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Acylated C-glycopyranosyl thioformamides of d -gluco, d -galacto, and d -xylo configuration were obtained by treating the corresponding glycosyl cyanides with hydrogen sulfide in the presence of triethylamine. The thioformamides gave 3,5-bis-(β- d -glycopyranosyl)-1,2,4-thiadiazoles in reactions with potassium bromate and sodium dithionite in dichloromethane–water biphasic solvent mixture. Deprotected derivatives were prepared by Zemplen deacylation.

The reaction of per-O-acetylated 1-bromo-1-deoxy-α- d -arabinopyranosyl cyanide with thiocyanate ions gave the corresponding 1-deoxy-1-thiocyanato-α- and β- d -arabinopyranosyl cyanides. In the reaction of the per-O-acetylated 1-bromo-1-deoxy-β- d -xylopyranosyl cyanide and its per-O-benzoylated β- d -glucopyranosyl analogue the corresponding 2-hydroxy-glycal esters formed in addition to the anomeric pair of thiocyanato-cyanides. The formation of 2,3,4,6-tetra-O-benzoyl-α- d -glucopyranosyl thiocyanate was demonstrated in the reaction of benzobromoglucose with thiocyanate ions. The equilibrium constant between 2,3,4,6-tetra-O-acetyl-1-deoxy-1-thiocyanato-α- and β- d -galactopyranosyl cyanides was determined. Based on this value, the equilibrium ratio for the 2,3,4,6-tetra-O-acetyl-α- and β- d -galactopyranosyl thiocyanates was calculated to be 94:6, and the anomeric effect of the SCN group was estimated to exceed 3 kcal/mol. X-Ray crystallographic data support endo- and exo-anomeric effects of the SCN moiety.

Reaction of 2,3,4,6- tetra -O- acetyl-1-bromo-1-deoxy -β- d -galactopyranosyl cyanide (4) with thiocyanate ions results in the formation of both anomers of per-O-acetylated 1-deoxy-1-thiocyanato- d -galactopyranosyl cyanides (5a and 5b). The thiocyanate group in these products is resistant to isomerization into isothiocyanate even at elevated temperatures. The X-ray structure of 5a is consistent with the operation of an exo-anomeric effect for the thiocyanate group. Compounds 5a and 5b react with hydrogen sulfide under mild conditions to yield galactopyranosylidene-spiro-thiazolidine (8) and -thiazoline (9, 12, and 13) derivatives.

[RhCl(CO)(PEt3)2] catalyses the carbonylation of methanol in the presence of MeI and water at a rate 1.8 times that for [RhI2(CO)2]– at 150 °C. The reaction is first order in [MeI] and zero order in pCO. However, the phosphine complex degrades to [Rh(CO)2I2]– during the course of the reaction. Stoichiometric studies show that the rate of oxidative addition of MeI to [RhI(CO)(PEt3)2] is 57 times faster than to [RhI2(CO)2]– at 298 K and that [RhMeI2(CO)(PEt3)2] can be isolated and crystallographically characterised. Combination of the methyl and carbonyl ligands to give the acyl intermediate occurs 38 times slower for [RhMeI2(CO)(PEt3)2] than for [RhMeI3(CO)2]– but the steady state concentration of the intermediates is different in that [Rh(COMe)I2(PEt3)2] is thermodynamically less stable than [RhMeI2(CO)(PEt3)2]. In CH2Cl2, [Rh(COMe)I2(CO)(PEt3)2] reductively eliminates MeCOI. [RhI(CO)(PEt3)2] reacts with CO to give [RhI(CO)2(PEt3)2]. Catalyst degradation occurs via [RhHI2(CO)(PEt3)2], formed by oxidative addition of HI to [RhI(CO)(PEt3)2], which reacts further with HI to give [RhI3(CO)(PEt3)2] from which [Et3PI]+ reductively eliminates and is hydrolysed to give Et3PO. In the presence of water, much less [RhI3(CO)(PEt3)2] and Et3PO are formed so the catalyst is more stable, but loss of [Et3PMe]+ and [Et3PH]+ from [RhMeI2(CO)(PEt3)2] or [RhHI2(CO)(PEt3)2], respectively, lead to catalyst deactivation. The rate determining step of the catalytic reaction in the presence of water is MeI oxidative addition to [RhI(CO)(PEt3)2], but in the absence of water there is evidence that it may be reductive elimination of MeCOI from [Rh(COMe)I2(CO)(PEt3)2]. [RhMeI2(CO)(PEt3)2] has mutually trans phosphines and the methyl group trans to I.

