Alkene rotation in [Ru(η-C5H5) (L2) (η-alkene][CF3SO3] with L2 = iPr- or pTol-diazabutadiene. X-ray crystal structure of [Ru(η-C5H5(pTol-DAB) (η-ethene][CF3SO3]

Reaction of RuCl(η⁵-C₅H₅(pTol-DAB) with AgOTf (OTf = CF₃SO₃) in CH₂Cl₂ or THF and subsequent addition of L′ (L′ = ethene (a), dimethyl fumarate (b), fumaronitrile (c) or CO (d) led to the ionic complexes [Ru(η⁵-C₅H₅)(pTol-DAB)(L′)][OTf] 2a, 2b and 2d and [Ru(η⁵-C₅H₅)(pTol-DAB)(fumarontrile-N)][OTf] 5c. With the use of resonance Raman spectroscopy, the intense absorption bands of the complexes have been assigned to MLCT transitions to the iPr-DAB ligand. The X-ray structure determination of [Ru(η⁵-C₅H₅)(pTol-DAB)(η²-ethene)][CF₃SO₃] (2a) has been carried out. Crystal data for 2a: monoclinic, space group P2₁/n with A = 10.840(1), b = 16.639(1), C = 14.463(2) Å, β = 109.6(1)°, V = 2465.6(5) ų, Z = 4. Complex 2a has a piano stool structure, with the Cp ring η⁵-bonded, the pTol-DAB ligand σN, σN′ bonded (Ru-N distances 2.052(4) and 2.055(4) Å), and the ethene η²-bonded to the ruthenium center (Ru-C distances 2.217(9) and 2.206(8) Å). The C = C bond of the ethene is almost coplanar with the plane of the Cp ring, and the angle between the plane of the Cp ring and the double of the ethene is 1.8(0.2)°. The reaction of [RuCl(η⁵-C₅H₅)(PPh)₃ with AgOTf and ligands L′ = a and d led to [Ru(η⁵-C₅H₅)(PPh₃)₂(L′)]OTf] (3a) and (3d), respectively. By variable temperature NMR spectroscopy the rottional barrier of ethene (a), dimethyl fumarate (b and fumaronitrile (c) in complexes [Ru(η⁵-C₅H₅)(L₂)(η²-alkene][OTf] with L₂ = iPr-DAB (a, 1b, 1c), pTol-DAB (2a, 2b) and L = PPh₃ (3a) was determined. For 1a, 1b and 2b the barrier is 41.5±0.5, 62±1 and 59±1 kJ mol⁻¹, respectively. The intermediate exchange could not be reached for 1c, and the ΔG^# was estimated to be at least 61 kJ mol⁻. For 2a and 3a the slow exchange could not be reached. The rotational barrier for 2a was estimated to be 40 kJ mol⁻. The rotational barier for methyl propiolate (HC≡CC(O)OCH₃) (k) in complex [Ru(η⁵-C₅H₅)(iPr-DAB) η²-HC≡CC(O)OCH₃)][OTf] (1k) is 45.3±0.2 kJ mol⁻¹. The collected data show that the barrier of rotational of the alkene in complexes 1a, 2a, 1b, 2b and 1c does not correlate with the strength of the metal-alkene interaction in the ground state.     

1-Hydroxy monocyclic carotenoid 3,4-dehydrogenase from a marine bacterium that produces myxol

A crtD (1-HO carotenoid 3,4-dehydrogenase gene) homolog from marine bacterium strain P99-3 included in the gene cluster for the biosynthesis of myxol (3^′,4^′-didehydro-1^′,2^′-dihydro-β,ψ-carotene-3,1^′,2^′-triol) was functionally identified. The P99-3 CrtD was phylogenetically distant from the other CrtDs. A catalytic feature was its high activity for the monocyclic carotenoid conversion: 1^′-HO-torulene (3^′,4^′-didehydro-1^′,2^′-dihydro-β,ψ-caroten-1^′-ol) was prominently formed from 1^′-HO-γ-carotene (1^′,2^′-dihydro-β,ψ-caroten-1^′-ol) in Escherichia coli with P99-3 CrtD, indicating that this enzyme has been highly adapted to myxol biosynthesis. This unique type of crtD is a valuable tool for obtaining 1^′-HO-3^′,4^′-didehydro monocyclic carotenoids in a heterologous carotenoid production system.     

