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Dione
Terms modified by Dione Selected AbstractsNovel Phosphine-Catalyzed Zipper Cyclization of Aliphatic Diyne,Dione and Yne,Dione Systems.CHEMINFORM, Issue 22 2003Hirofumi Kuroda No abstract is available for this article. [source] Benzodiazepine Alkaloids from Marine-Derived Endophytic Fungus Aspergillus ochraceusHELVETICA CHIMICA ACTA, Issue 7 2009Chuan-Ming Cui Abstract A new fungus-derived benzodiazepine analogue, 2-hydroxycircumdatin C (1), and a compound which has been isolated from a natural resource for the first time, but has been previously synthesized, namely (11aS)-2,3-dihydro-7-methoxy-1H -pyrrolo[2,1- c][1,4]benzodiazepine-5,11(10H,11aH)-dione (2), along with five structurally related known alkaloids (3,7), were isolated from Aspergillus ochraceus, an endophytic fungus derived from the marine brown alga Sargassum kjellmanianum. Their structures were established on the basis of spectroscopic methods. The absolute configuration of 1 was determined through CD evidence. Compound 1 displayed significant DPPH radical-scavenging activity with an IC50 value of 9.9,,M, which is 8.9-fold more potent than that of butylated hydroxytoluene (BHT), a well-known synthetic positive control. [source] Synthesis, DNA-Binding and Photocleavage Studies of the Ruthenium(II) Complexes [Ru(phen)2(ppd)]2+ and [Ru(phen)(ppd)2]2+ (ppd=Pteridino[6,7- f],[1,10]phenanthroline-11,13(10H,12H)-dione, phen=1,10-Phenanthroline)HELVETICA CHIMICA ACTA, Issue 3 2008Feng Gao Abstract Two new complexes, [Ru(phen)2(ppd)]2+ (1) and [Ru(phen)(ppd)2]2+ (2) (ppd=pteridino[6,7- f],[1,10]phenanthroline-11,13(10H,12H)-dione, phen=1,10-phenanthroline) were synthesized and characterized by ES-MS, 1H-NMR spectroscopy, and elemental analysis. The intercalative DNA-binding properties of 1 and 2 were investigated by absorption-spectroscopy titration, luminescence-spectroscopy studies, thermal denaturation, and viscosity measurements. The theoretical aspects were further discussed by comparative studies of 1 and 2 by means of DFT calculations and molecular-orbital theory. Photoactivated cleavage of pBR322 DNA by the two complexes were also studied, and 2 was found to be a much better photocleavage reagent than 1. The mechanism studies revealed that singlet oxygen and the excited-states redox potentials of the complex may play an important role in the DNA photocleavage. [source] Intercalating Nucleic Acids Containing Insertions of NaphthalimideHELVETICA CHIMICA ACTA, Issue 9 2006Michael Abstract In a study of linker-length dependence, we evaluated naphthalimide (=,1H -benzo[de]isoquinoline-1,3(2H)-dione) and 4-bromonaphthalimide as intercalating nucleic acids. We used a vicinal dihydroxy system when incorporating the six different naphthalimide monomers into DNA, and found the minimum linker-length to be five C-atoms. With this length of the linker, naphthalimide was discriminating between DNA and RNA , stabilizing DNA, while destabilizing RNA. Furthermore, naphthalimide showed universal base character by hybridizing to the four natural bases with a range as narrow as 1.4°. When compared to pyrene, naphthalimide with the same linker-length gave significantly higher thermal meltings when hybridized to DNA. [source] Cycloaddition Reactions of 7-Benzylidenecycloocta-1,3,5-triene with Ethenetetracarbonitrile and 4-Phenyl-3H -1,2,4-triazole-3,5(4H)-dioneHELVETICA CHIMICA ACTA, Issue 7 2005Philip Clements An (E)/(Z) mixture (3,:,2) of 7-benzylidenecycloocta-1,3,5-triene (5) is obtained when 1-benzylcycloocta-1,3,5,7-tetraene (7), prepared by an improved procedure, is treated with t -BuOK in THF. Alternatively, a ca. 9,:,1 mixture (E)/(Z)- 5 can be prepared in a Wittig reaction involving benzaldehyde and cycloocta-2,4,6-trien-1-ylidenetriphenylphoshorane (9). Treatment of (E)/(Z)- 5 88,:,12 with ethenetetracarbonitrile (TCNE) gave a complex mixture of products, from which seven mono-adducts and two bis-adducts were isolated (Sect.,2.2.1). Of the mono-adducts, four are ,4+,2 adducts: two ((E)- and (Z)-isomers) are derived from valence tautomers of the two isomers of (E)/(Z)- 5, while it is tentatively suggested that the other two (again (E)- and (Z)-isomers) are formed from the intermediacy of a pentadienyl zwitterion (Sect.,2.3). The remaining three mono-adducts, two of which are epimers, are ,8+,2 