The synthesis, separation and stereochemistry of 1-epimeric (k)-1-thioflavanone 1-oxide isomers with equatorial phenyl group are described. The higher melting isomer (2a) has a 12-cis-, the lower melting one (2b) a 1,2-trans configuration. 1H NMR and mass spectral data for both isomers and X-ray diffraction analysis of 2a are also presented.

The diastereoselective 1,3-dipolar cycloaddition reactions of chiral alkenes with a nitrilimine derived from d -galactose phenylhydrazone were studied. The best stereoselectivity was observed with N-acryloyl-(−)-camphor sultam 9, as the chiral inductor, to produce compound 8.

Reaction of (EE)-1-morpholino-2-methylpenta-1,3-diene 1a with dimethyl 1,2,4,5-tetrazine-3,6-di-carboxylate 2 in acetonitrile solution gives dimethyl 2,5-dimethyl-3-morpholino-8,9-diaza-tricyclo[2.2.2.02,6]oct-8-ene-1,4-dicarboxylate 4a, in high yield (79%) and with high apparent diastereoselectivity; the 1-(4-methylpiperazino) analogue 1b similarly gives compound 4b (66%). Compounds 4a and 4b are the first recorded representatives of this bridged tricyclic ring system. In contrast 2-methyl-1-morpholinocyclopentadiene 5 reacts with 2 mol. equiv. of the tetrazine 2, giving the cyclopentadipyridazine 6.

The novel µ3-hydroxotrioxoborato-capped cluster [Nb3{µ3-BO3(OH)}(µ-O)3{HB(pz)3}3] 1 has been obtained following evaporation to dryness of aqueous HCl solutions of [Nb3(µ3-Cl)(µ-O)3(OH2)9]4+ and treatment with ethanolic potassium hydridotris(pyrazol-1-yl)borate, K[HB(pz)3]. The capping borate group derives from hydrolysis of a HB(pz)3– ligand in the presence of the aqua precursor. Air oxidation of 1 results in complete fragmentation, loss of the borate cap and reassembly in the form of a rectangular tetranuclear oxo-bridged product.

Two new pyridine-containing limonoids, xylogranatopyridines A and B (1 and 2) and their formal precursor, prexylogranatopyridine (3) were isolated from the twigs and leaves of the Chinese mangrove, Xylocarpus granatum. Xylogranatopyridine B (2) possesses an unprecedented rearranged B-ring together with a seco-ring A, supporting the biogenetic connection of 1–2 with 3. The chemical structures were elucidated by means of detailed spectroscopic analysis and X-ray single-crystal diffraction. The absolute configurations were assigned using electronic solid-state circular dichroism (ECD) supported by time-dependent density functional theory (TDDFT) ECD calculations and X-ray analysis. Xylogranatopyridine A (1) exhibited a significant inhibitory activity against protein tyrosine phosphatase 1B (PTP1B) with an IC50 value of 22.9 μM. This is the first report of PTP1B inhibitory activity of limonoids.

The heptadentate ligand OBETA (2,2'-oxybis(ethylamine)-N,N,N',N'-tetraacetic acid) was reported to form complexes with Ln(3+) ions more stable than those formed by the octadentate and more popular congener EGTA (ethylene glycol O,O'-bis(ethylamine)-N,N,N',N'-tetraacetic acid). The structural features leading to this puzzling coordination paradox were investigated by X-ray diffraction, solution state NMR, molecular modeling, and relaxometric studies. The stability constant of Gd(OBETA) (log KGdL = 19.37, 0.1 M KCl) is 2 orders of magnitude higher than that of the higher denticity analogue Gd(EGTA) (log KGdL = 17.66, 0.1 M KCl). The half-lives (t1/2) for the dissociation reactions of Gd(OBETA) and Gd(EGTA) ([Cu(2+)]tot = 0.2 mM, [Cit(3-)]tot = 0.5 mM, [PO4(3-)]tot = 1.0 mM, and [CO3(2-)]tot = 25 mM at pH = 7.4 and 25 °C in 0.1 M KCl solution) are 6.8 and 0.63 h, respectively, reflecting the much higher inertness of Gd(OBETA) near physiological conditions. NMR studies and DFT calculations using the B3LYP functional and a large-core ECP indicate that the [Gd(OBETA)(H2O)2](-) complex most likely exists in solution as the Δ(λλ)(δδδδ)A/Λ(δδ)(λλλλ)A enantiomeric pair, with an activation free energy for the enantiomerization process of ∼40 kJ·mol(-1). The metal ion is nine-coordinate by seven donor atoms of the ligand and two inner-sphere water molecules. The X-ray crystal structure of [C(NH2)3]3[Lu(OBETA)(CO3)]·2H2O is in agreement with the predictions of DFT calculations, the two coordinated water molecules being replaced by a bidentate carbonate anion. The (1)H NMRD and (17)O NMR study revealed that the two inner-sphere water molecules in Gd(OBETA) are endowed with a relatively fast water exchange rate (kex(298) = 13 × 10(6) s(-1)). The higher thermodynamic stability and inertness of Ln(OBETA) complexes, peaking in the center of the 4f series, combined with the presence of two coordinated water molecules suggests that Gd(OBETA) is a promising paramagnetic probe for MRI applications.