Chemical synthesis of an artificial antigen containing the trisaccharide hapten of Mycobacterium leprae

The crystal and the molecular structure of 4,1′,6′-trichloro-4,1′,6′-trideoxy-galacto-sucrose (TGS) was determined by X-ray analysis at 294 K. Crystals of TGS are orthorhombic, space group P2₁2₁2₁, with a = 7.318(3), b = 12.027(4), c = 18.136(5) Å, V = 1596(1) ų, Z = 4; D_x = 1.655 g.cm^-3, λ(MoK) = 0.71073 Å, μ(MoK) = 5.44 cm^-1, F(000) = 816. The X-ray intensities of 2649 reflections with I 2.5σ(I) were measured with Zr-filtered MoK-radiation. The structure was solved by the Patterson procedure and refined by full-matrix least-squares to a final R-value of 0.0298. Large conformational differences between TGS and sucrose were observed, particularly in the conformation of the glycosidic linkage. These differences originate from chlorine substitution, which affects intramolecular hydrogen bonding and sweet-taste glucophores.     

Angiotensin II and angiotensin-(1-7) inhibit the inner cortex Na+ -ATPase activity through AT2 receptor

In the present paper, the modulation of the basolateral membrane (BLM) Na⁺-ATPase activity of inner cortex from pig kidney by angiotensin II (Ang II) and angiotensin-(1–7) (Ang-(1–7)) was evaluated. Ang II and Ang-(1–7) inhibit the Na⁺-ATPase activity in a dose-dependent manner (from 10⁻¹¹ to 10⁻⁵ M), with maximal effect obtained at 10⁻⁷ M for both peptides. Pharmacological evidences demonstrate that the inhibitory effects of Ang II and Ang-(1–7) are mediated by AT₂ receptor: The effect of both polypeptides is completely reversed by 10⁻⁸ M PD 123319, a selective AT₂ receptor antagonist, but is not affected by either (10⁻¹²–10⁻⁵ M) losartan or (10⁻¹⁰–10⁻⁷ M) A779, selective antagonists for AT₁ and AT_(1–7) receptors, respectively. The following results suggest that a PTX-insensitive, cholera toxin (CTX)-sensitive G protein/adenosine 3′,5′-cyclic monophosphate (cAMP)/PKA pathway is involved in this process: (1) the inhibitory effect of both peptides is completely reversed by 10⁻⁹ M guanosine 5′-O-(2-thiodiphosphate) (GDPβS; an inhibitor of the G protein activity), and mimicked by 10⁻¹⁰ M guanosine 5′-O-(3-thiotriphosphate) (GTPγS; an activator of the G protein activity); (2) the effects of both peptides are mimicked by CTX but are not affected by PTX; (3) Western blot analysis reveals the presence of the G_s protein in the isolated basolateral membrane fraction; (4) (10⁻¹⁰–10⁻⁶ M) cAMP has a similar and non-additive effect to Ang II and Ang-(1–7); (5) PKA inhibitory peptide abolishes the effects of Ang II and Ang-(1–7); and (6) both angiotensins stimulate PKA activity.     

Synthesis, magnetism and crystal structure of [V2O2(μ-OH)2(tpen)]I2·4H2O; a binuclear complex containing the syn-{VO(μ-OH)2VO} core (tpen = tetrakis(2-pyridylmethyl)ethylenediamine)

The reaction of N,N,N′,N′-tetrakis(2-pyridylmethyl)ethylenediamine (tpen) with VCl₃ in CH₃CN yields Cl₃V(tpen)VCl₃ which was hydrolyzed in water in the presence of oxygen affording [V₂O₂(μ-OH)₂(tpen)]I₂·2H₂O, the crystal structure of which has been determined. Asyn-{OV(μ-OH)₂VO}²⁺ core has been identified where the V(IV) centers are antiferromagnetically coupled (J = −150 cm⁻¹;g = 1.80).     

