Excess Volumes of Water + Acetonitrile and Water + Dimethylsulfoxide at 30°C and the Effect of the Excess Thermal Expansivity Coefficients on Derived Thermodynamic Properties

Excess molar volumes of water + acetonitrile, and water + dimethylsulfoxide mixtures were measured at 30°C. Excess thermal expansivity coefficients ^E were calculated from values of at 30° and 25°C previously reported.^(1,2) The ^E of polar mixtures are relatively large, several times 10^-5 K^-1 and as much 10^-4 K^-1, while those of nonpolar mixtures are at most several times 10^-6 K^-1. These values are several percent of the total expansivity coefficient of the mixture and significantly affect thermodynamic calculation of the estimation of isothermal compressibilities and isochoric heat capacities from isentropic compressibilities and isobaric heat capacities.     

Control of stepwise radial complexation in dendritic polyphenylazomethines

The fourth generation of a dendritic polyphenylazomethine (DPA G4) has 2, 4, 8, and 16 imine groups in the first, second, third, and fourth shells, respectively (total, 30 imine groups). DPA G4 can trap 30 equiv of SnCl(2) molecules, because the imine group is complexed with SnCl(2) at a ratio of 1:1. During addition of 30 equiv of SnCl(2) to DPA G4, four shifts in the isosbestic point were observed in the UV-vis spectra, and the amount of SnCl(2) added in each step is in agreement with the number of imine groups in each shell of DPA G4. This result shows that the complexation of the imine groups in DPA G4 with SnCl(2) occurs stepwise in the order of the first, second, third, and fourth shells. The unique stepwise complexation was also observed in DPA G2 and G3 as two and three shifts of the isosbestic point, respectively. The stepwise complexation was supported by TEM, NMR, and a novel shell-selective reduction (SSR) method for imines. An expansion in the molecular size of DPA G4 by the complexation was revealed by molecular modeling and TEM measurements. The stepwise complexation is caused by the different basicity of the imine groups between the shells, which was supported by the chemical shifts of the peaks attributed to the imine carbons in the (13)C NMR spectra. The gradients in the basicity were controlled by the introduction of electron-withdrawing or -releasing groups to the core of the dendrimers; the core imines were complexed last in DPAs having a 2,3,5,6-tetrafluoro or 2,5-dichlorophenyl core due to the low basicity of the core imines. The different complexation pattern was also clearly confirmed by the SSR method.     

CCR5 antagonists as anti-HIV-1 agents. 1. Synthesis and biological evaluation of 5-oxopyrrolidine-3-carboxamide derivatives

A novel lead compound, N-(3-[4-(4-fluorobenzoyl)piperidin-1-yl]propyl)-1-methyl-5-oxo-N-phenylpyrrolidine-3-carboxamide (1), was identified as a CCR5 antagonist by high-throughput screening using [(125)I]RANTES and CCR5-expressing CHO cells. The IC(50) value of 1 was 1.9 microM. In an effort to improve the binding affinity of 1, a series of 5-oxopyrrolidine-3-carboxamides was synthesized. Introduction of 3,4-dichloro substituents to the central phenyl ring (10i, IC(50)=0.057 microM; 11b, IC(50)=0.050 microM) or replacing the 1-methyl group of the 5-oxopyrrolidine moiety with a 1-benzyl group (12e, IC(50)=0.038 microM) was found to be effective for improving CCR5 affinity. Compound 10i, 11b, and 12e also inhibited CCR5-using HIV-1 envelope-mediated membrane fusion with IC(50) values of 0.44, 0.19, and 0.49 microM, respectively.     

