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Pyrimidine Ring (pyrimidine + ring)
Selected AbstractsChemInform Abstract: Fluorine-Containing Quinazolines Annulated at the Pyrimidine Ring.CHEMINFORM, Issue 41 2010E. V. Nosova Abstract The title compounds are synthesized by the reaction of 2- and 4-hydrazino-substituted quinazolines with aldehydes and subsequent oxidative cyclization or by alkylation of 2-alkylthio-4(3H)-quinazolinones with bromoethanol and ipso-substitution of the alkylthio group. [source] Tautomerism of Diazepines Fused with Pyrimidine Rings.CHEMINFORM, Issue 26 2003Valentin A. Chebanov Abstract For Abstract see ChemInform Abstract in Full Text. [source] Synthesis of 1,2-Disubstituted Carbocyclic Nucleoside Analogues of CytidineHELVETICA CHIMICA ACTA, Issue 5 2006José González-Moa, María Abstract The synthesis of new 1,2-disubstituted, five- or six-ring-carbocyclic nucleoside analogues of cytidine, compounds 1 and 2a,d, are described. These compounds were obtained by aminolysis, starting from the corresponding uracil derivative, via nucleophilic displacement of a triazolyl (Scheme,1) or a (2,4,6-triisopropylphenyl)sulfonyl (TPS) group (Scheme,2) at 4-position of the pyrimidine ring. [source] Study on the reaction of methyl N -Methyl- N -(6-substituted-5-nitropyrimidin-4-yl)glycinates with sodium alkoxidesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 2 2006Inga Susvilo Methyl N -methyl- N -(6-substituted-5-nitropyrimidin-4-yl)glycinates (4a-n), obtained from 6-substituted-4-chloro-5-nitropyrimidines and sarcosine methyl ester (methyl 2-(methylamino)acetate), in the reaction with sodium alkoxides underwent transformations to give different products. N -methyl- N -(5-nitropyrimidin-4-yl)glycinates (4a,i,j) bearing amino and arylamino groups in the position 6 of the pyrimidine ring gave corresponding 6-substituted-4-methylamino-5-nitrosopyrimidines (5a,i,j). In the reaction of N -(6-alkylamino-5-nitropyrimidin-4-yl)- N -methylglycinates (4b,f-h) with sodium alkoxides the corresponding 6-alkylamino-4-methylamino-5-nitrosopyrimidines (5b,f-h) and 5-hydroxy-8-methyl-5,8-dihydropteridine-6,7-diones (6b,f-h) were formed. The main products of the reaction of N -(6-dialkylamino-5-nitropyrimidin-4-yl)- N -methylglycinates (4c-e,k,l), after work-up, were the corresponding 6-dialkylamino-9-methylpurin-8-ones (7c-e,k,l) and 8-alkoxy-6-dialkylamino-9-methylpurines (9c,1,10c,l). Methyl N -methyl- N -{[6-(2-methoxy-oxoethyl)thio]-5-nitropyrimidin-4-yl}glycinate (4n) under the same conditions gave methyl 7-methylaminothiazolo[5,4- d]pyrimidine-2-carboxylate (13). Mechanisms of the observed transformations are discussed. [source] Preparation of new N6, 9-disubstituted 2-phenyl-adenines and corresponding 8-azaadenines.: A feasibility study for application to solid-phase Synthesis.JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 4 2004A suitably substituted pyrimidine 1 was converted to a number of title compounds. Nucleophilic substitu tion involving the chlorine atoms in 1 by treatment with phenylmethanethiol yielded 2 or 3, depending on the reaction temperature. Treatment of 3 with an amine afforded 6-phenylmethanesulfanyl-N4 -substituted-2-phenyl-pyrimidine-4,5-diamines 4,7. These pyrimidines were converted into 2-phenylpurines 8,11 and 2-phenyl-8-azapurines 12,14, by treatment with triethyl orthoformate in the presence of hydrochloric acid (or acetic anhydride), or with potassium nitrite and acetic acid respectively. The thioether function on C(6) was then converted into a sulfonyl group by oxidation with m -chloroperoxybenzoic acid affording purines 15,18 and their 8-azaanalogs 19,21; these compounds, as crude products, were treated with an amine to yield the corresponding adenines 22,25 or 8-azaadenines 26,31. All reactions were performed under conditions com patible with the possible use of a thiomethyl resin in place of phenylmethanethiol to bind the pyrimidine ring of 1 to a solid phase. [source] Aminolysis of methoxy groups in pyrimidine derivatives.JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 1 2002Activation by 5-nitroso The nucleophilic substitution of 2-mefhoxy groups in pyrimidine derivatives was strongly activated by introduction of a 5-nitroso group