adducts. It is suggested that they are derived from the intermediacy of homotropylium zwitterions (Sect.,2.3). For the two bis-adducts, it is postulated that they are derived from an initial ,2+,2 cycloaddition involving the homotropylium zwitterions followed by ,4+,2 cycloaddition to the valence tautomer of each of the ,2+,2 cycloadducts. With 4-phenyl-3H -1,2,4-triazole-3,5(4H)-dione (6), (E)/(Z)- 5 91,:,9 yielded two ,4+,2 cycloadducts ((E)- and (Z)-isomers) as well as two epimeric ,8+,2 cycloadducts (Sect.,2.2.2). The intermediacy of pentadienyl (tentative suggestion) and homotropylium zwitterions accounts for the formation of the products (Sect.,2.3). [source] Chemical Constituents from the Fruits of Madhuca latifoliaHELVETICA CHIMICA ACTA, Issue 5 2004From the fruit coats of the medicinal plant Madhuca latifolia were isolated three new compounds, the triterpenoid madhucic acid (=3,- (octanoyloxy)-11-oxoolean-12-en-28-oic acid; 1), the untypical isoflavone madhushazone (=9-methoxy-7-(2,3,6-trimethoxyphenyl)-[1,3]dioxolo[4,5- g][1]benzopyran-8(8H)-one; 2), and a bis(isoflavone) named madhusalmone (=5,14-dimethoxy-3,12-bis(3,4,5-trimethoxyphenyl)-1,6,8,10,15,17-hexaoxanaphtho[2,,3,:,6,7]cyclodeca[1,2- b]naphthalene-4,13(4H,13H)-dione; 3), as well as eight known constituents, and their structures were elucidated by spectral analysis, including 2D-NMR techniques. [source] New Long-Chain Esters and Adenine Analogs from the Leaves of Formosan Bridelia balansaeHELVETICA CHIMICA ACTA, Issue 7 2003Yeh-Hsin Tsai Six new compounds, including the two long-chain esters balansenate I (=6,8,11-trimethyldodecanoic acid (2E)-3-methylhexadec-2-enyl ester; 1) and balansenate II (=10,12,15-trimethylhexadedecanoic acid (2E)-3-methylhexadec-2-enyl ester; 2), the eburicane-like triterpenoid bridelone (=hexadecahydro-4,4,10,13,14-pentamethyl-17-(5-methyl-1,4-dimethylenehexyl)-3H -cyclopenta[a]phenanthren-3-one; 3), the ,deimino-xanthine', bridelonine (=5-(3-methylbut-2-enyl)pyrrolo[3,4- d]imidazole-4,6(1H,5H)-dione; 6), and the two adenine analogs 9-(3-methylbut-2-enyl)adenine (7) and 1-(3-methylbut-2-enyl)adenine (8), besides three known compounds, i.e., N6 -(3-methylbut-2-enyl)adenine (4), 3-(3-methylbut-2-enyl)adenine (5), and adenine (9), were isolated from the leaves of Formosan Bridelia balansae. The novel skeleton of 6 consists of a fused pyrrolidine-2,5-dione and imidazole moiety. The already known adenines 7 and 8 were isolated for the first time from a plant. The structures of the isolated compounds were elucidated by spectroscopic analyses. [source] [1.1]Ferrocenophane-1,12-dione as a Precursor of 1,12-Di(cyclopenta-2,4-dienylidene)-[1.1]ferrocenophane, a Doubly Bridged DifulveneADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7-8 2009José Ramon Garabatos-Perera Abstract An improved synthesis of [1.1]ferrocenophane-1,12-dione (2) by oxidation of [1.1]ferrocenophane with 2,3-dichloro-5,6-dicyano- p -benzoquinone (DDQ) is presented. The syn conformer of dione 2 is structurally characterized. The compound undergoes various addition reactions at the bridging carbonyl groups. Attempts to add 1,1,-dilithioferrocene result, however, in the diadduct 9, not in the symmetric trinuclear diol 8. Reaction of 2 with sodium cyclopentadienide in the presence of aluminium trichloride (AlCl3) gives the respective difulvene 11 in excellent yield. The dynamic behavior of 11 is investigated by variable temperature 1H,NMR measurements (VT-NMR). The cyclovoltammogram of 11 indicates two reversible oxidation steps. Reduction of difulvene 11 with lithium aluminium hydride (LiAlH4) results in the formation of [1.1]ferrocenophane 12 with cyclopentadienyl anion substituents at either one of the two bridges. While attempts to generate a third ferrocene moiety by reaction with iron(II) choride (FeCl2) have failed so far, the formation of 12 is established by protonolysis and methylation reactions. [source] Microbial transformation of androst-4-ene-3, 17-dione by Bordetella sp.JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 5 2009B4 CGMCC 222 Abstract BACKGROUND: Microbial transformation of steroids has attracted widespread attention, especially the transformation of those steroids synthesized with difficulty by chemical methods. In this study, microbial transformation of androst-4-ene-3, 17-dione (AD) by Bordetella sp. B4 was