50,827 research outputs found
Metal complexes of cimetidine. Synthesis, X-ray structure determination and semiempirical calculations on the [cimetidinatecopper(II)]+ cation
No full textThe addition of a methanolic solution of cimetidine (1) to a methanolic solution of M2+ cations (M = Co, NJ, Cu, Zn) affords the cationic complexes [M(1)2]2+. In the case of M = Cu the addition of KOH in the reaction medium at 60 °C gives the [Cu(2′)]+ cation, where 2′ is an anionic ligand resulting from deprotonation of a cimetidine molecule modified by methanolic solvolysis of the nitrilic function. The X-ray structure characterization of [Cu(2′)]X·0.5H2O has been performed for X = ClO4- (5) and I- (6). Compound 5 is monoclinic, space group C2/c with a=20.732(8), b=7.471(3), c=23.734(5) Å, β 100.76(3)°, Z=8, R=0.034, Rw=0.045 for 1767 reflections with I>3σ(I). Compound 6 is monoclinic, space group C2/c with a=20.736(3), b=7.426(3), c=22.786(2) Å, β=99.65(1)°, Z=8, R=0.029, Rw=0.045 for 2498 reflections with I>3σ(I). In both compounds the 2′ anion acts as a tetradentate ligand coiled around the almost square planar metal center. Quantomechanical semiempirical calculations (CNDO/ 2) have been carried out on simple models of 2′, 5 and 6. © 1991
A conformational study of some 3-Methylpiperidines by low-temperature 13C-NMR spectroscopy and molecular mechanics calculations
No full text
An investigation on the interaction between Palladium(II) and L-Citrulline by 1H and 13C NMR spectroscopy and potentiometry
No full textA BASIC program for least-squares estimation of the parameters influencing line shapes in multi-site chemical exchange in nuclear magnetic resonance spectrometry
No full text
Small ring constrained peptidomimetics. Synthesis of epoxy peptidomimetics, inhibitors of cysteine proteases
No full textDifferent dipeptide analogues containing an oxirane ring in the place of the peptidic bond were prepared starting from naturally occurring amino acids. N-Fmoc-amino aldehydes were transformed into the corresponding methoxyvinyl derivatives through a Wittig reaction, and the addition of PhSeCl gave a series of different alpha -phenylselenyl aldehydes. Mukajiama reaction with silylketene acetals gave an intermediate product that was finally transformed into the desired oxiranyl peptidomimetics. Following this strategy we were able to control three new contiguous stereocenters starting from the enantiomerically pure amino acid. The dipeptide analogues could be used in SPPS on a SASRIN resin as the final epoxides were relatively unstable under acidic conditions. Moreover the synthesis of the single dipeptide mimetics was carried out on solid phase to generate a small library of epoxy peptidomimetics. Some of the products prepared in this work resulted as time-dependent reversible inhibitors of cysteine protease
An approach to obtaining an optimal design in the non linear least squares determination of binding parameters in a complex biochemical system
No full textN-(indol-3-ylglyoxilyl) amino acid Derivatives: 1H- and 13C-NMR and semiempirical quantum chemical studies
No full textSmall Ring Constrained Peptidomimeics. Synthesis of Epoxy-Peptidomimetics Inhibitors of Cysteine Proteases
No full text- …
