity of the resulting polymer, the solvents rank as follows: dioxane , tetrahydrofuran > diethylene glycol dimethyl ether > methoxybenzene > diphenyl ether , bulk > toluene , pyridine > dimethylformamide > 1-methyl-2-pyrrolidinone > dimethylacetamide > ethylene carbonate, acetonitrile, and trioxane. Alkoxide additives such as aluminum triisopropoxide and titanium(IV) isopropoxide are involved in alkoxide ligand exchange with the epoxide-derived titanium alkoxide and lead to broad molecular weight distributions, whereas similarly to strongly coordinating solvents, ligands such as bipyridyl block the titanium active site and prevent the polymerization. By contrast, softer ligands such as triphenylphosphine improve the polymerization in less polar solvents such as toluene. Although mixed hydrides such as lithium tri- tert -butoxyaluminum hydride, sodium borohydride, and lithium aluminum hydride react with bis(cyclopentadienyl)titanium dichloride to form mixed titanium hydride species ineffective in polymerization control, simple hydrides such as lithium hydride, sodium hydride, and especially calcium hydride are particularly effective as in situ trace water scavengers in this polymerization. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2015,2026, 2006 [source] The cyclization transformation of the sulfonylurea herbicide flupyrsulfuron in the soil of winter wheat cropsPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 8 2003Jean Rouchaud Abstract The synthesis of 1-(4,6-dimethoxypyrimidine-2-yl)-7-trifluoromethyl-1,2,3,4-tetrahydropyrido[2,3- d]pyrimidin-2,4-dione has been carried out in such a way that the dimethoxypyrimidine substituent was unambiguously in position 1 of the pyrido[2,3- d]pyrimidine ring. This regioisomer was obtained by cyclization with phosgene of 2-(4,6-dimethoxypyrimidin-2-ylamino)-6-trifluoromethylnicotinamide which had previously been ionized with sodium hydride. It was shown to be identical to the metabolite generated in the soil of winter wheat crops treated previously with the sulfonylurea herbicide flupyrsulfuron-methyl [(methyl 2-(4,6-dimethoxypyrimidin-2-ylcarbamoylsulfamoyl)-6-trifluoromethylnicotinate]. The position of the dimethoxypyrimidine substituent had not previously been assigned unambiguously to positions 1 or 3 of the pyrido[2,3- d]pyrimidine ring. The regioisomer was also identical to the cyclization compound generated chemically from flupyrsulfuron in a sterile water buffer at pH 9. The metabolism pathways of flupyrsulfuron in soil are discussed in the light these structure determinations and compared with the soil metabolism pathways frequently observed with other sulfonylurea herbicides. Copyright © 2003 Society of Chemical Industry [source] | |||||||||||||