Improved methods of synthesis are reported for FcCOC 6 H 4 F-4 1a , FcCOC 6 H 4 OMe-4 1b and Fcd(COC 6 H 4 OMe-4) 2 2b [Fc = (C 5 H 5 )Fe(C 5 H 4 ); Fcd = (C 5 H 4 )Fe(C 5 H 4 )]: demethylation of 1b and 2b , using AlCl 3 in 1,1,2-trichloroethane, yields FcCOC 6 H 4 OH 1f and Fcd(COC 6 H 4 OH) 2 2f respectively. Acylation of ferrocene using 4-phthalimidobenzoyl chloride yields 4-(phthalimidobenzoyl)ferrocene 1c , hydrazinolysis of which yields FcCOC 6 H 4 NH 2 -4 1d . Crystal structures are reported for 1d, 1f and 2f : in 1d and 1f the molecules are linked into spiral chains by means of N-H ⋯ O=C and O-H ⋯ O=C hydrogen bonds respectively; in 2f the O-H ⋯ O=C hydrogen bonds link the centrosymmetric molecules into continuous two-dimensional nets, two independent sets of which are interwoven.

Ion pairs consisting of N-substituted derivatives of 1,3,5-triaza-7-phosphaadamantane (pta-R; R = benzyl, butyl, hexyl) as cations and monosulfonated triphenylphosphine (mtppms) as anion were synthesized and characterized (including X-ray diffraction, too). These ion pairs act as bidentate phosphorus ligands in reactions with [(η6-C10H14)RuCl2]2, yielding mononuclear or dinuclear half sandwich Ru(II) complexes. Bisphosphine 3 of good water-solubility was synthesized in reaction of pta with 1,4-bis(chloromethyl)benzene and used for the synthesis of the water-soluble dinuclear complex [{(η6-C10H14)RuCl2}2(μ-3)]Cl2.

Reaction of mono-sulfonated triphenylphosphine in water with certain activated olefins (for example maleic acid or fumaric acid) yields the corresponding phosphonium salt under very mild conditions. This interaction promotes the formation of the catalytically active species in the hydrogenation of the olefin catalyzed by the rhodium complex of the phosphine.

Microwave heating of the vinylic amines (VII) and their pyridazinone analogues such as (XII) allows a new and straightforward access to fused azecine ring systems like (VIII) and (XIII).

Reaction of (EE)-1-morpholino-2-methylpenta-1,3-diene 1a with dimethyl 1,2,4,5-tetrazine-3,6-di-carboxylate 2 in acetonitrile solution gives dimethyl 2,5-dimethyl-3-morpholino-8,9-diaza-tricyclo[2.2.2.02,6]oct-8-ene-1,4-dicarboxylate 4a, in high yield (79%) and with high apparent diastereoselectivity; the 1-(4-methylpiperazino) analogue 1b similarly gives compound 4b (66%). Compounds 4a and 4b are the first recorded representatives of this bridged tricyclic ring system. In contrast 2-methyl-1-morpholinocyclopentadiene 5 reacts with 2 mol. equiv. of the tetrazine 2, giving the cyclopentadipyridazine 6.