investigated, and the effect of temperature on transformation was studied. RESULTS: Three metabolites were purified by preparative TLC and HPLC, and identified as androsta-1,4-diene-3,17-dione (ADD), 9,-hydroxyandrost-4-ene-3, 17-dione (9,-OH-AD), and 3-hydroxy-9, 10-secoandrost-1, 3, 5-triene-9, 17-dione (3-OH-SATD) by nuclear magnetic resonance imaging (NMR), Fourier transform infrared spectroscopy (FTIR) and mass spectroscopy (MS). It was first reported that the genus of Bordetella has the capability of AD degradation. Microbial transformation of AD was performed at 30 °C, 37 °C, 40 °C and 45 °C. The 9,-OH-AD yield reached a maximum within 16 h when the strain was cultivated in media with AD as sole carbon at 37 °C. Surprisingly, ADD was produced by the strain cultivated at 40 °C but not at 37 °C, which was different from previous reports. It was deduced that the alcohol dehydrogenase that catalyzed the transformation of AD to ADD may be temperature sensitive. CONCLUSION: Androst-4-ene-3,17-dione was converted into 9,-hydroxyandrost-4-ene-3, 17-dione and other metabolites rapidly by Bordetella sp. B4. It is anticipated that the strain Bordetella sp. B4 CGMCC 2229 can be used in the steroids industry. Copyright © 2009 Society of Chemical Industry [source] On the purity of 2-[ortho -anilinyl]-1,3-benzoxazole derived from 2H -3,1-benzoxazine-2,4(1H)dione (isatoic anhydride) [1,2],JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 2 2010Karen M. Button The Lewis acid catalyzed synthesis and chromatographic purification of isatoic anhydride-derived 2-(2,-anilinyl)-1,3-benzoxazole (2) can result in the co-isolation of 2 and a light pink colored impurity (<5%). This latter species has been identified (NMR, single crystal X-ray diffraction, mp) as 2,-hydroxy-2-aminobenzanilide (3), which represents a predictable intermediate in the formation of 2. Compound 3 crystallizes in an orthorhombic crystal system of space group P212121 with four molecules in the unit cell (, = , = , = 90°; a = 6.715 (2) Å, b = 12.100 (4) Å, c = 13.321 (4) Å; V = 1082.2 (6) Å3). Pure 2 is characterized as a colorless, high-melting solid; unlike the dark colored oil that is isolated if 2 contains traces of 3. J. Heterocyclic Chem., (2010). [source] Diverse reactivity of ,-carbanions derived from alkylidenephosphoranes toward 2-(1,5 -diazynylidene)-1H -indene-1,3-(2H)dione.JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 6 2008General approach to conjugated oxadiazines, pyridazines, spiro[3]pyrazoles Different types of phosphonium carbanions were applied to 2-diazonio-1,3-dioxo-2,3-dihydro-1H -inden-2-ide (1) in order to synthesize a number of condensed and fused N -heterocycles. When 1 was treated with cyanomethyltriphenylphosphonium chloride oxadiazine-, and pyridazine derivatives were obtained whereas bis-indanylidene derivatives resulted from the reaction of 1 with methyl_ and ethyltriphenylphosphonium bromides. On the other hand, a series of substituted and unsubstituted spiro[3,]pyrazoles were obtained from the di azo substrate when reacted with vinyl_and allyltriphenylphosphonium bromides. [source] Pyrimido[4,5- c]pyridazine-5,7(6H, 8H)-diones: Marvelous substrates for study of nucleophilic substitution of hydrogenJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 3 2005Alexander F. Pozharskii The data on nucleophilic substitution reactions of hydrogen in 6,8-dimethylpyrimido[4,5- c]pyridazine-5,7(6H,8H)-dione, its 3-chloride, N2 -oxide and some other derivatives are reviewed. All these compounds possess a remarkable ability to undergo not only simple functionalizations but also tandem and cascade transformations leading to annelation of various heterocyclic rings. [source] Synthesis of [1,2,5]selena(or thia)diazolo[3,4- e][1,4]diazepines, [1,2,5]selena(or thia)diazolo[3,4- e][1,4]oxazepines and [1,2,5]selena(or thia)diazolo[3,4- c] [1,2,6]thiadiazinesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 5 2000Taisei Ueda Novel heterocycles [1,2,5]selenadiazolo[3,4- e][1,4]diazepines 3a-c, [1,2,5]thiadiazolo[3,4- e]-[1,4]diazepines 7a-c, [1,2,5]selenadiazolo[3,4- e][1,4]oxaepines 4a,b, [1,2,5]thiadiazolo[3,4- e]-[1,4]oxazepines 9a-c and [1,2,5]selena(or thia)diazolo[3,4- c][1,2,6]thiadiazines 10a,b were synthesized starting form 4,6-dimethyl[1,2,5]se]enadiazolo[3,4- d]pyrimidine-5,7(4H,6H)-dione 1 or 