Influence of Zinc Ions on the Geminal and Bimolecular Stages of the Horse-Myoglobin Oxygenation

The kinetics of nanosecond geminal recombination and bimolar association of molecular oxygen with the horse-heart myoglobin has been investigated by laser flash photolysis. The influence of Zn(II) ions on the dioxygenation and rebonding of myoglobin to a ligand has been considered. The kinetics of the geminal recombination was analyzed within the framework of the model of four states with a side path of ligand motion in the protein matrix. It is shown that an increase in the affinity of myoglobin to O₂ in the presence of Zn(II) ions is predominantly caused by an increase in the rate constant of recombination of molecular oxygen from the primary intraprotein site. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 5, pp. 670–677, September–October, 2005.     

Electron-excessive systems: Study of the character of spectral phenomena of weak magnetic fields and conformations of acetylenic amidoglycols

The synthesis was carried out of model acetylenic amidoglycols. Conclusions were made from an analysis of the PMR spectra on the possibility of transfer of magnetic fields through an electron-excessive acetylenic bond and on conformation of amidoglycols. The low value of the observed nonequivalency of the geminal methyl groups, separated from the asymmetric center by an acetylenic bond, in the PMR spectra is explained by characteristic features of the electronic structure and conformational rigidity of the acetylenic bond.V. I. Nikitin Institute of Chemistry, Academy of Sciences of the Republic of Tadzhikistan, 734063 Dushanbe. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 9, pp. 2097–2103, September, 1992.     

Characterization of industrial alkylpolyphosphonates by infusion electrospray ionization-ion trap mass spectrometry with identification of the impurities by tandem capillary zone electrophoresis

Technical grade diethylene-triaminepentakis(methylenephosphonic acid) (I), dihexamethylene-triaminepentakis(methylenephosphonic acid) (II), ethylene-diaminetetrakis(methylenephosphonic acid) (III), hexamethylene-diaminetetrakis(methylenephosphonic acid) (IV), amino-tris(methylenephosphonic acid) (V), hydroxyethyl-aminobis(methylenephosphonic acid) (VI), 1-hydroxyethylidene-1,1-diphosphonic acid (VII), and 2-phosphonobutane-1,2,4-tricarboxylic acid (VIII) were characterized by ion trap mass spectrometry with electrospray ionization (ESI-ITMS). Using the negative ion mode and acid and alkaline media, peak series corresponding to the nominal compounds and to impurities with a lower number of phosphonate groups were distinguished in I-V. Each series was constituted by [M - nH + (n - 1)Na](-) peaks and peaks produced from them by losses of water, H(3)PO(3)(or water plus HPO(2)), and combined losses. For each [M - nH + (n - 1)Na](-) peak, the number of losses coincided with the number of phosphonate groups not bound to sodium ions minus one (the group bearing the charge). Owing to the hydroxyethyl group, the spectrum of VI was dominated by the formation of intermolecular esters, with both losses and gains of water according to [nM - H +/- mH(2)O](-). A series of [M - nH + (n - 1)Na](-) peaks were observed for VII and VIII, showing in the latter case that the carboxylate groups may also form adducts with sodium ions. Losses of water and H(3)PO(3)were observed in VII, whereas losses of water, CO(2), and HPO(3) were seen in VIII. The reaction pathways leading to the production of the observed ions are described. The nominal compounds and the impurities were also separated and identified by capillary electrophoresis with ESI-ITMS detection.     

Mono and Bisphosphonates from Perfluoro Olefins and Polyfunctional Fluoro Ketones. Syntheses,Molecular Structure and Derivatives

Perfluoroalkenyl phosphonates were formed along with Me₃SiF using CF₃CF=CF₂, CF₃CH=CF₂, F₅SCF=CF₂ or F₅SCH=CF₂ and silylated phosphites, (R¹O)₂POSiMe₃ (R¹=Et, SiMe₃). This straightforward method could be extended to perfluorobutadienes CF₂=C(R^F)C(R^F)=CF₂ (R^F F=F, CF₃). The formation of CF₃C(=O)P(=O)(OSiMe₃)₂ and further reactions to yield bisphosphonates will be described. Acetylphosphonates, R²C(=O)P(=O)(OSiMe₃)₂ (R²=CH₃, CF₃) reacted with the ketimine, CH₃C(=NiPr)Ph to give α-hydroxy-γ-imino phosphonates. Trifluoroacetylphenol and 2,6-bis(trifluoracetyl)-4-methyl-phenol have been proven to be versatile precursors for α-and γ-hydroxy phosphonates. Intermediates in these reactions were found to be cyclic λ⁵σ⁵P species.     

Selective C−C Coupling of Vinyl Epoxides with Diborylmethide Lithium Salts

Vinyl epoxides and styrene oxide can react with diborylmethide lithium salts through an exclusive S_N2 borylmethylation/ring opening in a regio- and diastereoselective way, depending on the nature of the substrate. The ring-opening protocol provides homoallylboronates that can be transformed into challenging diastereomeric bishomoallylic alicyclic 1,3-diols. Unprecedented 3-borylated 1,2-oxaborolan-2-ol products were prepared by borylmethylation/ring opening of 2-methyl-2-vinyloxirane followed by intramolecular cyclization.     

A 1H, 13C, 31P and 15N NMR study of (pyrrolidine-2,2-diyl)bisphosphonic acid,tetraalkyl(pyrrolidine-2,2-diyl)bisphosphonates and acyclic tetraethyl bisphosphonates

A multinuclear magnetic resonance study (¹H, ¹³C, ³¹P, ¹⁵N) was performed on a series of new cyclic pyrrolidine bisphosphonates and acyclic bisphosphonates. Values are reported and discussed for the chemical shifts and coupling constants of the various nuclei. Copyright © 2000 John Wiley & Sons, Ltd.     

Novel Procedure for the Synthesis of 1‐Hydroxy‐1,1‐bisphosphonic Acids using Phenols as Medium

A facile synthetic route for the synthesis of bisphosphonates in phenols is described. Preparations of some of bisphosphonates, which are presently in clinical use such as risedronic acid and alendronate sodium, are synthesized following this new, simple method. This procedure can be useful for the synthesis of this class of bone‐resorptive inhibitors in bulk quantities.