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Ring Positions (ring + position)
Selected AbstractsPhotochemistry of 4- and 5- phenyl substituted isoxazolesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 2 2005James W. Pavlik 5-Phenylisoxazole (4) and 4-phenylisoxazole (22) underwent phototransposition to 5-phenyloxazole (5) and 4-phenyloxazole (24) respectively. Labeling with deuterium or methyl confirmed that these phototranspositions occurred via the P4 pathway which involves only interchange of the N2 and C3 ring position. Thus, 4-deuterio-5-phenylisoxazole (4-4d), 4-methyl-5-phenylisoxazole (10), and 5-methyl-4-phenylisoxazole (23) phototransposed to 4-deuterio-5-phenyloxazole (5-4d), 4-methyl-5-phenyloxazole (11), and 5-methyl-4-phenyloxazole (25) respectively. In addition to phototransposition, isoxazoles 4, 10, and 23 also underwent photo-ring cleavage to yield benzoylacetonitrile (9), ,-benzoylpropionitrile (15), and aceto-,-phenylacetonitrile (26) respectively. Irradiation of 5-phenyl-3-(trifluoromethyl)isoxazole (16) in acetonitrile led to 5-phenyl-2-(trifluoromethyl)oxazole (17), the P4 phototransposition product. Irradiation of 16 in methanol led to a substantial decrease in the yield of 17 and to the formation of a mixture of (E) and (Z)-2-methoxy-2-(trifluoromethyl)-3-benzoylaziridines 18a and 18b. [source] Medium Effect on the Reaction of N -Butyl-2,4,6-trinitroaniline with NaOH,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 13 2007María Laura Salum Abstract The kinetics of the reaction of N -butyl-2,4,6-trinitroaniline (3) with NaOH have been studied in 10 and 60,% 1,4-dioxane/H2O at 25 °C. In both cases, several processes were observed. In 10,% 1,4-dioxane/H2O the only product formed was 2,4,6-trinitrophenol (4), whereas in 60,% 1,4-dioxane/H2O a mixture of 4 and 5,7-dinitro-2-propyl-1H -benzimidazole 3-oxide (5) was observed in ratios that depend on the HO, concentration. A mechanism involving the formation of , complexes through the addition of one or two HO, anions to unsubstituted ring positions is proposed for 2,4,6-trinitrophenol formation. The presence of these complexes was confirmed by NMR studies in 60,% [D8]1,4-dioxane/D2O. The mechanism suggested for the formation of the N -oxide includes the cyclization of an N -alkylidene-2-nitrosoaniline-type intermediate as the rate-determining step. The decrease in solvent polarity produces a decrease in the observed rate constant for the formation of 4 of about one order of magnitude making the cyclization reaction a competitive pathway. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] 6-(2-Hydroxybenzoyl)-5-(pyrrol-2-yl)-3H -pyrrolizineACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2003Sankar Prasad Dey The title compound, 2-hydroxyphenyl 5-(pyrrol-2-yl)-3H -pyrrolizin-6-yl ketone, C18H14N2O2, was isolated from the base-catalyzed 1:2 condensation of 2-hydroxyacetophenone with pyrrole-2-carbaldehyde. The pyrrole N,H and hydroxybenzoyl O,H groups are hydrogen bonded to the benzoyl O atom. The allylic C=C double bond of the 3H -pyrrolizine system is located between ring positions 1 and 2, the C atom at position 3 (adjacent to the N atom) being single bonded. [source] 9-Cyano-10-methylacridinium hydrogen dinitrateACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2002Olexyj M. Huta The title compound, C15H11N2+·HN2O6,, crystallizes in the monoclinic space group C2/c with four molecules in the unit cell. The planar 9-cyano-10-methylacridinium cations lie on crystallographic twofold axes and are arranged in layers, almost perpendicular to the ac plane, in such a way that neighbouring molecules are positioned in a `head-to-tail' manner. These cations and the hydrogen dinitrate anions are linked through C,H,O interactions involving four of the six O atoms of the anion and the H atoms attached to the C atoms of the acridine moiety in ring positions 2 and 4. The H atom of the hydrogen dinitrate anion appears to be located on the centre of inversion relating two of the four O atoms engaged in the above-mentioned C,H,O interactions. In this way, columns of either anions or cations running along the c axis are held in place by the network of C,H,O interactions, forming a relatively compact crystal lattice. [source] | ||||||||||