The speciations of two drug candidate ligands, 2-hydroxypyridine-N-oxide (Hhpno) and 2-mercaptopyridine-N-oxide (Hmpno), with vanadate (V(V)) were determined at 25.0 degrees C and 0.20 mol dm(-3) KCl by pH-metric and (51)V-NMR methods. At pH 7.4, the two predominant compounds with both ligands are the VO(2)L(2) and VO(2)L(OH). NH(4)[VO(2)(hpno)(2)] x 3 H(2)O was prepared in solid form, and its crystal structure was determined by X-ray diffraction. The stabilities of the complexes VO(2)L(2) of five drug candidate ligands were compared at pH 7.4. In view of the stability sequence hpnomaltol approximately hdp (Hhdp: 3-hydroxy-1,2-dimethyl-4-pyridinone)mpnopicolinic acid, the first two of these ligands were chosen for equilibrium studies with apotransferrin (apoTf) competition. The V(V)-apoTf stability constants (log K(1) = 6.03 +/- 0.10; log K(2) = 5.46 +/- 0.18) determined by (51)V-NMR spectroscopy were confirmed by ultrafiltration. Both methods proved that there seems to be no hydrogencarbonate-vanadate competition for the apoTf anion-binding positions. The other potential high molecular mass V(V) binder in the serum is human serum albumin (HSA). As no interaction was detected by (51)V-NMR spectroscopy or fluorimetry, the binding properties of HSA were quantified on the basis of literature data. As a final conclusion, speciation modeling calculations suggest that, under serum conditions, apoTf is probably the primary metal ion binder, even in the presence of the most stable V(V) carrier ligands hpno and maltol and HSA plays a negligible role in V(V) binding.

Novel straightforward syntheses of naphtho-fused azepines and benzazonine via tert-amino effect are described. Starting from 1-naphthylamine, 8-/N,N-dialkylaminonaphthalene-1-carbaldehydes could be obtained in two steps. The aldehyde was prepared by a Suzuki reaction of 8-bromonaphthalene-1-carbaldehyde with ortho-pyrrolidinophenylboronic acid. Treatment of aldehydes with active methylene compounds afforded naphthazepines and novel benzazonine ring system, respectively, through rearrangement of isolable vinyl intermediates or benzo[de]quinolinium derivatives or without isolation of any intermediates. A mechanistic investigation supports an intramolecular hydride transfer for the ring closure to azepine or azonine. Our results indicate that the tert-amino effect may provide a valuable approach to the synthesis of ortho- and peri-fused aza-ring systems.

Dioxane-type (9'-anthracenyl)methylene acetal of methyl 2,3-di-O-methyl-alpha-D-glucopyranoside was cleaved with LiAlH(4)/AlCl(3) (3:1) or with Na(CN)BH(3)-HCl regioselectively to provide the 4- or 6-O-(9'-anthracenyl)methyl ether, respectively. Hydrogenolytic reaction of the exo and endo isomers of dioxolane-type acetals proved to be directed by the configuration of the acetalic carbon as well as by the intramolecular participation of the adjacent-free hydroxyl; ring-opening reaction of the endo isomer of the methyl 2,3-O-(9'-anthracenyl)methylene-alpha-L-rhamnopyranoside took place with complete selectivity resulting in the axial (9'-anthracenyl)methyl ether, whereas a 1:1 mixture of the axial and equatorial ethers was formed upon the same reaction of the exo isomer. Catalytic hydrogenation of the sugar acetals resulted in (9',10'-dihydro-9'-anthracenyl)methylene derivatives without affecting the acetalic center. High-temperature molecular dynamics simulations and DFT (Density Functional Theory) geometry optimizations were carried out to study the conformation of the dioxane-type (9',10'-dihydro-9'-anthracenyl)methylene acetal.

Phenanthridines and azocines fused to two benzene rings or one benzene and one pyridazinone ring, which are otherwise difficult to access, were prepared via two new extensions of the tert- ' amino effect. The synthetic pathway includes three steps:i) Suzuki ] reaction of an ortho-functionalized phenylboronic acid with ortho- ] disubstituted benzenes or pyridazinones; ii) the Knoevenagel condensation reaction of the biaryl aldehydes formed with active methylene compounds to obtain vinyl derivatives or, through their cyclization, phenanthridines via a tert-amino effect; and iii) thermal isomerization of vinyl or phenanthridinium compounds to fused azocines via another type of tert-amino effect.