On the reduction behaviour of 2-methoxyethyl and 2-methylthioethyl substituted zirconocene dichlorides: crystal structure of (η,σ-C5Me4CH2CH2S)2Zr

A reduction of previously reported 2-methoxyethyl and 2-methylthioethyl functionalized zirconocenedichlorides (η⁵-C₅Me₄CH₂CH₂EMe)(η⁵-C₅Me₅)(ZrCl₂ (E = O, S) and (η⁵-C₅Me₄CH₂CH₂EMe)(η⁵-C₅Me₄CH₂CH₂E′Me)ZrCl₂ (E = O, S; E′ = O, S) with Mg/Hg in THF leads unexpectedly to the products of O---Me and S---Me bond cleavage (η⁵,σ-C₅Me₄CH₂CH₂E)(η⁵-C₅Me₅)ZrMe (E = O, S), (η⁵,σ-C₅Me₄CH₂CH₂E)(η⁵-C₅Me₄CH₂CH₂E′Me)ZrMe (E = O, S; E′ = O), and (η⁵,σ-C₅Me₄CH₂CH₂S)₂Zr respectively. The crystal structure of (η⁵,σ-C₅Me₄CH₂CH₂S)₂Zr was established by X-ray analysis. At that same time the reduction of (ηsu5-C_{5Me4CH2CH2EMe)(η⁵-C5Me5)ZrCl2 (E> = O, S)} under 1 atm of CO gives either only the dicarbonyl derivative (η⁵-C₅Me₄CH₂CH₂EMe) (η⁵-C₆Me₅)Zr(CO)₂ (E = O) or a complex mixture of products (E = S).     

Gold in organic synthesis Part 2. Preparation of benzyl-alkyl and-arylketones via C---C coupling

Reaction of [Au(η²-Ar){CH₂C(O)R}Cl] (Ar=C₆H₄N=N- Ph-₂, R=Me, C₆H₂(OMe)₃-3′,4′,5′; Ar=C₆H₃(N=NC₆H₄Me- 4′)-2, Me-5, R=Me) with PPh₃ and NaClO₄·H₂O (1:2:1) at room temperature, leads to reductive elimination giving [Au(PPh₃)₂]ClO₄ and the corresponding carbon-carbon coupling product ArCH₂C(O)R. A similar process takes place when complexes [Au(η²-Ar){CH₂C(O)R}(PPh₃)Cl] are refluxed in tetrahydrofuran, through elimination of [Au(PPh₃)Cl].     

Nitrogen atom transfer and redox chemistry of terpyridyl phosphoraniminato complexes of osmium (IV)

Rapid reactions occur between [Os^VI(tpy)(Cl)₂(N)]X (X = PF₆⁻, Cl⁻, tpy = 2,2′:6′,2″-terpyridine) and aryl or alkyl phosphi nes (PPh₃, PPh₂Me, PPhMe₂, PMe₃ and PEt₃) in CH₂Cl₂ or CH₃CN to give [Os^IV(tpy)(Cl)₂(NPPh₃)]⁺ and its analogs. The reaction between trans-[Os^VI(tpy)(Cl)₂(N)]⁺ and PPh₃ in CH₃CN occurs with a 1:1 stoichiometry and a rate law first order in both PPh₃ and Os^VI with k(CH₃CN, 25°C) = 1.36 ± 0.08 × 10⁴ M⁻ s⁻¹. The products are best formulated as paramagnetic d⁴ phosphoraniminato complexes of Os^IV based on a room temperature magnetic moment of 1.8 μ_B for trans-[Os^IV(tpy)(Cl)₂(NPPh₃)](PF₆), contact shifted ¹H NMR spectra and UV-Vis and near-IR spectra. In the crystal structures of trans-[Os^IV(tpy)(Cl)₂( NPPh₃)](PF₆)·CH₃CN (monoclinic, P2₁/n with a = 13.384(5) Å, b = 15.222(7) Å, c = 17.717(6) Å, β = 103.10(3)°, V = 3516(2) ų, Z = 4, R_w = 3.40, R_w = 3.50) and cis-[Os^IV(tpy)(Cl)₂(NPPh₂Me)]-(PF₆)·CH₃CN (monoclinic, P2₁/c, with a = 10.6348(2) Å, b = 15.146(9) ÅA, c = 20.876(6) Å, β = 97.47(1)°, V = 3334(2) ų, Z = 4, R = 4.00, R_w = 4.90), the long Os-N(P) bond lengths (2.093(5) and 2.061(6) Å), acute Os-N-P angles (132.4(3) and 132.2(4)°), and absence of a significant structural trans effect rule out significant Os-N multiple bonding. From cyclic voltammetric measurements, chemically reversible Os^V/IV and Os^IV/III couples occur for trans-[Os^IV(tpy)(Cl)₂(NPPh₃)](PF₆) in CH₃CN at +0.92 V (Os^V/IV) and −0.27 V (Os^IV/III) versus SSCE. Chemical or electrochemical reduction of trans-[Os^IV(tpy)(Cl)₂(NPPh₃)](PF₆) gives isolable trans-Os^III(tpy)(Cl)₂(NPPh₃). One-electron oxidation to Os^V followed by intermolecular disproportionation and PPh₃ group transfer gives [Os^VI(tpy)Cl₂(N)]⁺, [OS^III(tpy)(Cl)₂(CH₃CN)]⁺ and [Ph₃=N=PPh₃]⁺ (PPN⁺). trans-[Os^IV(tpy)(Cl)₂(NPPh₃)](PF₆) undergoes reaction with a second phosphine under reflux to give PPN⁺ derivatives and Os^II(tpy)(Cl)₂(CH₃CN) in CH₃CN or Os^II(tpy)(Cl)₂(PR₃) in CH₂Cl₂. This demonstrates that the Os^VI nitrido complex can undergo a net four-electron change by a combination of atom and group transfers.     