4,6-dimethyl-[1,2,5]thiadiazolo[3,4- d]pyrimidine-5,7(4H,6H)-dione 5. [source] Degradable star polymers with high "click" functionalityJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 6 2009James T. Wiltshire Abstract Degradable polyester-based star polymers with a high level of functionality in the arms were synthesized via the "arms first" approach using an acetylene-functional block copolymer macroinitiator. This was achieved by using 2-hydroxyethyl 2,-methyl-2,-bromopropionate to initiate the ring-opening polymerization (ROP) of caprolactone monomer followed by an atom transfer radical polymerization (ATRP) of a protected acetylene monomer, (trimethylsilyl)propargyl methacrylate. The hydroxyl end-group of the resulting block copolymer macroinitiator was subsequently crosslinked under ROP conditions using a bislactone monomer, 4,4,-bioxepanyl-7,7,-dione, to generate a degradable core crosslinked star (CCS) polymer with protected acetylene groups in the corona. The trimethylsilyl-protecting groups were removed to generate a CCS polymer with an average of 1850 pendent acetylene groups located in the outer block segment of the arms. The increased functionality of this CCS polymer was demonstrated by attaching azide-functionalized linear polystyrene via a copper (I)-catalyzed cycloaddition reaction between the azide and acetylene groups. This resulted in a CCS polymer with "brush-like" arm structures, the grafted segment of which could be liberated via hydrolysis of the polyester star structure to generate molecular brushes. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1485,1498, 2009 [source] 1H and 13C NMR assignments and X-ray structures for three monocyclic benzoannelated dilactam polyethersMAGNETIC RESONANCE IN CHEMISTRY, Issue 9 2006Gary L. N. Smith Abstract Three monocyclic polyether dilactams, 17,18-dihydro-5H, 9H -dibenzo[e,n]1,4,10,7,13trioxadiazacyclopentadecine-6,10(7H,11H)-dione (1); 9,10,20,21-tetrahydro-5H, 12H -dibenzo[e,q]1,4,10,13,7,16tetraoxadiazacyclooctadecine-6, 13(7H,14H)-dione (2); and 6,7,9,10-tetrahydro-16H, 20H -dibenzo[h,q]1,4,7,13, 10,16tetraoxadiazacyclooctadecine-17, 21(18H,22H)-dione (3) were isolated during the synthesis of several benzoannelated cryptands. The complete assignments of the 1H and 13C NMR spectra of 1, 2 and 3 in CDCl3 were made using gCOSY, gHMBC, gHMQC, HMQC, HSQC, and NOESY 1D techniques. The ortho (H2) benzene protons show significant downfield shifts (1.16,1.43 ppm) that are consistent with an exodentate orientation for the amide carbonyl groups. The X-ray crystal structures of 1, 2 and 3 show that the carbonyl groups adopt an exodentate conformation in the solid state. Copyright © 2006 John Wiley & Sons, Ltd. [source] Microinjection of glutamate into dorsal motor nucleus of the vagus excites gallbladder motility through NMDA receptor , nitric oxide , cGMP pathwayNEUROGASTROENTEROLOGY & MOTILITY, Issue 3 2004C. Y. Liu Abstract, We have reported that both glutamate and nitric oxide (NO) participated in the regulation of gallbladder motility in dorsal motor nucleus of the vagus (DMV). The aim of this study is to investigate the type of receptor in DMV that mediates the excitatory effect of glutamate on gallbladder motility and the correlation between the glutamate and NO. A frog bladder connected with a force transducer was inserted into the gallbladder to record the change of gallbladder pressure. Glutamate (65 mmol L,1, 100 nL) microinjected into DMV significantly increased the strength of gallbladder phasic contraction. This effect was abolished by ketamine (180 mmol L,1, 100 nL), the specific N -methyl- d -aspartic acid (NMDA) receptor antagonist, but was not influenced by 6-cyaon-7-nitroquinoxaline-2,3-(1H,4H)-dione (CNQX) (180 mmol L,1, 100 nL), the non-NMDA ionotropic receptor antagonist. NG -nitro- l -arginine-emthyl (l -NAME) (1 mol L,1, 100 nL), the nitric oxide synthase (NOS) inhibitor, reversed the excitatory effect of glutamate on gallbladder motility. Microinjection of sodium nitroprusside (SNP), the NO donor, into DMV enhanced the gallbladder motility, and this effect was not modulated by ketamine. Microinjection of NMDA (5 mmol L,1, 100 nL) increased the strength of gallbladder phasic contraction, and this effect was attenuated by methylene blue (100 mmol L,1, 100 nL), the soluble guanylate cyclase inhibitor. These results suggest that