The heptadentate ligand 1,4-bis(hydroxycarbonylmethyl)-6-[bis(hydroxycarbonylmethyl)]amino-6-methylperhydro-1,4-diazepine (AAZTA) and its derivatives were recently reported to give stable complexes with Gd(3+) with superior efficiency as MRI contrast agents. Nevertheless, only preliminary data are available on the coordination behavior of this interesting ligand. In this work, thermodynamic and kinetic stability data are determined for the formation of complexes with AAZTA and the lanthanoid metal ions, and other divalent metal ions of interest for this application. The AAZTA ligand binds the lanthanoid ions with log K(ML) values of 17.53-21.85 with its affinity steadily increasing from La(3+) to Lu(3+), suggesting that the seven-membered skeleton is better suited to accommodate smaller metal ions. Even though the denticity is lower, the stability of the heavier lanthanoid complexes is comparable to those of the classical ligand diethylenetriaminepentaacetic acid (DTPA). The transmetalation reactions of [Gd(AAZTA)](-) with Cu(2+) and Eu(3+) predominantly occur through proton-assisted dissociation of the complex. The role of the direct attack of Cu(2+) or Eu(3+) in the exchange reactions is limited, although the formation of dinuclear complexes decreases the proton-assisted dissociation. Near physiological conditions, [Gd(AAZTA)](-) is significantly more inert than [Gd(DTPA)](2-), allowing its potentially safe use as contrast agent in magnetic resonance imaging.

A new analogue of the antitumor pericosines possessing a bicyclo[2.2.2]octene skeleton has been synthesized from methyl gallate using oxidative dearomatization and regio- and diastereoselective Diels–Alder reaction as the key steps.

(O-Peracylated alpha-D-gluco- and -galacto-hept-2-ulopyranosylbromide)onamides gave the corresponding (alkyl beta-D-glyco-hept-2-ulopyranoside)onamides under Koenigs-Knorr conditions, and similar aryl glycosides were obtained with sodium phenolates; (aryl and hetaryl 2-thio-beta-D-gluco-hept-2-ulopyranoside)onamides were formed with thiophenols in the presence of K(2)CO(3) in acetone, and reactions with aniline in CH(2)Cl(2) furnished (N-phenyl beta-D-glyco-hept-2-ulopyranosylamine)onamides. Some deprotected derivatives of d-gluco configuration obtained by the Zemplen protocol showed no significant inhibition against rabbit muscle glycogen phosphorylase b.

A series of different N-heterocyclic carbenes (NHCs) were reacted with 3,6-bis(3‘,5‘-dimethylpyrazolyl)-tetrazine in the presence of an inorganic carbonate to provide access to a hitherto unprecedented compound class. The formed tetrazine derivatives bearing the NHC in the 3-position and an oxygen in the 6-position show a quinoidal-like structure, according to physical examinations and X-ray crystallography.

The sensing ability of three 1,10-diaza-18-crown-6 based sensors bearing a coumarin fluorophore was studied and compared with the analogous monoaza-18-crown-6 sensor. Coordination experiments between hosts and organic ammonium salts with varying steric demand were studied using fluorescence and 1 H NMR spectroscopy. We have found that the fluorescent signal generated on complexation was greatly influenced by the structure of the sensor. Surprisingly, in two cases, we observed the decrease of fluorescence on complexation, which was attributed to changes in the conformational dynamics of the sensors on complexation.

Aromatic and aliphatic aldehydes can be reduced to the corresponding alcohols by hydrogen transfer from formate using, as catalysts, water-soluble complexes of Ru(II), Rh(I) and Ir(I) with monosulphonated triphenylphosphine (mSPφ)2, in aqueous/organic biphasic systems without phase transfer catalysts. HRu(O2CH)(mSPφ)2)3 was identified as the key intermediate in the processes catalyzed by RuCl2(mSPφ2)2 in an excess of phosphine. Olefinic double bonds (including those in α,β-unsaturated aldehydes), as well as substitutents of the aromatic ring, are not affected. Attempted catalysis of the transfer of benzaldehyde from the organic to the aqueous phase by β-cyclodextrin resulted in inhibition of the metal complex-catalyzed transfer hydrogenation.

A series of different N-heterocyclic carbenes (NHCs) were reacted with 3,6-bis(3‘,5‘-dimethylpyrazolyl)-tetrazine in the presence of an inorganic carbonate to provide access to a hitherto unprecedented compound class. The formed tetrazine derivatives bearing the NHC in the 3-position and an oxygen in the 6-position show a quinoidal-like structure, according to physical examinations and X-ray crystallography.