Assessment of substitution in the second pharmacophore of Dmt-Tic analogues

The Dmt-Tic pharmacophore exhibits potent δ-opioid receptor antagonism. Analogues with substitutions in the second pharmacophore with (1, 1′) or without a COOH function (2–9) were synthesized: several had high δ affinity (1′, 2, 7, and 9), but exhibited low to non-selectivity toward μ receptors similar to H-Dmt-Tic-amide and H-Dmt-Tic-ol. Functional bioactivity indicated high δ antagonism (pA₂ 7.4–7.9) (1′, 2, and 9) and modest μ agonism, pEC₅₀ (6.1–6.3) (1′, 2, 8, and 9), but with E_max values analogous to dermorphin. These Dmt-Tic analogues with mixed δ antagonist/μ agonist properties would appear to be better candidates as analgesics than pure μ agonists.     

Isolation, structural elucidation, and partial synthesis of lutein dehydration products in extracts from human plasma

All-E-(3R,6′R)-3-hydroxy-3′,4′-didehydro-β,γ-carotene (anhydrolutein I) and all-E-(3R,6′R)-3-hydroxy-2′,3′-didehydro-β,ε-carotene (2′,3′-anhydrolutein II) have been isolated and characterized from extracts of human plasma using semipreparative high-performance liquid chromatography (HPLC) on a C₁₈ reversed-phase column. The identification of anhydroluteins was accomplished by comparison of the UV-Vis absorption and mass spectral data as well as HPLC-UV-Vis-mass spectrometry (MS) spiking experiments using fully characterized synthetic compounds. Partial synthesis of anhydroluteins from the reaction of lutein with 2% H₂SO₄ in acetone, in addition to anhydrolutein I (54%) and 2′,3′-anhydrolutein II (19%), also gave (3′R)-3′-hydroxy-3,4-dehydro-β-carotene (3′,4′-anhydrolutein III, 19%). While anhydrolutein I has been shown to be usually accompanied by minute quantities of 2′,3′-anhydrolutein II (ca. 7–10%) in human plasma, 3′,4′-anhydrolutein III has not been detected. The presence of anhydrolutein I and II in human plasma is postulated to be due to acid catalyzed dehydration of the dietary lutein as it passes through the stomach. These anhydroluteins have also been prepared by conversion of lutein diacetate to the corresponding anhydrolutein acetates followed by alkaline hydrolysis. However, under identical acidic conditions, loss of acetic acid from lutein diacetate proceeded at a much slower rate than dehydration of lutein. The structures of the synthetic anhydroluteins, including their absolute configuration at C(3) and C(6′) have been unambiguously established by ¹H NMR and in part by ¹³C NMR, and circular dichroism.     

Synthesis and solution behavior of the trinuclear palladium(II) unsaturated carboxylate complexes triangle-Pd3[μ-O2CC(R′) = CHMe]6 (R′ = Me, H): X-ray structure of palladium(II) tiglate (R′ = Me)

The first examples of binary palladium(II) derivatives of unsaturated carboxylic acids are reported. It was found that the interaction of Pd₃(μ-OAc)₆ with the ,β-unsaturated 1-methylcrotonic (tiglic) and crotonic acids leads to the corresponding carboxylates of composition Pd₃[μ-O₂CC(R′) = CHMe]₆, where R′ = Me (1) or H (2). The new compounds have been characterized by elemental analysis, solid and solution IR, ¹H and ¹³C NMR, and ESI mass spectrometry. The crystal structure of 1 has been determined. This molecule displays a central Pd₃ cyclic core with Pd–Pd distances of 3.093–3.171 Å. Each Pd–Pd bond is bridged by a pair of carboxylate ligands, one above and the other below the Pd₃ plane, providing a square planar coordination for each Pd atom in an approximate D_3h overall symmetry arrangement. Solution spectroscopic data show that the bridging η¹:η¹:μ₂ interaction of the carboxylates of 1 and 2 is readily displaced, with a change of the ligand to the terminal (η¹) coordination mode.     

