- Triazolopyridines. Part 30.1 Hydrogen transfer reactions; Pyridylcarbene formation
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The transfer hydrogenation reaction of [1,2,3]triazolo[1,5-a]pyridines with Pd/C/Zn or Pd(OH)2/C/Zn in water, ethanol or water/ethanol mixture has been explored. 4,5,6,7-Tetrahydrotriazolopyridines were obtained in good to medium yields. In addition, under the same conditions 2-substituted pyridines were also formed as a result of intermediate pyridylcarbene formation, by triazole ring opening and loss of nitrogen.
- Abarca, Belen,Adam, Rosa,Alom, Shamim,Ballesteros, Rafael,Lopez-Molina, Sonia
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p. 175 - 186
(2014/03/21)
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- REACTIVITY OF HETEROAROMATIC ALDEHYDES WITH LOW VALENT TITANIUM
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Behaviour of various aromatic heterocycles under dicarbonylic coupling with low valent titanium was studied.The results showed that the electron donating properties of the ring affect the degree of oxidation of the coupled compound.
- Castedo, Luis,Cid, M. Magdalena,Dominguez, Rosa,Seijas, Julio A.,Villaverde, M. Carmen
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p. 1271 - 1274
(2007/10/02)
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- ELEMENTAL SULFUR REACTIONS WITH 2-PICOLINE
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A study of the reaction of the elemental sulfur with 2-picoline is reported.The process was carried out at the boiling point of the 2-picoline under argon.After removing unreacted solids, the reaction products were identified by means of LC, GC and GC-MS.The following products have been identified by mass spectrometry: 1,2-di/2-pyridyl/-ethane, 1,2-di/2-pyridyl/-ethene, 2-methyl-x-pyridines, 2-mercapto-methyl--pyridines, 1-mercapto-1,2-di/2-pyridyl/-ethane, 5,6-di/2-pyridyl/-5H-cyclopenta-pyridine, 5,6-di/2-pyridyl/-7H-cyclopentapyridine, 1,2,3-tri/2-pyridyl/-propane, 1,2-di/2-pyridyl/-1--ethane, 5,6-di/2-pyridyl/-7--7H-cyclopentapyridine, 5,6-di/2-pyridyl/-5--5H-cyclopentapyridine, dipyridyl>> sulfide and dipyridyl>> disulfide.
- Gleich, Edward,Warnke, Zydmunt
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p. 211 - 222
(2007/10/02)
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- HOMOLYTIC PYRIDYLETHYLATION OF CYCLOHEXANE AND TETRALIN
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The homolytic pyridylethylation of cyclohexene and tetraline with 2-vinylpyridine under conditions of peroxide and thermal initiation was investigated.In addition to the main reaction products, i.e., cycloalkylethylpyridines (1 : 1 adducts), compounds indicating rearrangement of the radicals with H migration were also isolated and identified.
- Il'yasov, E.A.,Galust'yan, G.G.
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p. 326 - 330
(2007/10/02)
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- PH-Functional Phosphanes with 2-Pyridyl Substituents in α- or β-Position 2-C5H4N-n-PRH (R = H, iPr, tBu, Ph, 2-C5H4N-n; n = 1, 2)
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PH-functional phosphanes containing a 2-pyridyl substituent in α- or β-position to phosphorus, e.g. 2-C5H4N-n-PRH (R = H, iPr, tBu, Ph; n = 1, 2) have been obtained.The reactivity of the PH-groups can be employed for the synthesis of tridentate NPN-hybrid donors, 2PR (R = H, Ph).The phosphanes 2-C5H4N-n-PRH behave as monodentate ligands in transition metal complexes and form labile chelate ring systems.They may bridge metal-metal bonds to form seven membered ring systems, e.g.Mo2PC3N.The coordination of the N-donor of the ligands 2-C5H4N- n-PRH to a transition metal atom is indicated by a lowfield shift and a small (31)P-(13)C-splitting of the 13C NMR signal of carbon atom 6 in the pyridin ring system. - 2-Pyridyl Substituent, Reactions at PH-Functions, Chelate Complexes, Ligand Replacement, 13C NMR Spectra
- Spiegel, Gerd U.,Stelzer, Othmar
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p. 579 - 588
(2007/10/02)
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- Excimer Emission in Protonated Pyridine Systems. 2. Excimer Emission of Protonated Dipyridylalkanes in Solution at Room Temperature and 77 K
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Emission properties of (2-pyridyl)-(CH2)n-(2-pyridyl) (n = 2, 3, 5, and 7) and (4-pyridyl)-(CH2)n-(4-pyridyl) (n = 2, 3, and 5) were studied in solution in the presence of trifluoroacetic acid at room temperature and 77 K.At room temperature, only 1,3-di(2-pyridyl)propane exhibits a very weak fluorescence at approximately 6900 cm-1 to the red of the normal fluorescence.This band is ascribed to an intramolecular excimer fluorescence between the protonated pyridine moieties.However, 4,4'-dipyridylalkanes do not fluoresce.At 77 K, being specific to a mixed solvent of tetrahydrofuran, methanol, and methyltetrahydrofuran (4:3:1 by volume), the protonated 2,2'-dipyridylalkanes exhibit a structureless band around around 325 nm besides the normal fluorescence band, but they exhibit no excimer fluorescence.On the other hand, the protonated 4,4'-dipyridylalkanes apparently exhibit only a structureless band around 325 nm.The 325-nm fluorescence band comes from a dimerlike excimer in which the protonated pyridine moieties interact intermolecularly in the excited state.The efficiency of the dimerlike excimer formation is independent of the length of methylene chain.From studies on the effects of solvent and temperature on the dimerlike excimer emission, it is found that the formation of the dimerlike excimer is strongly related to a solvent cage effect.