Anomeric pairs of ketopyranosyl glycosides with various substituents at C(alpha), C(beta) and C(gamma) were synthesized from the corresponding thioglycosides, and the influence of the C(alpha)-C(beta)-C(gamma)-H(gamma) torsion angle and substituent effects on the three-bond carbon-proton couplings was studied. The cis coupling constants range from 1 to 2Hz. The trans couplings are generally as small as 2.3-2.6Hz; however, for compounds bearing an unsubstituted gamma-carbon, a relatively large trans coupling was measured (4.8Hz). An S-ethyl group at the beta-position increases the cis coupling (up to 3.2Hz) compared to the corresponding O-glycosides.

A series of N-heterocyclic carbene precursors, containing an imidazoline or tetrahydropyrimidine framework, were prepared from omega-chloroalkanoyl chlorides. The sequential attachment of nitrogen nucleophiles and subsequent ring closure gave, depending on the reagents used, either the desired dihydroimidazolium and tetrahydropyrimidinium salts or their parent heterocycles. In this latter case, the second substituent was introduced in an alkylation step. The preparation of carbene precursors bearing chiral or bulky substituents was acieved with comparable efficiency.

The complex formed between 1,3-diamino-2-hydroxypropane-N,N,N',N'-tetraacetic acid (H4L-OH) and Nd3+ at pH 7.5 was found to be a dinuclear dimer in the solid state by X-ray crystallography. In the complex K4[Nd2(L-O)2(H2O)2].14H2O each ligand is coordinated to both Nd3+ atoms with an iminodiacetate group (the Nd3+-Nd3+ distance is 3.9283(8) A). The alcoholic OH groups are deprotonated, and the alkoxo oxygens are coordinated to both Nd3+ in a bridging position. The Nd3+ ions are nine-coordinated with one water molecule per Nd(III) ion in the inner sphere. The complex K4[Nd2(L-O)2(H2O)2].14H2O has an inversion center, and the space group is P1. Two of the K+ counterions are six-coordinated, while the other two K+ ions are eight-coordinated; polar polymeric water-K+ layers are formed between the apolar ligand layers via the bridging water molecules. The dinuclear dimer complexes are also present in aqueous solution. The proton relaxivities of the Gd3+ complex decrease with the increase of pH, and at pH > 6, the low relaxivity values indicate the probable absence of H2O in the inner sphere and the predominance of the eight-coordinated dimer species [Gd2(L-O)2].4- The results of ESI-TOF MS studies of the complexes of La3+, Nd3+, and Lu3+ proved the formation of dinuclear dimers in dilute (0.25 mM) solutions. pH-potentiometric titrations indicate the formation of complexes with 1:1 (Ln(L-OH)-, Ln(HL-OH), and Ln2(L-O)24-) and 2:1 (Ln2(L-O)+) metal-to-ligand ratios. The stability constants of the Ln(L-OH)- species increase from La3+ (log K = 10.19) to Lu3+ (log K = 14.08). The alcoholic OH group of the Ln(L-OH)- species dissociates at unusually low pH values. The pH range of dissociation shifts to lower and lower pH's with the increasing atomic number of the lanthanides. This pH range is about 4-7 for the La3+ complex and 1-4 for the Lu3+ complex. The results of 1D and 2D 1H and 13C NMR studies of the La3+ complex, the number and multiplicity of signals, and the values of coupling constants are in agreement with the dinuclear dimer structure of the complex in solution.

The CD spectra are reported for a series of 1,3-dioxane-type 4,6-O-(2'-naphthyl)methylene acetals of carbohydrates with and without interacting aromatic protective groups on the C-1, C-2, and C-3 hydroxy groups. In the absence of interacting chromophores, the signs of the (1)B transitions are not sensitive to the configuration of C-4, while the signs of the weak (1)L(a) bands are opposite in the galacto and gluco derivatives. The equatorial parallel conformation is found to be the preferred conformation of the 2-naphthyl group in the solid state by X-ray diffraction. The intense (1)B(a) and (1)B(b) transitions of the naphthalene chromophore allowed a safe configurational assignment by exciton coupled interaction with the aromatic protective groups in para-methoxyphenyl-beta-D-glycosides. The origin of the observed CEs were deduced and the additivity of the interactions was studied. The direction of the hydrogenolytic cleavage of 4,6-O-(2'-naphthyl)methylene acetal of carbohydrates could also be detected by the (1)B(b) transition of the 2-naphthyl chromophore.