Synthesis and characterization of organomolybdenum and organotungsten halides containing the η-pentabenzylcyyclopentadienyl ligand η-Bz5C5M(CO)3X (M = Mo, W; X = Cl, Br, I). The X-ray molecular structure of η-Bz5C5Mo(CO)3I

An improved synthetic procedure for pentabenzylcyclopentadiene Bz₅C₅H was developed. Six new organomolybdenum and organotungsten halides η⁵-Bz₅C₅M(CO)₃X(M = Mo, W; X = Cl, Br, I) were syntesized through the reaction of η⁵-Bz₅C₅M(CO)₃Li (derived from Bz₅C₅H, n-BuLi and M(CO)₆) with PCl₃, PBr₃ or I₂ and characterized by elemental analysis, IR and ¹H NMR spectroscopy. The structure of η⁵-Bz₅C₅Mo(CO)₃I was determined by single-crystal X-ray diffraction techniques. It crystallized in the monoclinic space groupp P2/c with cell parameters a = 13.294(4), B = 15.147(4), C = 19.027(3) Å, β = 108.32(2)°, V = 3637(2) ų, Z = 4 and D_x = 1.50 g cm⁻³. The final R value was 0.035 for 4564 observed reflections.     

Dinuclear sulfide–thiolate complexes [Pt2(μ-S)(μ-SR)(PPh3)4] as cationic metalloligands

The cationic monoalkylated derivatives of the well-known metalloligand [Pt₂(μ-S)₂(PPh₃)₄], viz. [Pt₂(μ-S)(μ-SR)(PPh₃)₄]⁺ (R = n-Bu, CH₂Ph) are themselves able to act as metalloligands towards the Ph₃PAu⁺ and R′Hg⁺ (R′ = Ph or ferrocenyl) fragments, by reaction with Ph₃PAuCl or R′HgCl, respectively. The resulting dicationic products [Pt₂(μ-SR)(μ-SAuPPh₃)(PPh₃)₄]²⁺ and [Pt₂(μ-SR)(μ-SHgR′)(PPh₃)₄]²⁺ are readily isolated as their hexafluorophosphate salts, and have been fully characterised by spectroscopic techniques and an X-ray structure determination on [Pt₂(μ-SR)(μ-SHgFc)(PPh₃)₄](PF₆)₂.     

η and η olefin complexation by S, S-[Ru(Me2edda)]: a structural change to accommodate bidentate dienes

[Ru^II(Me₂edda)(H₂O)₂] (1), Me₂edda²⁻ = N,N′-dimethylethylenediaminediacetate, exhibits a sterically-controlled molecular recognition in forming η² and η⁴ olefin complexes. 1 exists with an N₂O₂ in-plane set of chelate donors and axial H₂O ligands. The two CH₃ functionalities of Me₂edda²⁻ are poised above and below the N₂O₂ plane of the glycinato rings. Studies herein of the 2,2′-bipyridine complex, [Ru^II(Me₂edda)(bpy)], with bidentate bpy chelation as established via ¹H NMR and electrochemical methods show 1 to be ligated in the S,S configuration with the glycinato rings in-plane as a cis-O form. 1 is sterically discriminating in forming η² complexes with smaller olefins (ethylene, 2-propene, cis-2-butene, methyl vinyl ketone and 3-cyclohexene-1-methanol), but rejects larger decorated ring structures and branched olefins (1,2-dimethyluracil, cyclohexene-1-one 2-methyl-2-propene). η² complexes of 1 have characteristic Ru^II/III DPP waves near 0.55 V which vary slightly with olefin structure. Potentially bidendate dienes (1,3-butadiene, 1,3-cyclohexadiene and 2,5-norbornadiene (nbd) form η⁴ complexes as shown by Ru^II/III waves between 0.94 and 1.30 V, indicate of a highly stabilized Ru^II center by π-backboning. An η²η⁴ ‘equilibrium’ with apparent K = 22 at 25 °C is observed for nbd coordinated to 1. (The η² and η⁴ distribution may be a kinetic one and not a thermodynamic one). To allow formation of the cis η⁴ complexes, 1 must undergo a shift of one or both glycinato donors from the N₂O₂ plane into the axial site away from the dimethyl functionalities. η⁴ chelation by 1,3-butadiene has been confirmed by ¹H NMR spectral assignments of two [Ru^II(Me₂edda)] isomers, one in the axial rans-O glycinato configuration, e.g. 1,3-butadiene is bidentate in the original N₂O₂ plane and a second unsymmetrical glycinato arrangement with in-plane and axial glycinato as well as in-plane and axial η⁴-1,3-butadiene coordination. [Ru^II(hedta)(H₂O)]⁻ (2), hedta³⁻ = N-hydrpxyethylenediaminetriacetate, is less discriminating for olefin structures, forming η² complexes with all eleven olefins and dienes mentioned for studies with 1. However, 2 does not undergo displacement of a carboxylate donor by the second olefin unit of a diene [Ru^II(hedta)(diene)]⁻ complexes possess a pendant non-coordinated olefin and on η²-bound olefin in the complex, indicated by a normal Ru^II(pac)(olefin)Ru^II/III wave near 0.55 V.     

