4 documentos corresponden a la consulta.
Palabras contadas: chiral: 14, compounds: 138
Rouge, P.D. - Brousse, B.N. - Moglioni, A.G. - Cozzi, G.A. - Alvarez-Larena, A. - D'Accorso, N. - Moltrasio, G.Y.
Arkivoc 2005;2005(12):8-21
2005
Temas: Spiro-nitrogenheterocycles - Spiro-sulphur heterocycles - Terpenoids - Thiadiazolines - Thiosemicarbazones
Descripción: Preparation of chiral heterocyclic compounds of the thiadiazoline types, starting from natural α,β-unsaturated and bicyclic terpenones is described. Stereochemical assignment of the compounds synthesized was performed by NMR spectroscopy and X-ray analysis. ©ARKAT.
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Yasmin, S. - Suarez, S. - Doctorovich, F. - Roy, T.G. - Baggio, R.
Acta Crystallogr Sect C Cryst Struct Commun 2013;69(8):862-867
2013
Temas: biologically important compounds - chiral compounds - crystal structure - macrocycles - biologically important compounds - Chiral compounds - Hydrogen-bond donors - Inter molecular hydrogen bondings - Macrocycles - Significant differences
Descripción: The three transition-metal complexes, (meso-5,7,7,12,14,14-hexa methyl-1,4,8,11-tetra azacyclo tetra decane-κ4 N)bis (perchlorato-κO)copper(II), [Cu(ClO4)2(C18H40N4)], (I), (meso-5,7,7,12,14,14-hexa methyl-1,4,8,11-tetra azacyclo tetra decane-κ4 N)bis (nitrato-κO)zinc(II), [Zn(NO3)2(C18H40N4)], (II), and aqua chlorido (meso-5,7,7,12,14,14-hexa methyl-1,4,8,11-tetraazacyclo tetra decane-κ4 N)copper(II) chloride, [CuCl(C18H40N4)(H2O)]Cl, (III), are described. The mol ecules display a very similarly distorted 4+2 octa hedral environment for the cation [located at an inversion centre in (I) and (II)], defined by the macrocycle N4 group in the equatorial sites and two further ligands in trans-axial positions [two O-ClO3 ligands in (I), two O-NO2 ligands in (II) and one chloride and one aqua ligand in (III)]. The most significant difference in mol ecular shape resides in these axial ligands, the effect of which on the intra- and inter molecular hydrogen bonding is discussed. In the case of (I), all strong hydrogen-bond donors are saturated in intra molecular inter actions, while weak inter molecular C - H⋯O contacts result in a three-dimensional network. In (II) and (III), instead, there are N - H and O - H donors left over for inter molecular inter actions, giving rise to the formation of strongly linked but weakly inter acting chains. © 2013 International Union of Crystallography.
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Alkorta, I. - Elguero, J. - Provasi, P.F. - Pagola, G.I. - Ferraro, M.B.
J Chem Phys 2011;135(10)
2011
Temas: Chiral discrimination - Hartree-fock - Homogeneous electric field - Isotropic medium - Lithium cations - Nuclear magnetic shieldings - Nuclear shielding - Chirality - Density functional theory - Enantiomers
Descripción: The set of 1:1 and 2:1 complexes of XOOX′ (X, X′ H, CH 3) with lithium cation has been studied to determine if they are suitable candidates for chiral discrimination in an isotropic medium via nuclear magnetic resonance spectroscopy. Conventional nuclear magnetic resonance is unable to distinguish between enantiomers in the absence of a chiral solvent. The criterion for experimental detection is valuated by the isotropic part of nuclear shielding polarisability tensors, related to a pseudoscalar of opposite sign for two enantiomers. The study includes calculations at coupled Hartree-Fock and density functional theory schemes for 17O nucleus in each compound. Additional calculations for 1H are also included for some compounds. A huge static homogeneous electric field, perpendicular to the magnetic field of the spectromer, as big as ≈1.7 108 V m -1 should be applied to observe a shift of ≈1 ppm for 17O magnetic shielding in the proposed set of complexes. © 2011 American Institute of Physics.
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Brousse, B.N. - Moglioni, A.G. - Alho, M.M. - Álvarez-Larena, Á. - Moltrasio, G.Y. - D'Accorso, N.B.
Arkivoc 2002;2002(10):14-23
2002
Temas: Asymmetric spiro-heterocyclic compounds - Terpenones - Thiadiazolines - Thiosemicarbazones - 1,3,3 trimethyl 2 norcamphanone - camphor - heterocyclic compound - menthone - n [aza(1,7,7 trimethylbicyclo[2.2.1]hept 2 ylidene)methyl]acetamide - terpene derivative
Descripción: Preparation of chiral heterocyclic compounds of the thiadiazoline types, starting from natural terpenones such as fenchone, camphor and menthone, is described. Stereochemical assignment of the compounds synthesized was performed by NMR spectroscopy and X-ray analysis.
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