glutamate regulate the gallbladder motility through the NMDA receptor , NO , cGMP pathway in DMV. [source] Relationship between urinary profile of the endogenous steroids and postmenopausal women with stress urinary incontinenceNEUROUROLOGY AND URODYNAMICS, Issue 3 2003S.W. Bai Abstract Aims The aims of this study were to investigate whether endogenous steroid hormones are (1) related to pathogenesis of stress urinary incontinence after menopause, (2) are related to severity of stress urinary incontinence, and (3) are related to prognostic parameters of stress urinary incontinence. Methods Twenty post-partum women with clinically diagnosed stress urinary incontinence and 20 age-matched postmenopausal women without stress urinary incontinence (control group) were evaluated. We compared urinary profile of the endogenous steroid hormones patients with stress urinary incontinence and controls, and between grade I and grade II of stress urinary incontinence. We also in vestigated the relationship between urinary profile of the endogenous steroid hormones and prognostic parameters of stress urinary incontinence (maximal urethral closure pressure, functional urethral length, Valsalva leak point pressure, cough leak point pressure, posterior urethrovesical angle, bladder neck descent, and stress urethral axis). The ages of the patients and those in the control group were 64.3,±,5.6 and 57.5,±,3.8 years old and the body mass indexes were 24.96,±,3.14 and 22.11,±, 2.73 kg/m2 in patients and in normal subjects, respectively. Nine patients were grade I and 11 were grade II. Estrone and 17,-estradiol only were detected in all subjects, regardless of control or patient group. It is noteworthy that there were no significant differ ences (P,>,0.05) in the levels of estrone and 17,-estradiol in the urine of postmenopausal normal subjects compared with in the urine of postmenopausal patients with urinary incontinence. E2/E1 ratio was not different between the two groups (P,>,0.05). Among the objective steroids, DHEA, ,4 -dione, ,5 -diol, Te, DHT, 16,-DHT, 11-keto An, THDOC, and THB were not detected either in the urine of normal subjects and nor in the urine of the patients. After comparing androgen levels between normal subjects and patients, no significant differences (P>0.05) were detected, except for 5,-THB and 5,-THF. Neither 5,-THB or 5,-THF were detected in the patients' urine. Et/An (11,-OH Et/11,-OH An) concentration ratios were not significantly different between the two groups, either (P,>,0.05). There were not significant differences of concentrations (,mol/g creatinine) of urinary steroids between grade I and grade II of stress urinary incontinence. Pregnanediol was significantly related to bladder neck descent in supine and sitting positions (R,=,0.79, P,=,0.01, and R,=,0.73, P,=,0.03, respectively), and pregnanetriol was significantly related to maximal urethral closure pressure and functional urethral length (R,=,0.68, P,=,0.04, and R,=,,0.79, P,=,0.01, respectively). Androsterone was significantly related to bladder neck descent in supine and sitting positions (R,=,0.68, P,=,0.04, and R,=,0.78, P,=,0.01, respectively). 5-AT was significantly related to bladder neck descent in sitting position and stress urethral axis (R,=,0.72, P,=,0.03, and R,=,,0.71, P,=,0.03). 11-Keto Et was significantly related to bladder neck descent in supine and sitting positions and related to stress ure thral axis (R,=,0.82, P,=,0.01, and R,=,0.81, P,=,0.01, R,=,,0.67, P,=,0.04, respectively). THS was signi ficantly related to bladder neck descent in supine and sitting positions and related to stress urethral axis (R,=,0.76, P,=,0.02, and R,=,0.74, P,=,0.02, R,=,,0.68, P,=,0.04, respectively). THE was significantly related to bladder neck descent in sitting position (R,=,0.67, P,=,0.04).,-Tetrahydrocortisol/,-tetrahydrocortisol (,-THF/,-THF) and ,-cortol were significantly related to maximal urethral closure pressure and functional urethral length (R,=,0.74, P,=,0.02, and R,=,,0.92, P,=,0.01; R,=,0.71, P,=,0.36, and R,=,,0.87, P,=,0.000, respectively). 