Synthetic Adrenaline Receptors Based on Bisphosphonates

Synthetic models of the natural adrenergic receptors are presented, and their binding properties to several biologically important amines and amino alcohols in dimethylsulfoxide and methanol are discussed. NMR titrations have been carried out to determine their binding constants.     

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.     

Stereochemical dependence of NMR geminal spin-spin coupling constants

In this work it was sought to explore the versatility of geminal spin-spin coupling constants, (2)J(XY) SSCCs, as probes for stereochemical studies. A set of compounds, where their experimental (2)J(XY) SSCCs through the X-C-Y molecular fragment are predicted to be sensitive to hyperconjugative interactions involving either bonding or antibonding orbitals containing the C carbon atom ('coupling pathway'), were analyzed. SSCC calculations were performed for some selected examples using the second order polarization propagator approximation (SOPPA) method or within the DFT-B3LYP framework. Hyperconjugative interactions were calculated within the Natural Bond Orbital (NBO) approach. Results are condensed in two qualitative rules: Rule I(M)-hyperconjugative interactions transferring charge into the coupling pathway yield a positive increase to the Fermi contact (FC), contribution to (2)K(XY) reduced spin-spin coupling constants (RSSCC), and Rule II(M)-hyperconjugative interactions transferring charge from the coupling pathway yield a negative increase to the FC contribution to (2)K(XY) RSSCC.     

Polyoxomolybdate Bisphosphonate Heterometallic Complexes: Synthesis,Structure, and Activity on a Breast Cancer Cell Line

Six polyoxometalates containing Mn^II, Mn^III, or Fe^III as the heteroelement were synthesized in water by treating Mo^VI precursors with biologically active bisphosphonates (alendronate (Ale), zoledronate (Zol), an n‐alkyl bisphosphonate (BPC₉), an aminoalkyl bisphosphonate (BPC₈NH₂)) in the presence of additional metal ions. The Pt complex was synthesized from a polyoxomolybdate bisphosphonate precursor with Mo^VI ions linked by the 2‐pyridyl analogue of alendronate (AlePy). The complexes Mo₄Ale₂Mn, Mo₄Zol₂Mn, Mo₄Ale₂Fe, Mo₄Zol₂Fe, Mo₄(BPC₈NH₂)₂Fe, and Mo₄(BPC₉)₂Fe contain two dinuclear Mo^VI cores bound to a central heterometallic ion. The oxidation state of manganese was determined by magnetic measurements. Complexes Mo₁₂(AlePy)₄ and Mo₁₂(AlePy)₄Pt₄ were studied by solid‐state NMR spectroscopy and the photochromic properties were investigated in the solid state; both methods confirmed the complexation of Pt. Activity against the human breast adenocarcinoma cell line MCF‐7 was determined and the most potent compound was Mn^III‐containing Mo₄Zol₂Mn (IC₅₀≈1.3 μM ). Unlike results obtained with vanadium‐containing polyoxometalate bisphosphonates, cell growth inhibition was rescued by the addition of geranylgeraniol, which reverses the effects of bisphosphonates on isoprenoid biosynthesis/protein prenylation. The results indicate an important role for both the heterometallic element and the bisphosphonate ligand in the mechanism of action of the most active compounds.     

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.     

An Efficient Synthesis of [1,2,4]Triazolo[3,2-d][1,5]benzoxazepin-2-thiones, a Kind of Novel Tricyclic O,N-Heterocycles

A series of novel tricyclic O,N-heterocycles, [1,2,4]triazolo[3,2-d][1,5]benzoxazepin-2-thiones 7 were achieved via acid-induced ring closure of the geminal arylazo isothiocyanate compounds 5 which were derived from substituted chroman-4-ones, followed by feasible ring expansion with simultaneous insertion of the nitrogen atom into the carbon skeleton. The X-ray crystal structure of 7d was also described.     

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.     

On the unusual 2J(C2-H(f)) coupling dependence on syn/anti CHO conformation in 5-X-furan-2-carboxaldehydes

A remarkable difference for (2)J(C(2)-H(f)) coupling constant in syn and anti conformers of 5-X-furan-2-carboxaldehydes (X = CH(3), Ph, NO(2), Br) and a rationalization of this difference are reported. On the basis of the current knowledge of the Fermi-contact term transmission, a rather unusual dual-coupling pathway in the syn conformer is presented. The additional coupling pathway resembles somewhat that of the J(H-H) in homoallylic couplings, which are transmitted by hyperconjugative interactions involving the pi(C=C) electronic system. The homoallylic coupling pathway can be labeled as sigma*(C-H) <-- pi(C=C) --> sigma*(C-H). In the present case, this additional coupling pathway, using an analogous notation, can be labeled as sigma*(C(2)-C(C)) <-- LP(1)(O(1))...LP(2)(O(C)) --> sigma*(C(C)-H(f)) (sigma*(C(2)-C(C))) where O(1) and O(C) stand for the ring and carbonyl O atoms, respectively. This additional coupling pathway is not activated in the anti conformers since both oxygen lone pairs do not overlap.