Nitrogen, sulfur and oxygen donor adducts with copper(II) complexes of antitumor 2-formylpyridinethiosemicarbazone analogs: Physicochemical and cytotoxic studies

The preparation of N-, S- and O-donor ligand adducts with CuX⁺(HX=6-methyl-2-formylpyridinethiosemicarbazone (6HL); 2-formylpyridine-2^′-methylthiosemicarbazone (2′L); 2-formylpyridine-4′-methylthiosemicarbazone (4′HL)) is described. The N-donors, 2,2′-bipyridyl (bipy), 4-dimethylaminopyridine (dmap) give the complexes [Cu(6L)(bipy)]PF₆, [Cu(6L)(bipy)]Cl·5H₂O, [Cu(4′L)(bipy)]PF₆, [Cu(6L)(dmap)₂]PF₆·2.5 H₂O and [Cu(4′L)(dmap)₂]PF₆·H₂O which have been characterized by physical and spectroscopic techniques. Pentafluorothiophenolate (pftp) gives S-donor complexes [CuX(pftp)] (X=6L and 4′L) and thiolato co-ordination is proposed on the basis of spectroscopic evidence. Paratritylphenolate (ptp) and HPO²⁻₄ give O-donor complexes [Cu(6L)(ptp)], [Cu(4′L)(ptp)], [{Cu(6L)}₂HPO₄]·4H₂O, and [{Cu(4^′L)}₂HPO₄]·5H₂O which have been characterized by physical and spectroscopic techniques, as have the precursor complexes [Cu(6L)(CH₃COO)]·H₂O, [Cu(4′L)(CH₃COO)], Cu(6HL)(CF₃COO)](CF₃COO)·0.5H₂O, [Cu(4′HL)(CF₃COO)](CF₃COO), [Cu(2′L)Cl₂] and [Cu(2′L)(NO₃)₂]. Protonation constants for the ligands and some of their complexes have been determined. 2-Formylpyridinethiosemicarbazone (HL) complexes of silver, gold, zinc, mercury, cadmium and lead are also discussed. Cytotoxicity against the human tumor cell line HCT-8 and antiviral data for selected compounds are presented.     

Chiral macrocyclic compounds from lactose derivatives

The reaction of benzyl 2,6,6′-tri-O-benzyl-3′,4′-O-isopropylidene-β-lactoside with 1,11-ditosyloxy-3,6,9-trioxaundecane gave benzyl 2,6,6′-tri-O-benzyl-3′,4′-O-isopropylidene-3,2′-O--(3,6,9-trioxaundecane-1,11-diyl)-β-lactoside (2, 47%). Acid hydrolysis of 2 and condensation of the product with 1,14-ditosyloxy-3,6,9,12-tetra-oxatetradecane afforded benzyl 2,6,6′-tri-O-benzyl-3′,4′-O-(3,6,9,12-tetraoxa-tetradecane-1,14-diyl)-3,2′-O-(3,6,9-trioxaundecane-1,11-diyl)-β-lactoside (29%). Similarly, the reaction of benzyl 2,6,2′,4′,6′-penta-O-benzyl-β-lactoside with Ts[OCH₂CH₂]₄OTs gave benzyl 2,6,2′,4′,6′-penta-O-benzyl-3,3′-O-(3,6,9-trioxaundecane-1,11-diyl)-β-lactoside (78%). ¹H-N.m.r. spectroscopy has been used to study the formation of host-guest complexes with some of these macrocyclic compounds and benzyl ammonium thiocyanate.     