- Handa, Takashi,Utena, Yoshio,Yajima, Hirofumi
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p. 5150 - 5154
(2007/10/02)
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- FREE-RADICAL PYRIDYLETHYLATION OF ARYLALKANES
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2-(3-Arylpropyl)pyridines were synthesized in 30-54percent yields by the free-radical addition of toluene, o-, m-, and p-xylenes, and mesitylene to 2-vinylpyridine at 250-350 deg C.The products of rearrangement of the intermediate adduct radical with 1,3-H migration were isolated and identified.
- Galust'yan, G. G.,Il'yasov, E. A.,Kadyrov, Ch. Sh.
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p. 307 - 310
(2007/10/02)
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- Flash Vacuum Pyrolysis of Substituted Pyridine N-Oxides and Its Application to Syntheses of Heterocyclic Compounds
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Flash vacuum pyrolysis of 2-picoline N-oxide gave 2-picoline, pyridine, 2-ethylpyridine, 2-vinylpyridine, 2-pyridylmethanol, bis(2-pyridyl)methane, 1,2-bis(2-pyridyl)ethane, and 1,2-bis(2-pyridyl)ethylene.These reactions are explained by intermediary participation of the 2-picolyl radical.Flash vacuum pyrolysis of methyl-substituted 2-benzylpyridine N-oxides led to methyl-substituted pyridoindoles or to benzoquinoline in moderate yields.
- Ohsawa, Akio,Kawaguchi, Takayuki,Igeta, Hiroshi
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p. 3497 - 3503
(2007/10/02)
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- Flash Vacuum Pyrolysis of Aromatic Oximes
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Flash vacuum pyrolisis (FVP) of benzaldoximes and aryl ketoximes afforded nitriles and additional aromatic compounds which were presumably generated from intermediary iminyl radicals.The FVP also gave benzoxazoles, which were presumably formed from iminoxyl radicals.Benzyl ketoximes afforded indoles together with fragmentation products of the iminyl radicals.Keyword---gas-phase pyrolysis; flash vacuum pyrolysis; FVP; flash thermolysis; oxime; iminyl radical; iminoxyl radical; substituted indole; benzoxazole; mass spectra
- Ohsawa, Akio,Kawaguchi Takayuki,Igeta Hiroshi
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p. 4352 - 4358
(2007/10/02)
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- NEW SYNTHETIC METHOD OF PARACYCLOPHANE, BENZOCYCLOBUTENE, AND LEPIDOPTRENE: PYROLYSIS OF ARYLMETHYL PHENYL SELENIDES
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The flash vacuum pyrolysis of benzyl phenyl selenides gave bibenzyls and diphenyl diselenide in excellent yields.This type of reaction was successfully applied to the synthesis of the title compounds.
- Higuchi, Hiroyuki,Sakata, Yoshiteru,Misumi, Soichi,Otsubo, Tetsuo,Ogura, Fumio,Yamaguchi, Hachiro
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p. 627 - 630
(2007/10/02)
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- FLASH VACUUM PYROLYSIS OF 2-PICOLINE N-OXIDE. FORMATION OF 2-PICOLYL RADICAL
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The flash vacuum pyrolysis of 2-picoline N-oxide was found to give 2-picoline, pyridine, 2-vinylpyridine, bis(2-pyridyl)methane, and 1,2-bis(2-pyridyl)ethane.From the mechanistic consideration of the formation of these products, intermediacy of 2-picolyl radical (i.e., 2-pyridylmethyl radical) is strongly suggested.Keywords: flash vacuum pyrolysis; thermolysis; picoline N-oxides; heterocycles; radical reaction; radical coupling; picolyl radical; pyridylmethyl radical
- Ohsawa, Akio,Kawaguchi, Takayuki,Igeta, Hiroshi
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p. 1481 - 1483
(2007/10/02)
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