on to the pyrimidine ring. The aminolysis of several 2-methoxy-5-nitrosopyrimidine derivatives was performed at room temperature in hydroxylic as well as in non-hydroxylic media with different primary amines in short time and good yields. The aminolysed substrates include 6-[(per- O -acetyl)glycosyl]aminopyrimidines which afforded the corresponding 2-aminopyrimidines without harming the acetyl protecting groups of the sugar moiety. [source] Research on heterocyclic compounds.JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 5 2000XLII. The Vilsmeier reaction on imidazo[1,2- a]pyrimidine ring is reported. The 3-formyl derivative obtained is oxidized to yield the corresponding carboxylic acid. [source] Synthesis and biological evaluation of carbon-11-labeled acyclic and furo[2,3-d]pyrimidine derivatives of bicyclic nucleoside analogues (BCNAs) for structure,brain uptake relationship study of BCNA tracersJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 3 2008Satish K. Chitneni Abstract We reported earlier on radiolabeled alkoxyphenyl bicyclic nucleoside analogues (BCNAs) as potential positron emission tomography (PET) reporter probes for imaging of varicella zoster virus thymidine kinase (VZV-tk) gene in vivo. Despite their favorable physicochemical properties, these tracers are not taken up in the brain in mice. In order to probe the role of the deoxyribose sugar moiety in blood-brain barrier (BBB) penetration of these molecules, we have synthesized and evaluated a carbon-11-labeled acyclic bicyclic nucleoside derivative ([11C]-10) where the 2,-deoxyribose sugar is replaced with a (2-hydroxyethoxy)methyl group and [11C]-12, which has no sugar moiety but a [11C]methyl group on the N-3 position of the pyrimidine ring. Methylation was achieved on the phenol ([11C]-10) or the N-3 position ([11C]-12) using [11C]methyl triflate (radiosynthesis). The (non-radioactive) acyclic O -methyl derivative 10 has rather poor affinity for the enzyme VZV-TK in vitro (IC50: 430,µM), compared with the moderate affinity of the BCNA-base N -methyl derivative 12 (IC50: 79,µM). In normal mice, none of the two tracers ([11C]-10 or [11C]-12) showed significant uptake in the brain, suggesting that compounds containing a furo[2,3- d]pyrimidine system do not cross the BBB. Copyright © 2008 John Wiley & Sons, Ltd. [source] Complexation of sulfonamides with ,-cyclodextrin studied by experimental and theoretical methodsJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 7 2010Ariana Zoppi Abstract The complex formation between three structurally related sulfonamides (sulfadiazine (SDZ), sulfamerazine (SMR), and sulfamethazine (SMT)) and ,-cyclodextrin (,-CD) was studied, by exploring its structure affinity relationship. In all the cases, 1:1 stoichiometries were determined with different relative affinities found by phase solubility (SDZ:,-CD,>,SMR:,-CD,>,SMT:,-CD) and nuclear magnetic resonance (NMR) (SMT:,-CD,>,SMR:,-CD,>,SDZ:,-CD) studies. The spatial configurations determined by NMR were in agreement with those obtained by molecular modeling, showing that SDZ included its aniline ring into ,-CD, while SMR and SMT included the substituted pyrimidine ring. Energetic analyses demonstrated that hydrophobicity is the main driving force to complex formation. © 2010 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:3166,3176, 2010 [source] H2O2 -mediated oxidation of tetrahydrobiopterin: Fourier transform Raman investigations provide mechanistic implications for the enzymatic utilization and recycling of this essential cofactorJOURNAL OF RAMAN SPECTROSCOPY, Issue 8 2002Jeremy Moore The oxidation of (6R)- L - erythro -5,6,7,8-tetrahydrobiopterin (6BH4) by H2O2 was examined by Fourier transform Raman spectroscopy. Initial investigations indicated that oxidation proceeds by incorporation of the H2O2 into the 6BH4 molecule without the formation of any additional water. In addition, the pyrimidine ring is affected with the shift of the double bond from the N1,C2 to the C2,N3 position. Such rearrangements of this double bond are observed after the production of either a carbinolamine or quinonoid species. Using deuterium exchange experiments, it was possible to substantiate that the oxidation of 6BH4 initially proceeds