Cyclic tetranuclear half-sandwich ruthenium(II) complexes with 4,7-phenanthroline and hydroxo bridges: crystal structure, solution behaviour and binding to nucleosides

The reaction between [(η⁶-p-cymene)Ru(H₂O)₃]X₂ and 4,7-phenanthroline (phen) leads to the formation of the rectangular tetranuclear complexes [(η⁶-p-cymene)₄Ru₄(μ-4,7-phen-N⁴,N⁷)₂(μ-OH)₄]X₄ (X = NO₃, 1a; SO₃CF₃, 1b) which have been structurally characterised by X-ray crystallography. ¹H NMR spectroscopic studies suggest the presence of a partially dissociated dinuclear species of type [(η⁶-p-cymene)₂Ru₂(μ-4,7-phen-N⁴,N⁷)(solv)₄]⁴⁺ in equilibrium with the tetranuclear cyclic species found in the solid state. The temperature effect for this equilibrium was studied by variable temperature ¹H NMR experiments in D₂O and MeOD. The results reveal that the proportion of the tetranuclear species increases with the polarity of the solvent which favour stacking interactions between the phenanthroline moieties. In addition, the reactivity of the tetranuclear species towards the nucleosides guanosine (Guo), cytidine (Cyt), 2′-deoxythymidine (Thy) and 2′-deoxyadenosine (dAdo) has been monitored by ¹H NMR as a potential model for the interaction of the 1 species with the probable DNA target. The results reveal that the 1 systems are able to bind the nucleobases endocyclic nitrogen atoms of Guo Cyt, and dAdo.     

The crystal and molecular structures of lithium trimethylenediaminetetraacetatoferrate(III) trihydrate Li[Fe(trdta)]·3H2O and sodium ethylenediamine-N,N′-diacetato-N,N′-di-3-propionatoferrate(II) pentahydrate Na[Fe(eddda)]·5H2O

The crystal structures of Li[Fe(trtda)]·3H₂O and Na[Fe(eddda)]·5H₂O (trtda = trimethylenediaminetetraacetate and eddda = ethylenediamine-N,N′-diacetate-N,N′-di-3-propionate) have been determined by single crystal X-ray diffraction techniques. The former crystal was monoclinic with the space group P2₁/n,a = 17.775(3),b = 10.261(1),c = 8.883(2)Å, β = 95.86(4)° and Z = 4. The latter was also monoclinic with the space group P2₁/n,a = 6.894(2),b = 20.710(6),c = 13.966(3)Å, β = 101.44(2)° and Z = 4. Both complex anions were found to adopt an octahedral six-coordinated structure with all of six ligand atoms of trdta⁴⁻ or eddda⁴⁻ coordinated to the Fe(III) ion, unlike the corresponding edta⁴⁻ complex which is usually seven-coordinate with the seventh coordination site occupied by H₂O. Of the three geometrical isomers possible for the eddda complex, the trans(O₅) isomer was actually found in the latter crystal. Factors determining the structural types of metal–edta complexes are discussed in detail.     

1-Methoxy-, 1-deoxy-11-hydroxy- and 11-hydroxy-1-methoxy-Delta(8)-tetrahydrocannabinols: new selective ligands for the CB2 receptor

Three series of new cannabinoids were prepared and their affinities for the CB₁ and CB₂ cannabinoid recptors were determined. These are the 1-methoxy-3-(1′,1′-dimethylalkyl)-, 1-deoxy-11-hydroxy-3-(1′,1′-dimethylalkyl)- and 11-hydroxy-1-methoxy-3-(1′,1′-dimethylalkyl)-Δ⁸-tetrahydrocannabinols, which contain alkyl chains from dimethylethyl to dimethylheptyl appended to C-3 of the cannabinoid. All of these compounds have greater affinity for the CB₂ receptor than for the CB₁ receptor, however only 1-methoxy-3-(1′,1′-dimethylhexyl)-Δ⁸-THC (JWH-229, 6e) has effectively no affinity for the CB₁ receptor (K_i=3134±110 nM) and high affinity for CB₂ (K_i=18±2 nM).