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Borohydride reduction of pyridinium salts. IV. Simultaneous low-temperature formation of (2+2) and (4+2) cycloadducts in the reduction of 1-methyl-4-cyanopyridinium iodide.
No full textThe redn. of 1-methyl-4-cyano-pyridinium iodide at -45 in 0.8N methanolic NaOH yielded 60% trans-cis-trans-7,8-dicyano-4,11-dimethyl-4,11-diazatricyclo-[6.4.0.02.7] dodeca-5,9-diene (I) contg. only traces of II. Redns. performed at temps. increasing from -45 to -20, yielded ppts. contg. progressively more II, until at > -20 only II was present in the ppt. I was very labile and, in the solid state, at 15-20 was quickly converted to II. If I was rapidly poured into 6N HCl at -45, an insol. product which was sufficiently stable for characterization was immediately formed
Borohydride reduction of pyridinium salts. V. Thermal dimerization of 1,6-dihydro-1-methylpyridine-2-carbonitrile.
No full textThe 1,6-dihydropyridine I, obtained by NaBH4 redn. of 2-cyano-1-methylpyridinium iodide, undergoes a thermal dimerization to give the cyclobutane deriv. II. II rearranges, by heating, to the isomeric ethenonaphthyridine III (R = H). Label scrambling observed at 110 in III (R = H) reveals a degenerate thermal [3.3] sigmatropic shift
behavioral and electroencephalographic effects of choline esters able to delivery and release choline into the brain of animal model of Alzheimer disease.
No full textbehavioral and electroencephalographic effects of choline esters able to delivery and release choline into the brain of animal models of alzheimer's disease
No full textpyrroloquinolinequinone : a versatile biological electron carrier
No full textThe redox properties of the pyrrolo quinoline quinone (PQQ) were studied by means of the specific one-electron reductans NAD dimers, (NAD)2 and (NADP)2. PQQ and (NAD)2 or (NADP)2 give rise to a redox process whose products are pyrrolo quinoline quinol (PQQH2) and coenzymes NAD+ or NADP+. The process implies a two-step one electron transfer via the intermediate pyrrolo quinoline semiquinone radical (PQQ
ON THE STRUCTURE OF INTERMEDIATE ADDUCTS ARISING FROM DITHIONITE REDUCTION OF PYRIDINIUM SALTS : A NOVEL CLASS OF DERIVATIVES OF THE PARENT SULFINIC ACIDS.
No full text13C and 17O NMR spectroscopy show that adducts arising from dithionite reduction of 3- or 3,5-cyano- or carbamoyl-substituted pyridinium salts to the corresponding 1,4-dihydropyridines, are S-anions of esters of the simplest parent sulfinic acid. A pathway for formation of the 1,4- dihydropyridines, involving an intramolecular hydride transfer, is suggested
Dihydropyridines and pyridones from 3-cyano-1-methylpyridinium iodide in aqueous sodium hydroxide.
No full text3-Cyano-1-methylpyridinium iodide added to aq. NaOH and stirred for 2 h gave the isomeric 1,4-, 1,2-, and 1,6-dihydropyridines in the ratio 11:2:1, 5-cyano-1-methyl-2-pyridone, and 3-cyano-1-methyl-2-pyridone which were extd. with CH2Cl2. The aq. layer, after neutralization with H2SO4, gave 2-cyano-glutaconaldehyde Na enolate, shown by NMR to exist in a mesomeric state. The intermediate 2-hydroxydihydropyridines behaved as reducing agents toward the pyridinium cation, involving H- transfer, as well as undergoing the normal ring opening reaction
Borohydride reduction of pyridinium salts. III.Formation of a Diels-Alder adduct in the reduction of 1-methyl-4-cyanopyridinium iodide.
No full textNaBH4 redn. of 1-methyl-4-cyanopyridinium iodide (I) in 1:1 H2O-MeOH gave 1-methyl-4-cyano-1,2,5,6-tetrahydropyridine, whereas similar redn. of I in a 0.8M NaOH-MeOH soln. gave a tricyclododecadiene (II)
regioselectivity of dimerization of 4-methyl or 6-methyl substituted pyridinyl radicals arising from the one electron electrochemical reduction of NAD(P) model compounds : a 1H-NMR study.
No full textProcedimento Elettrochimico per la Preparazione di Beta-lattami, Utili Intermedi per la Produzione di Antibiotici
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