by the formation of a 4a-OH-carbinolamine intermediate prior to its spontaneous dehydration yielding the quinonoid dihydro species (qBH2). Furthermore, the hydrogen on the hydroxyl group of the carbinolamine interacts with the oxygen of the carbonyl group at the C4 position of the pyrimidine ring. It is proposed that this interaction facilitates the dehydration of the carbinolamine, thus explaining its instability. Furthermore, a mechanism for the dehydration reaction is suggested, wherein the 4a-hydroxyl group forms an H-bond to the carbonyl group, thus making the oxygen of the hydroxyl group more susceptible to attack by the proton at position N5 of the pyrazine ring, resulting in qBH2 production concomitant with the loss of a water molecule. Upon increasing the concentration of H2O2 the qBH2 converts to 7,8-BH2, which is further oxidized to L -biopterin. Taken together, our results do not support an earlier proposed mechanism implicating a hydroperoxide intermediate in this oxidation reaction. Copyright © 2002 John Wiley & Sons, Ltd. [source] Degradation of the sulfonylurea herbicide LGC-42153 in flooded soilPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 11 2003Jin Kim Abstract LGC-42153, 2-fluoro-1-[3-(4,6-dimethoxypyrimidin-2-ylcarbamoylsulfamoyl)pyridin-2-yl]propyl methoxyacetate, is a new sulfonylurea herbicide for use in rice. Its breakdown and metabolism were studied in soil under flooded condition using radioactive tracers labelled at either the propyl group or the pyrimidine ring. The half-life of LGC-42153 was approximately 3.0 days. The mass balance over 120 days ranged from 94.0 to 104.2% of applied radiocarbon, and no significant amount of volatiles or [14C]carbon dioxide were observed. Solvent non-extractable radiocarbon reached 11 , 14% of applied radiocarbon at 120 days after treatment. The major metabolic reaction was the cleavage of the carboxyl ester bond to give 1-(4,6-dimethoxypyrimidin-2-yl)-3-[2-(1-hydroxy-2-fluoropropyl)pyridine-3-sulfonyl]urea, which underwent hydrolysis of the sulfonylurea bridge giving 2-(1-hydroxy-2-fluoro)propyl-3-pyridinesulfonamide and 4,6-dimethoxy-2-aminopyrimidine. Copyright © 2003 Society of Chemical Industry [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] 2,-Deoxy-5-propynyluridine: a nucleoside with two conformations in the asymmetric unitACTA CRYSTALLOGRAPHICA SECTION C, Issue 12 2009Simone Budow The title compound, 1-(2-deoxy-,- d - erythro -pentofuranosyl)-5-(prop-1-ynyl)pyrimidin-2,4(1H,3H)-dione, C12H14N2O5, shows two conformations in the crystalline state: conformer 1 adopts a C2,- endo (close to 2E; S -type) sugar pucker and an anti nucleobase orientation [, = ,134.04,(19)°], while conformer 2 shows an S sugar pucker (twisted C2,- endo,C3,- exo), which is accompanied by a different anti base orientation [, = ,162.79,(17)°]. Both molecules show a +sc (gauche, gauche) conformation at the exocyclic C4,,C5, bond and a coplanar orientation of the propynyl group with respect to the pyrimidine ring. The extended structure is a three-dimensional hydrogen-bond network involving intermolecular N,H...O and O,H...O hydrogen bonds. Only O atoms function as H-atom acceptor sites. [source] Two novel silver(I) coordination polymers: poly[(,2 -2-aminopyrimidine-,2N1:N3)bis(,3 -thiocyanato-,3S:S:S)disilver(I)] and poly[(2-amino-4,6-dimethylpyrimidine-,N)(,3 -thiocyanato-,3N:S:S)silver(I)]ACTA CRYSTALLOGRAPHICA SECTION C, Issue 10 2009Geng-Geng Luo 2-Aminopyrimidine (L1) and 2-amino-4,6-dimethylpyrimidine (L2) have been used to create the two novel title complexes, [Ag2(NCS)2(C4H5N3)]n, (I), and [Ag(NCS)(C6H9N3)]n, (II). The structures of complexes (I) and (II) are mainly directed by the steric properties of the ligands. In (I), the L1 ligand is bisected by a twofold rotation axis running through the amine N atom and opposite C atoms of the pyrimidine ring. The thiocyanate anion adopts the rare ,3 -,3S coordination mode to link three tetrahedrally coordinated AgI ions into a two-dimensional honeycomb-like 63 net. The L1 ligands further extend the two-dimensional sheet to form a three-dimensional framework by bridging AgI ions in adjacent layers. In (II), with three formula units in the asymmetric unit, the L2 ligand bonds to a single AgI ion in a monodentate fashion, while the thiocyanate anions adopt a ,3 -,1N,,2S coordination mode to link the AgL2 subunits to form two-dimensional sheets. These layers are linked by N,H...N hydrogen bonds between the noncoordinated amino H atoms and both thiocyanate and pyrimidine N atoms. [source] 5-Nitro- N4,N6 -diphenylpyrimidine-4,6-diamine: polarized molecules linked into ,-stacked chains via three-centre C,H...