17,-Estradiol (E2) was significantly related to bladder neck descent in supine position (R,=,,0.62, P,=,0.04) and 17,-estradiol/estrone (E2/E1) was significantly related to cough leak point pressure (R,=,0.79, P,=,0.01). In conclusion, the urinary concentrations of endogenous steroid metabolites in postmenopausal patients with stress urinary incontinence were not significantly different from normal patients and were not significantly different between grade I and grade II patients with stress urinary incontinence. Some endogenous steroid metabolites were positively or negatively significantly related to prognostic parameters of stress urinary incontinence. Neurourol. Urodynam. 22:198,205, 2003. © 2003 Wiley-Liss, Inc. [source] X-ray crystal structures of diacetates of 6-s- cis and 6-s- trans astaxanthin and of 7,8-didehydroastaxanthin and 7,8,7,,8,-tetradehydroastaxanthin: comparison with free and protein-bound astaxanthinsACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2009Giuditta Bartalucci The crystal structures of the 6-s- cis [s- cis -(1)] and 6-s- trans [s- trans -(1)] conformers of the diacetates of astaxanthin (AXT) and those of (3S,3,S)-7,8-didehydroastaxanthin [(3S,3,S)-3,3,-dihydroxy-7,8-didehydro-,,,-carotene-4,4,-dione (2)] and (3S,3,S)-7,8,7,,8,-tetradehydroastaxanthin [(3S,3,S)-3,3,-dihydroxy-7,8,7,,8,-tetradehydro-,,,-carotene-4, 4,-dione (3)] are reported. The conformations of these four molecules vary in particular with the angle of twist of the end rings out of the plane of the polyene chain; for s- cis -(1), the end rings are twisted out of the plane of the polyene chain by an angle of ,49.0,(5)°, and the conformation is therefore similar to that found for unesterified AXT as well as for the carotenoids, canthaxanthin and ,,,-carotene. For s- trans -(1), the end rings are coplanar with the polyene chain and its conformation is much more similar to that of the protein-bound AXT in the blue protein, crustacyanin, which is found in the shell of lobsters, although s- trans -(1) shows much less bowing of the polyene chain. In (2) and (3) the end rings are also almost coplanar with the polyene chain with the end rings in (2) in the s- cis conformation, and in (3) in the s- trans conformation. Thus, an extensive ensemble of the possible , end-ring conformations has been determined. These structures are compared with one another as well as unbound, unesterified AXT and protein-bound AXT. Also, the effect of the end-ring conformations on the colour and UV,vis spectra of the crystals was established. [source] Two similarly substituted benzo[h]pyrazolo[3,4- b]quinoline-5,6(10H)-diones: supramolecular structures in two and three dimensionsACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2010Yurina Díaz The molecules of 8-methyl-7,10-diphenyl-5H -benzo[h]pyrazolo[3,4- b]quinoline-5,6(10H)-dione, C27H17N3O2, (I), are weakly linked into chains by a single C,H...O hydrogen bond, and these chains are linked into sheets by a ,,, stacking interaction involving pyridyl and aryl rings. In 8-methyl-7-(4-methylphenyl)-10-phenyl-5H -benzo[h]pyrazolo[3,4- b]quinoline-5,6(10H)-dione, C28H19N3O2, (II), the molecules are linked into a three-dimensional framework structure by a combination of C,H...N, C,H...O and C,H...,(arene) hydrogen bonds, together with a ,,, stacking interaction analogous to that in (I). [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] Nonmerohedrally twinned 6-amino-3-methyluracil-5-carbaldehyde: a hydrogen-bonded ribbon containing four types of ringACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2009José M. de la Torre In the title compound [systematic name: 6-amino-5-formyl-3-methylpyrimidine-2,4(1H,3H)-dione], C6H7N3O3, the intramolecular dimensions provide evidence for some polarization of the electronic structure. There is an intramolecular N,H...O hydrogen bond; this and a combination of three intermolecular N,H...O hydrogen bonds generate an almost planar ribbon containing S(6), R22(4), R21(6) and R44(16) rings. These ribbons are linked into sheets by a dipolar carbonyl,carbonyl interaction. The structure was refined as a nonmerohedral twin, with twin fractions 0.7924,(1) and 0.2076,(10). [source] 3-Methyl-7-(2-thienyl)pyrido[2,3- d]pyrimidine-2,4(1H,3H)-dione: ,-stacked bilayers built from N,H...O, C,H...O and C,H..., hydrogen bondsACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2009Jorge Trilleras In the title compound, C12H9N3O2S, the thienyl substituent is disordered over two sets of sites with occupancies of 0.749,(3) and 0.251,(3). A combination of N,H...O, C,H...O and C,H..., hydrogen bonds links the molecules into