Now showing items 1-20 of 42

    • 3-(Triphenylphosphoranylidene)-pentane-2,4-dione and diethyl 2-(triphenylphosphoranylidene)-malonate 

      Castañeda Magliona, Fernando; Aliaga Silva, Christian Marcelo; Bunton, Clifford A.; Garland, María Teresa; Baggio, Ricardo (BLACKWELL PUBLISHING, 2005-08)
      The title ylides, 3-(triphenylphosphoranylidene) pentane-2,4-dione, C23H21O2P, (I), and diethyl 2-(triphenylphosphoranylidene)malonate, C25H25O4P, (II), differ in the conformations adopted by their extended ylide moieties. ...
    • A common conformation of stabilized triphenyl phosphonium ylidic diesters with bulky alkoxy groups 

      Castañeda, Fernando; Silva, Paul; Garland, María Teresa; Shirazi, Ata; Bunton, Clifford A. (2009)
      The phosphonium ylidic diesters, methyl and ethyl isopropyl and, methyl and ethyl t-butyl triphenylphosphoranylidene malonates, 1a,b and 2a,b, respectively, have the syn-anti conformation in solution, as in the crystal, ...
    • Aromatic nucleophilic substitution in nucleophilic surfactants. Comparison with alkoxide reactions 

      Bunton, Clifford A.; Díaz, Simon (1976)
      The reactions of 2,4-dinitrochloro- and fluorobenzene (DNC and DNF) with the alkoxide ions of choline, propargyl alcohol, and 2,2,2-trifluoroethanol give ether intermediates which react readily with hydroxide ion. The ...
    • Charge transfer circular dichroism of complexes of copper(II) with aminoacids and heterocyclic ligands 

      Bunel Torrealba, Sergio; Ibarra, Carmen; Bunton, Clifford A. (Pergamon Press, 1975)
      In the u.v. region the C.D. spectra of mixed complexes of Cu(II), aminoacids and heterocyclic ligands depend upon the nature of the heterocyclic ligand, and work on the Cotton effects of bis-Ł-aminoacidates of cu(II) in ...
    • Comparison of conformations of diesters of stabilized phosphonium ylides in solution and in the crystal 

      Castañeda, Fernando; Silva, Paul; Garland, María Teresa; Shirazi, Ata; Bunton, Clifford A. (2009)
      Computed bond lengths and angles of methyl ethyl and dimethyl triphenyl phosphonium ylidic diesters, 1b, c, respectively, are similar to those in the crystal, as for the diethyl ester, 1a, where both acyl oxygens are anti ...
    • Complexation of amino sugars with cobalt(III) bis (phenanthroline) 

      Bunel Torrealba, Sergio; Ibarra, Carmen; Moraga, Exequiel; Parada Aliste, José; Blasko, Andrei; Whiddon, Christy; Bunton, Clifford A. (Elsevier, 1998)
      The I3- salts soluble in acetone and sparingly so in methanol, and I3- inhibits formation of Co(II) so that minor decomposition of acomplex does not broaden its 1H NMR signals. The (phen)2 complex of Co(III) with D-glucosamine ...
    • Complexation of mannosamine with cobalt(III) bis-phenanthroline. Isolation of a stable triiodide salt 

      Bunel Torrealba, Sergio; Ibarra, Carmen; Moraga, Exequiel; Parada Aliste, José; Blasko, Andrei; Bunton, Clifford A. (Sociedad Chilena de Química, 1997)
      D-β-Mannosamine reacts with cobalt(III) bis-phenanthroline to form a single 1:1 complex with the ∆ configuration at Co(III) which can be isolated as the stable triiodide salt.
    • Complexation of sucrose with cobalt(III)bis(phenanthroline) 

      Parada Aliste, José; Bunel Torrealba, Sergio; Ibarra, Carmen; Larrazábal Rojas, Guillermo; Moraga, Exequiel; Gillitt, N. D.; Bunton, Clifford A. (ELSEVIER SCI LTD, 2000-10-20)
      The Delta-[Co(III)bis(phenanthroline)(sucrose)](3+) complex forms with little perturbation of the sucrose conformation, and complexation by HO-2(g) and HO-1(f).
    • Complexes of bivalent cations with neryl and geranyl pyrophosphate: Their role in terpene biosynthesis 

      Chayet, Liliana; Rojas, M. Cecilia; Cori, Osvaldo; Bunton, Clifford A.; McKenzie, Don C. (1984)
      Kinetic analysis of the nonenzymic solvolysis of neryl and geranyl pyrophosphate (NPP and GPP, respectively) showed that the dissociation constants of the bis-metallic complexes with Mg2+ and Mn2+ were larger for NPP than ...
    • Complexes of Co(III) with L-sorbose and phenanthroline 

      Blasko, Andrei; Bunton, Clifford A.; Moraga, Exequiel; Bunel Torrealba, Sergio; Ibarra, Carmen (ELSEVIER SCIENCE BV, 1995-12-20)
      L-Sorbose and two molecules of 1,10-phenanthroline form a complex with Co(III) which has the Lambda configuration about Co(III), based on CD and ORD spectra, The H-1 NMR signals of alpha-L-sorbopyranose and its mixed ...
    • COMPLEXES OF COBALT(III) WITH D-FRUCTOSE AND PHENANTHROLINE 