(O)2 hydrogen bondsACTA CRYSTALLOGRAPHICA SECTION C, Issue 9 2009Ricaurte Rodríguez Molecules of the title compound, C16H13N5O2, have no internal symmetry despite the symmetric pattern of substitution in the pyrimidine ring. The intramolecular distances indicate polarization of the electronic structure. There are two intramolecular N,H...O hydrogen bonds and molecules are linked into centrosymmetric dimers by pairs of three-centre C,H...(O)2 hydrogen bonds. These dimers are linked into chains by means of a ,,, stacking interaction. [source] Hydrogen-bonded supramolecular motifs in 2-amino-4,6-dimethoxypyrimidinium picrate and pyrimethaminium picrate dimethyl sulfoxide solvateACTA CRYSTALLOGRAPHICA SECTION C, Issue 2 2009Kaliyaperumal Thanigaimani In the crystal structures of 2-amino-4,6-dimethoxypyrimidinium 2,4,6-trinitrophenolate (picrate), C6H10N3O2+·C6H2N3O7,, (I), and 2,4-diamino-5-(4-chlorophenyl)-6-ethylpyrimidin-1-ium (pyrimethaminium or PMN) picrate dimethyl sulfoxide solvate, C12H14ClN4+·C6H2N3O7,·C2H6OS, (II), the 2-amino-4,6-dimethoxypyrimidine and PMN cations are protonated at one of the pyrimidine N atoms. The picrate anion interacts with the protonated cations through bifurcated N,H...O hydrogen bonds, forming R21(6) and R12(6) ring motifs. In (I), Z, = 2. In (II), two inversion-related PMN cations are connected through a pair of N,H...N hydrogen bonds involving the 4-amino group and the uncharged N atom of the pyrimidine ring, forming a cyclic hydrogen-bonded R22(8) motif. In addition to the pairing, the O atom of the dimethyl sulfoxide solvent molecule bridges the 2-amino and 4-amino groups on both sides of the paired bases, resulting in a self-complementary ,DADA, array of quadruple hydrogen-bonding patterns. [source] 2- tert -Butyloxymethyl-6-cyano-2,3-dihydro-5H -oxazolo[3,2- a]pyrimidin-5-oneACTA CRYSTALLOGRAPHICA SECTION C, Issue 1 2000Corinne Chaimbault The condensation reaction of 2-amino-5- tert -butyloxymethyl-2-oxazoline with ethyl cyano(ethoxymethylene)acetate led to the title cycloadduct. The structure indicates a delocalization in the pyrimidine ring. [source] Active-site changes in the pyruvate dehydrogenase multienzyme complex E1 apoenzyme component from Escherichia coli observed at 2.32,Å resolutionACTA CRYSTALLOGRAPHICA SECTION D, Issue 11 2006Palaniappa Arjunan The first enzymatic component, E1 (EC 1.2.4.1), of the pyruvate dehydrogenase multienzyme complex (PDHc) utilizes thiamine diphosphate (ThDP) and Mg2+ as cofactors. The structure of a branched-chain-specific E1 apoenzyme from the heterotetrameric ,2,2 E1 family was recently reported and showed that disorder-to-order transformations in two active-site loops take place upon cofactor binding. To ascertain what effect the absence of cofactor may have in the homodimeric ,2Escherichia coli PDHc E1, the corresponding apoenzyme has been prepared and its three-dimensional structure determined and analyzed at 2.32,Å by crystallographic methods. This represents the first reported apoenzyme structure for any E1 component from the homodimeric ,2 family. Electron-density features occurring in the region where the cofactor pyrimidine ring would normally be expected to bind are of size, shape and location compatible with water molecules that form a hydrogen-bonded linkage between residues Glu571 and Val192, which normally make conserved interactions with the ThDP cofactor. A histidine side chain that normally forms hydrogen bonds to ThDP is disordered in its absence and partially occupies two sites. Unlike in the reported heterotetrameric branched-chain apo-E1, no disorder/order loop transformations are evident in apo-PDHc E1 relative to the holo-E1 enzyme (PDHc E1,ThDP,Mg2+). Differences in the extent of hydrogen-bonding networks found in the apo-E1 enzyme, the holo-E1 enzyme and in an inhibitor