bilayers and these bilayers are themselves linked into a continuous structure by ,,, stacking interactions. [source] The 2:1 salt-type adduct formed between 6-amino-3-methyl-5-nitrosopyrimidine-2,4(1H,3H)-dione and piperidine: sheets containing 20 independent hydrogen bondsACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2009Fabián Orozco The title compound, piperidinium 6-amino-3-methyl-5-nitroso-2,4-dioxo-1,2,3,4-tetrahydropyrimidin-1-ide 6-amino-3-methyl-5-nitrosopyrimidine-2,4(1H,3H)-dione, C5H12N+·C5H5N4O3,·C5H6N4O3, (I), crystallizes with Z, = 2 in the space group P. There is an intramolecular N,H...O hydrogen bond in each pyrimidine unit and within the selected asymmetric unit the six independent components are linked by 11 hydrogen bonds, seven of the N,H...O type and four of the N,H...N type. These six-component aggregates are linked into sheets by five further hydrogen bonds, three of the N,H...O type and one each of the N,H...N and C,H...O types. [source] Four 7-aryl-substituted pyrido[2,3- d]pyrimidine-2,4(1H,3H)-diones: similar molecular structures but different crystal structuresACTA CRYSTALLOGRAPHICA SECTION C, Issue 4 2009Jorge Trilleras Molecules of 1,3-dimethyl-7-(4-methylphenyl)pyrido[2,3- d]pyrimidine-2,4(1H,3H)-dione, C16H15N3O2, (I), are linked by paired C,H...O hydrogen bonds to form centrosymmetric R22(10) dimers, which are linked into chains by a single ,,, stacking interaction. A single C,H...O hydrogen bond links the molecules of 7-(biphenyl-4-yl)-1,3-dimethylpyrido[2,3- d]pyrimidine-2,4(1H,3H)-dione, C21H17N3O2, (II), into C(10) chains, which are weakly linked into sheets by a ,,, stacking interaction. In 7-(4-fluorophenyl)-3-methylpyrido[2,3- d]pyrimidine-2,4(1H,3H)-dione, C14H10FN3O2, (III), an N,H...O hydrogen bond links the molecules into C(6) chains, which are linked into sheets by a ,,, stacking interaction. The molecules of 7-(4-methoxyphenyl)-3-methylpyrido[2,3- d]pyrimidine-2,4(1H,3H)-dione, C15H13N3O3, (IV), are also linked into C(6) chains by an N,H...O hydrogen bond, but here the chains are linked into sheets by a combination of two independent C,H...,(arene) hydrogen bonds. [source] The influence of sulfur substituents on the molecular geometry and packing of thio derivatives of N -methylphenobarbitalACTA CRYSTALLOGRAPHICA SECTION C, Issue 2 2009Alicja Janik The room-temperature crystal structures of four new thio derivatives of N -methylphenobarbital [systematic name: 5-ethyl-1-methyl-5-phenylpyrimidine-2,4,6(1H,3H,5H)-trione], C13H14N2O3, are compared with the structure of the parent compound. The sulfur substituents in N -methyl-2-thiophenobarbital [5-ethyl-1-methyl-5-phenyl-2-thioxo-1,2-dihydropyrimidine-4,6(3H,5H)-dione], C13H14N2O2S, N -methyl-4-thiophenobarbital [5-ethyl-1-methyl-5-phenyl-4-thioxo-3,4-dihydropyrimidine-2,6(1H,5H)-dione], C13H14N2O2S, and N -methyl-2,4,6-trithiophenobarbital [5-ethyl-1-methyl-5-phenylpyrimidine-2,4,6(1H,3H,5H)-trithione], C13H14N2S3, preserve the heterocyclic ring puckering observed for N -methylphenobarbital (a half-chair conformation), whereas in N -methyl-2,4-dithiophenobarbital [5-ethyl-1-methyl-5-phenyl-2,4-dithioxo-1,2,3,4-tetrahydropyrimidine-6(5H)-one], C13H14N2OS2, significant flattening of the ring was detected. The number and positions of the sulfur substituents influence the packing and hydrogen-bonding patterns of the derivatives. In the cases of the 2-thio, 4-thio and 2,4,6-trithio derivatives, there is a preference for the formation of a ring motif of the R22(8) type, which is also a characteristic of N -methylphenobarbital, whereas a C(6) chain forms in the 2,4-dithio derivative. The preferences for hydrogen-bond formation, which follow the sequence of acceptor position 4 > 2 > 6, confirm the differences in the nucleophilic properties of the C atoms of the heterocyclic ring and are consistent with the course of N -methylphenobarbital thionation reactions. [source] rac -9-Ethyl-12a-hydroxytetradecahydrotriphenylene-1,5(2H,4bH)-dione: stabilization of a new isomer of a functionalized perhydrotriphenylene through a tandem Michael addition,aldol reactionACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2008Luis Arturo García The title compound, C20H30O3, is a new functionalized perhydrotriphenylene derivative formed via a tandem Michael addition,aldol reaction. The structural study reveals that the system