      Moraga, Exequiel; Bunel Torrealba, Sergio; Ibarra, Carmen; Blasko, Andrei; Bunton, Clifford A. (ELSEVIER SCIENCE BV, 1995-03-01)
      D-Fructose and 1,10-phenanthroline form complexes with Co(III). Configurations about Co(III) are assigned from the CD and ORD spectra of the separated Lambda and Delta diastereomers, and Lambda strongly predominates in the ...
    • COMPLEXES OF COBALT(III) WITH D-GLUCOSAMINE AND AMINES 

      Bunel Torrealba, Sergio; Ibarra, Carmen; Moraga, Exequiel; Calvo Pérez, Víctor; Blasko, Andrei; Bunton, Clifford A. (ELSEVIER SCIENCE BV, 1993-02-01)
      D-Glucosamine and ammonia, 1,2-ethylenediamine, or 1,10-phenanthroline form complexes with Co(III)*. The complexes are: [Co(NH3)3-H2O-D-glucosamine]3+, [Co(en)2.D-glucosamine]2+ and [Co(phen)2.D-glucosamine]3+. Formation ...
    • Conformational analysis of 3-triphenylphosphoranylidene-2,4-pentanedione by NMR spectroscopy and geometrical optimization 

      Castañeda Magliona, Fernando; Recabarren Gajardo, Gonzalo Iván; Hu, J.; Gillitt, N. D.; Bunton, Clifford A. (TAYLOR & FRANCIS LTD, 2003-11)
      The diacyl ylide, 3-triphenylphosphoranylidene-2,4-pentanedione (2) can adopt conformations stabilized by ylidic resonance with both acyl oxygens syn- or with one oxygen syn- and the other anti- to cationoid phosphorus, ...
    • Conformational differences in stabilized diketo and diester phosphonium ylides in a solid and in solution 

      Castañeda Magliona, Fernando; Aliaga Silva, Christian Marcelo; Garland, María Teresa; Hu, J.; Gillitt, N. D.; Bunton, Clifford A. (TAYLOR & FRANCIS LTD, 2007-01)
      The diacyl ylid, 3-triphenylphosphoranylidene-2,4-pentanedione 2 can adopt conformations with one oxygen syn- and the other anti- to phosphorus 2a as in the crystal, or with both oxygens syn- to phosphorus 2b. In solution, ...
    • Conformations of monoylidic diester triphenylphosphonium ylides 

      Castañeda Magliona, Fernando; Silva, Paul; Acuña, Cristina; Garland, María Teresa; Bunton, Clifford A. (2013)
      In ylidic triphenylphosphonium carboxylic esters the ester oxygen can be oriented towards (syn) or away (anti) from phosphorus, but except for small ylidic ester groups, e.g., Me, the anti conformer is dominant. With ...
    • Conformer determination of stabilized triphenyl phosphonium acyl ylides by infrared spectroscopy 

      Bunton, Clifford A.; Silva, Paul; Castañeda, Fernando (2009)
      Stretching frequencies of acyl groups of stabilized triphenyl phosphonium ylides with ester, keto or cyano groups depend in part on the orientations of the acyl groups, syn or anti, with respect to phosphorus. Frequencies ...
    • Cyano triphenyl phosphonium ylides stabilized by ester or keto groups: Computed conformations and crystal structures 

      Castañeda Magliona, Fernando; Acuña, C.; Garland, María Teresa; Gillitt, N. D.; Shirazi, A.; Yunes, S. J.; Bunton, Clifford A. (TAYLOR & FRANCIS LTD, 2007)
      The mixed stabilized triphenyl phosphonium ylides Ph3P= C(CN)CO-R and Ph3P= C(CN)COOR, R= CH3, C2H5, CH(CH3)(2), 1a, c and 2a, b, respectively, have sharp H-1 and C-13 NMR signals, except for 2b in some conditions. Ab ...
    • Cyano-stabilized triphenylphosphonium ylids 

      Castañeda Magliona, Fernando; Bunton, Clifford A.; Baggio, Ricardo; Garland, María Teresa (BLACKWELL PUBLISHING, 2007-01)
      Crystalline cyano-stabilized triphenylphosphonium ylids with keto or ester groups give rise to an extended electronic delocalization. In methyl 2-cyano-2-(trimethylphosphonio)-ethenoate, Ph3P=C(CN)CO2CH3 or C22H18NO2P, ...
    • Determination of acid dissociation constants of anomers of amino sugars by 1H NMR spectroscopy 

      Blasko, Andrei; Bunton, Clifford A.; Bunel Torrealba, Sergio; Ibarra, Carmen; Moraga, Exequiel (Elsevier Science Publishers B. V., 1997)
      Acid dissociation constants of α- and β-D-glucos-, mannos-, and galactos-ammonium ions have been determined from 1H NMR chemical shifts of the individual anomers in D2O. Values of pKa(D) for the α- and β-ammonium ions ...
    • Differences in the crystal structures of two dialkyl diester triphenyl-phospho-nium ylids 

      Castãeda, Fernando; Jullian Matthaei, Carolina; Bunton, Clifford A.; Garland, María Teresa; Baggio, Ricardo (2007)
      Hydrogen bonding and crystal packing play major roles in determining the conformations of ethyl methyl 2-(triphenyl-phospho-ranyl-idene)malonate, Ph3P=C(CO2CH3)CO2CH2CH3 or C24H23O4P, (I), and dimethyl 2-(triphenyl-phosphor- ...