complex with bound thiamine 2-thiazolone diphosphate (ThTDP), PDHc E1,ThTDP,Mg2+, are described. [source] Structure of bovine pancreatic ribonuclease complexed with uridine 5,-monophosphate at 1.60,Å resolutionACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 2 2010Steven B. Larson Bovine pancreatic ribonuclease A (RNase A) was crystallized from a mixture of small molecules containing basic fuchsin, tobramycin and uridine 5,-monophosphate (U5P). Solution of the crystal structure revealed that the enzyme was selectively bound to U5P, with the pyrimidine ring of U5P residing in the pyrimidine-binding site at Thr45. The structure was refined to an R factor of 0.197 and an Rfree of 0.253. [source] The Z isomer of 2,4-diaminofuro[2,3- d]pyrimidine antifolate promotes unusual crystal packing in a human dihydrofolate reductase ternary complexACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 8 2009Vivian Cody The crystal structure of the ternary complex of human dihydrofolate reductase (hDHFR) with NADPH and the Z isomer of 2,4-diamino-5-[2-(2,-methoxyphenyl)propenyl]-furo[2,3- d]pyrimidine (Z1) shows that the Z isomer binds in the normal antifolate orientation in which the furo oxygen occupies the 8-amino position observed in the binding of 2,4-diaminopteridine antifolates such as methotrexate and with the methoxyphenyl moiety cis to and coplanar with the furo[2,3- d]pyrimidine ring. The hDHFR ternary complex crystallized in the orthorhombic space group P212121 and its structure was refined to 1.7,Å resolution. Although other hDHFR complexes crystallize in this space group, these data provide only the second example of an unusual packing arrangement in which the conserved active-site Arg70 forms a salt bridge to the side chain of Glu44 from a symmetry-related molecule. As a result, the conformations of Phe31 and Gln35 shift with respect to those observed in the structure of mouse DHFR bound to Z1, which crystallizes in the monoclinic space group P21 and shows that Gln35 interacts with Arg70. [source] Species differences in enantioselective 2-oxidations of RS-8359, a selective and reversible MAO-A inhibitor, and cinchona alkaloids by aldehyde oxidaseBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 3 2006Kunio Itoh Abstract The 2-oxidation activity on the pyrimidine ring of RS-8359, a MAO-A inhibitor, is the major metabolic pathway catalysed by aldehyde oxidase. This study investigated the species differences in the 2-oxidation activity by using liver cytosolic fractions from rats, mice, guinea-pigs, rabbits, dogs, monkeys and humans. The Vmax/Km value for the (S)-enantiomer of RS-8359 was extremely high in monkeys and humans, moderate in guinea-pigs, and low in rats and mice. Dogs were deficient in 2-oxidation activity. The (R)-enantiomer was only oxidized at a very low rate in guinea-pigs, monkeys and humans, and not oxidized in rats, mice and rabbits. Thus, marked species differences and enantioselectivity were obvious for the 2-oxidation of the (S)-enantiomer of RS-8359. The in vitro results were in good accordance with previously reported in vivo excretion data of the 2-keto metabolite and the non-detectable plasma concentrations of the (S)-enantiomer in monkeys and humans after administration of racemic RS-8359. Enantioselectivity was also observed for the oxidation of cinchona alkaloids catalysed by aldehyde oxidase. Among the four cinchona alkaloids studied, the oxidation activity of cinchonidine, which has no substituents at the 6-hydroxy group but bears (8S,9R)-configurations, was highest. As opposed to the (S)-enantiomer, an extremely high catalytic activity of cinchonidine was confirmed in rabbits, but not in monkeys or humans. Rabbit liver aldehyde oxidase was suggested to have characteristic properties around the active site. Copyright © 2006 John Wiley & Sons, Ltd. [source] Interaction of Cytidine 5,-Monophosphate with Au(111): An In Situ Infrared Spectroscopic StudyCHEMPHYSCHEM, Issue 9-10 2009Thomas Doneux Dr. Abstract Attracted to gold: The interaction of cytidine 5,-monophosphate (CMP) with gold surfaces is studied at the Au(111) | aqueous solution interface. In situ infrared spectroscopy studies show that cytidine 5,-monophosphate is chemisorbed on Au(111) through the