Acylated anhydro-aldononitriles (glycosyl cyanides) were transformed into anhydro-aldose tosylhydrazones by Raney–nickel reduction in the presence of tosylhydrazine in a one-pot reaction. The configuration of the CN double bond in these hydrazones was E as proven by 15N–1H coupling constants as well as X-ray crystallography. Thermolysis in refluxing 1,4-dioxane of the sodium salts of the tosylhydrazones obtained by sodium hydride (generally 10 eq.) resulted in the formation of anhydro-1-deoxy-ald-1-enitols (exo-glycals). “Dimeric” N-glycosylmethyl anhydro-aldose tosylhydrazones could also be isolated when the use of less base caused incomplete deprotonation of the starting compounds. This two-step procedure constitutes a novel, reasonably short synthetic pathway to acylated exo-glycals from the readily available glycosyl cyanides.

The first enantioselective synthesis of trans-(6aS,11aR)-pterocarpan [(+)-2] and its conversion to cis-(6aS,11aS)-pterocarpan [(+)-1] was achieved starting from racemic 2'-benzyloxyflavanone (rac-3). Their stereochemistry was deduced by X-ray analysis of the ketal intermediate (-)-5a. The CD study of (+)-1 and (+)-2 allows the configurational assignment of similar pterocarpan derivatives by CD spectroscopy.

Stability constants of the complexes formed in the reaction of [Pd(bpma)] 2 + [bpma=bis(pyridin-2-ylmethyl)amine] with monodentate nitrogen and thioether ligands including uridine, MeUH, cytidine, MeC, EtGH, AcHis, AcHm, AcLys and AcMet were determined by potentiometric method. The coordination chemistry of [Pd(bpmal] 2 + shows a significant similarity to that of [Pd(terpy)] 2 + , but it is different from [Pd(dien)] 2 + . The formation of hydroxo and dinuclear complexes is especially enhanced in the case of [Pd(bpma)] 2 + and [Pd(terpy)] 2 + , but the affinity of palladium(II) ions for the coordination of thioether residues is reduced in the presence of pyridine nitrogen atoms. Stopped-flow kinetic measurements reveal that the substitution reactions of the thioether ligand AcMet are much faster than those of the N-donor cytidine: The presence of the two pyridyl residues significantly enhances the kinetic reactivity of [Pd(bpma)] 2 + as compared to that of [Pd(dien)] 2 + . The Pd-S(thioether) bonded species can be important intermediates in multicomponent systems, but the equilibrium state is characterised by the formation of Pd-N bonded species. The complex [Pd(bpma)NO 3 ]NO 3 has been prepared in solid state and its structure was elucidated by single crystal X-ray diffraction method.

The cis axial/equatorial OH groups of methyl alpha-L- and ethyl 1-thio-alpha-L-rhamnopyranoside, 1,6-anhydro-beta-D-mannopyranose, and 1,6-anhydro-beta-D-galactopyranose were reacted with 2-naphthaldehyde dimethyl acetal to diastereomeric dioxolane-type 2,3-O-(2-naphthyl)methylene or 3,4-O-(2-naphthyl)methylene acetals. The glycosides yielded the exo- and endo-isomers in nearly 1:1 ratio, 1,6-anhydro-beta-D-mannopyranose gave predominantly the endo-, and 1,6-anhydro-beta-D-galactopyranose exclusively endo-isomer. The acetals and some of their fully protected derivatives bearing benzyl or tert-butyldimethylsilyl groups were hydrogenolised with AlH(3) (3LiAlH(4)-AlCl(3)) or with Me(3)N.BH(3)-AlCl(3) reagents. The endo-isomers were cleaved by both reagents to give axial NAP ethers, the exo-isomers of pyranosides furnished equatorial NAP ethers. However, the exo-isomers of pyranoses gave irregular axial ethers with a30-fold enhancement of the reaction rates with respect to the endo-isomer.

On the action of H2 in aqueous solutions, the water soluble analogue of Wilkinson's catalyst, [RhCl(tppms)3][tppmsP(C6H5)2(C6H4SO3Na)], gives [RhH(tppms)3] instead of [RhH2Cl(tppms)3] and this is reflected in the rates and selectivities of hydrogenations using this catalyst.