of fused rings approximates a C2 point symmetry, with trans,cis,cis ring junctions, while highly symmetric all- trans perhydrotriphenylene, previously characterized, approximates a D3 symmetry. The perhydrotriphenylene nucleus of the title compound corresponds to the third stable stereoisomer isolated for this polycyclic system. Considering that the Cs isomer was obtained recently through a similar tandem reaction, a general strategy is proposed which may help to obtain other stable stereoisomers of perhydrotriphenylene. [source] The 1:1 complex of cytosine and 5-fluorouracil monohydrate revisitedACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2007Gustavo Portalone The monohydrated molecular adduct cytosine,5-fluorouracil,water (1/1/1) (denoted CytFur) [systematic name: 4-aminopyrimidin-2(1H)-one,5-fluoropyrimidine-2,4(1H,3H)-dione,water (1/1/1)], C4H5N3O·C4H3FN2O2·H2O, was determined some 40 years ago [Voet & Rich (1969). J. Am. Chem. Soc.91, 3069,3075] and is widely cited as the first example of an intermolecular complex between two pyrimidinic nucleobases. In view of the importance of these base associations, CytFur has been reinvestigated with modern laboratory equipment to higher precision and with the location and free refinement of the H atoms. The new experiment reaffirms the results of the original and clarifies the tautomeric form exhibited by the compounds. The asymmetric unit comprises a hydrogen-bonded adduct of the canonical amino,oxo tautomers in an exact 1:1 ratio and a water molecule of crystallization. This cyclic dimer forms a layered structure approximately parallel to the bc plane by joining through hydrogen bonds other such cyclic dimers. Disordered water molecules run through tunnels formed by surrounding molecular adducts along the a axis. [source] A fluoresceinophane: 19,4,16-trioxa-1(2,10)-anthracena-2(1,2)-benzenacyclohexadecaphane-17,3(19H)-dioneACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2007Stéphane Dufresne A novel macrocycle containing fluorescein, the highly fluorescent title compound, C31H32O5, has a xanthene core and a benzyl unit that are planar. The latter is rotated by 72.99,(3)° from the xanthene mean plane. The C11 alkyl tether and the xanthene group adopt a cage-like structure and the xanthene adopts a quinoid-type configuration. The compound crystallizes as a racemic mixture with one molecule of each isomer per unit cell. Even though the planes described by the xanthene and the benzene rings of different molecules are separated by 3.341,(4) and 3.73,(1),Å, respectively, there is insufficient overlap between the aryl units to promote ,-stacking. [source] 2,4,6-Triamino-1,3,5-triazine,1H -isoindole-1,3(2H)-dione (1/3)ACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2007Genivaldo Júlio Perpétuo The asymmetric unit of the title compound, C3H6N6·3C8H5NO2, contains a melamine and a phthalimide [1H -isoindole-1,3(2H)-dione] molecule, both residing on a mirror plane, and a second phthalimide molecule residing on a general position. The two components are linked by almost linear N,H...O and N,H...N hydrogen bonds, forming an essentially planar superstructure. These aggregates, related by a twofold screw axis, interact through weak C,H...O contacts, forming chains parallel to the b axis, while those related by translation along the c axis interact via,,, interactions between the , clouds of the aromatic triazine and phthalimide rings to form a stacked structure. [source] 6-Aza-2,-deoxyuridine and N3 -anisoyl-6-aza-2,-deoxyuridineACTA CRYSTALLOGRAPHICA SECTION C, Issue 3 2007Frank Seela In 2-(2-deoxy-,- d - erythro -pentofuranosyl)-1,2,4-triazine-3,5(2H,4H)-dione (6-aza-2,-deoxyuridine), C8H11N3O5, (I), the conformation of the glycosylic bond is between anti and high- anti [, = ,94.0,(3)°], whereas the derivative 2-(2-deoxy-,- d - erythro -pentofuranosyl)- N4 -(2-methoxybenzoyl)-1,2,4-triazine-3,5(2H,4H)-dione (N3 -anisoyl-6-aza-2,-deoxyuridine), C16H17N3O7, (II), displays a high- anti conformation [, = ,86.4,(3)°]. The furanosyl moiety in (I) adopts the S -type sugar pucker (2T3), with P = 188.1,(2)° and ,m = 40.3,(2)°, while the sugar pucker in (II) is N (3T4), with P = 36.1,(3)° and ,m = 33.5,(2)°. The crystal structures of (I) and (II) are stabilized by intermolecular N,H,O and O,H,O interactions. [source] | ||||||||||||||||||||||||||||||||||