N3 atom of the pyrimidine ring (see picture). The interaction of cytidine 5,-monophosphate (CMP) with gold surfaces is studied by means of in situ infrared spectroscopy and cyclic voltammetry at the Au(111) | aqueous solution interface. Similar to other nucleic acid components, cytidine 5,-monophosphate is chemisorbed on the surface at positive potentials, and the amount of adsorbed CMP increases with the potential. Subtractively normalized interfacial Fourier-transform infrared spectroscopy (SNIFTIRS) is used to identify the adsorbed and desorbed species. Upon electrochemical desorption, the molecules released in solution are unprotonated on the N3 atom. Striking similarities are found between the spectrum of adsorbed CMP and the solution spectrum of protonated CMP. The origin of such similarities is discussed. The results strongly suggest that chemisorption occurs through the N3 atom of the pyrimidine ring. A comparison is drawn with cytidine, whose electrochemical and spectroscopic behaviors are also investigated. [source] A Combined Experimental and Theoretical Study of Anion,, Interactions in Bis(pyrimidine) SaltsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 35 2007Angel Garcia-Raso Abstract We report the synthesis and X-ray characterization of an N,N, -tetramethylenebis(2-aminopyrimidinium) tetrafluoroborate salt that exhibits anion,, interactions that are responsible for the crystal packing. The anion forms a sandwich complex with two pyrimidine rings. When the anion is nitrate, the crystal packing is governed by anion,, interactions and hydrogen bonds, and the sandwich complex is not formed. Finally, a theoretical study of the anion,, interactions in charged pyrimidine rings is in good agreement with the experimental findings. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] 2-Amino-4-chloro-5-formyl-6-[methyl(2-methylphenyl)amino]pyrimidine and 2-amino-4-chloro-5-formyl-6-[(2-methoxyphenyl)methylamino]pyrimidine are isostructural and form hydrogen-bonded sheets of R22(8) and R66(32) ringsACTA CRYSTALLOGRAPHICA SECTION C, Issue 1 2009Jorge Trilleras 2-Amino-4-chloro-5-formyl-6-[methyl(2-methylphenyl)amino]pyrimidine, C13H13ClN4O, (I), and 2-amino-4-chloro-5-formyl-6-[(2-methoxyphenyl)methylamino]pyrimidine, C13H13ClN4O2, (II), are isostructural and essentially isomorphous. Although the pyrimidine rings in each compound are planar, the ring-substituent atoms show significant displacements from this plane, and the bond distances provide evidence for polarization of the electronic structures. In each compound, a combination of N,H...N and N,H...O hydrogen bonds links the molecules into sheets built from centrosymmetric R22(8) and R66(32) rings. The significance of this study lies in its observation of the isostructural nature of (I) and (II), and in the comparison of their crystal and molecular structures with those of analogous compounds. [source] Hydrogen-bonded sheet structures in neutral, anionic and hydrated 6-amino-2-(morpholin-4-yl)-5-nitrosopyrimidinesACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2008Fabían Orozco In each of 6-amino-3-methyl-2-(morpholin-4-yl)-5-nitrosopyrimidin-4(3H)-one, C9H13N5O3, (I), morpholin-4-ium 4-amino-2-(morpholin-4-yl)-5-nitroso-6-oxo-1,6-dihydropyrimidin-1-ide, C4H10NO+·C8H10N5O3,, (II), and 6-amino-2-(morpholin-4-yl)-5-nitrosopyrimidin-4(3H)-one hemihydrate, C8H11N5O3·0.5H2O, (III), the bond distances within the pyrimidine components are consistent with significant electronic polarization, which is most marked in (II) and least marked in (I). Despite the high level of substitution, the pyrimidine rings are all effectively planar, and in each of the pyrimidine components, there are intramolecular N,H...O hydrogen bonds. In each compound, the organic components are linked by multiple N,H...O hydrogen bonds to form sheets of widely differing construction, and in compound (III) adjacent sheets are linked by the water molecules, so forming a three-dimensional hydrogen-bonded framework. This study also contains the first direct geometric comparison between the electronic polarization in a neutral aminonitrosopyrimidine and that in its ring-deprotonated conjugate anion in a metal-free environment. [source] | |||||||||||||||||||||||||