Arene complexes of Platinum Group Metals (PGM) show various biological effects and there are several promising anticancer drug candidates in this class of compounds. Synergism of biological activity is foreseen when anciliary ligands such as amino acid derivatives or other bioligands are incorporated into the complexes. A series of Ru(II), Os(II), Rh(III) and Ir(III) complexes were studied and interesting kinetic/equilibrium/structural properties could be revealed [1-3]. According to our latest results presented here the N-acetylcysteine complex of the [(η6-Ar)Ru]2+ core (Ar = p-cymene) is a dimer showing bridging thiolate and chloride cordination (Figure 1, a) while a monomeric complex was formed with [S, COO–,NH2] coordination for S-methyl-cysteine when the counter ion is nitrate (Figure 1, b). With methionine an analogous compound was formed (Figure 1, c). Supramolecular analysis of the complexes indicates competing steric/Coulombic/van der Waals interactions and hydrogen bonds. X-ray diffraction and spectroscopic analysis revealed the structure of the complexes both in solution and in the solid state and also support kinetic/equilibrium findings. Acknowledgement: The research was supported by the EU and co-financed by the European Social Fund under the project ENVIKUT (TÁMOP-4.2.2.A-11/1/KONV-2012-0043). The work was supported by the Hungarian Scientific Research Fund (OTKA K76142), too. P.B. thanks members of the EU COST Action CM1105 for motivating discussions. G.B. acknowledges the support of the Bolyai János Scholarship of the Hungarian Academy of Sciences.

It is equally important from theoretical and practical point of view to study aqua complexes of transition metals. Among them, Ru(H2O)6(tos)2 (I, tos=p-toluenesulfonate) can be a versatile starting material in aqueous organometallic chemistry. It offers a genuine chlorine free entry into several classes of the ruthenium chemistry. In situ preparation of catalysts starting from I and the appropriate ligand is also possible. In this work earlier studies on Ru(H2O) 6 2+ has reviewed and new results reported to explore the applicability of Ru(H2O) 6 2+ in synthetic chemistry and catalysis.

In aqueous organometallic chemistry water is often considered solely as a solvent. However, there are several examples when such an assumption is not justified [1]. Water is a strongly coordinating, polar solvent, capable of assisting reactions yielding polar or charged (ionic) products. H2O itself can oxidatively add to a low valent transition metal complex with formation of hydrido-hydroxometal complex compounds. Hydroxometal species are also formed by replacement of anionic ligands (e.g. halides) by OH- (metal ion hydrolysis equilibria). Dissolved salts strongly influence reaction mechanisms involving polar or charged transition states and intermediates. In addition acid/base catalytic reactions of the substrates or products effect rates and selectivities. All these reactions are influenced by the pH which should be regarded of paramount importance in aqueous organometallic catalysis. Presence of a separate water phase in aqueous/organic biphasic reactions may have important consequences on the reaction mechanism due to the separation of reactants, products and intermediates (physical or solubility effects). This paper focusses on a few selected examples of such effects from our research on reactions of or catalyzed by platinum metal complexes with the water soluble phosphines: m-sulfonatophenyldiphenylphosphine (TPPMS) and 1,3,5-triaza-7-phosphaadamantane (PTA).

Chemical resolutions of the rigid, tricyclic 3,4,5,6-tetrahydro-2-methyl-2,6-methano-2H-1-benzoxocin-4-one (6) of biological and chiroptical interest have been performed. The configurational assignment was made by X-ray analysis and chemical correlation of its ketal (+)-9a synthesized with (2R,3R)-butane-2,3-diol. Kinetic resolution of the hydroxy derivative rac-10 by means of lipase from Pseudomonas cepacia proved the most effective procedure for resolution. The stereochemistry of the faster reacting enantiomer (+)-10 was deduced by chemical correlation with the ketal (+)-9. Model compounds (+)-1 and (−)-1 for chiroptical study of the chromane chromophore were also prepared.

[Cp*Co(CO)2] in the presence of PEt3 and MeI catalyses the carbonylation of methanol with initial rates up to 44 mol dm–3 h–1 before decaying to a second catalytic phase with rates of 3 mol dm–3 h–1; [CoI(CO)2(PEt3)2], which is trigonal bipyramidal with axial PEt3 ligands, has been isolated from the final reaction solution.