Isolation and structure of monomethylated GM3-type ganglioside molecular species from the starfish Luidia maculata

Two monomethylated GM(3)-Type ganglioside molecular species, 1 and 2, have been obtained from the polar lipid fraction of the chloroform/methanol extract of the starfish Luidia maculata. The structures of these gangliosides have been determined on the basis of chemical and spectroscopic evidence as 1-O-[8-O-methyl-(N-acetyl-alpha-D-neuraminosyl)-(2-->3)-beta-D-galactopyranosyl-(1-->4)-beta-D-glucopyranosyl]-ceramide (1) and 1-O-[8-O-methyl-(N-glycolyl-alpha-D-neuraminosyl)-(2-->3)-beta-D-galactopyranosyl-(1-->4)-beta-D-glucopyranosyl]-ceramide (2). The ceramide moieties were composed of heterogeneous unsubstituted fatty acid, 2-hydroxy fatty acid, sphingosine and phytosphingosine units. Compound 1, designated as LMG-3, represents new ganglioside molecular species. Compound 2 was a known ganglioside molecular species.     

Nickel(0)-mediated sequential addition of carbon dioxide and aryl aldehydes into terminal allenes

[reaction: see text] Nickel-mediated sequential addition of carbon dioxide and aryl aldehydes into terminal allenes is reported. The reaction proceeded in a diastereoselective manner to afford alpha-methylene-gamma-hydroxy carboxylic acids, which allowed stereoselective preparation of cis-beta, gamma-disubstituted alpha-methylene-gamma-lactones.     

Orally active CCR5 antagonists as anti-HIV-1 agents: synthesis and biological activity of 1-benzothiepine 1,1-dioxide and 1-benzazepine derivatives containing a tertiary amine moiety

The search for orally active CCR5 antagonists was performed by chemical modification of the 1-benzothiepine 1,1-dioxide 3 and 1-benzazepine 4 lead compounds containing a tertiary amine moiety. Replacement of methyl group with a 2-(C(2-4) alkoxy)ethoxy group at the 4-position on the 7-phenyl group of the 1-benzothiepine ring resulted in both enhanced activity and significant improvement in the pharmacokinetic properties upon oral administration in rats. Introduction of C(2-4) alkyl, phenyl or (hetero)arylmethyl groups as the 1-substituent on the 1-benzazepine ring together with the 2-(butoxy)ethoxy group led to further increase of activity. Among the 1-benzazepine derivatives, the isobutyl (6i), benzyl (6o) or 1-methylpyrazol-4-ylmethyl (6s) compounds were found to exhibit highly potent inhibitory effects, equivalent to the injectable CCR5 antagonist 1, in the HIV-1 envelope-mediated membrane fusion assay. In particular, compound 6s showed the most potent CCR5 antagonistic activity (IC(50)=2.7 nM) and inhibitory effect (IC(50)=1.2 nM) on membrane fusion, together with good pharmacokinetic properties in rats. The synthesis of 1-benzothiepine 1,1-dioxide and 1-benzazepine derivatives and their biological activity are described.     

Stepwise photocleavage of two C-O bonds of 1,8-bis[(4-benzoylphenoxy)-methyl]naphthalene with three-step excitation using three-color, three-laser flash photolysis

Stepwise photocleavage of two naphthylmethyl-oxygen bonds of 1,8-bis[(4-benzoylphenoxy)methyl]naphthalene (1,8-(BPO-CH2)2Np, 1) was observed during three-color, three-laser flash photolysis at room temperature. The mechanism from 1 to the final product, acenaphthene (2), was clearly elucidated. The first (308 nm, 5 mJ pulse-1) XeCl laser excited 1 to the lowest triplet excited state 1(T1), in which the excited energy was localized in the naphthalene moiety, but the C-O bond cleavage did not occur. The second (430 nm, 7 mJ pulse-1) OPO laser excited 1(T1) to the higher triplet excited states 1(Tn) in which the excited energy is delocalized in the naphthalene moiety and C-O bonds, and one C-O bond cleavage occurred. The third (355 nm, 10 mJ pulse-1) YAG laser excited the carbon-centered radical in the ground state 1-(BPO-CH2)NpCH2*(D0) to its excited states 1-(BPO-CH2)NpCH2*(Dn), from which the second C-O bond cleavage occurred to give 2 as the final product. This is a successful example of stepwise cleavage of two equivalent C-O bonds in a molecule using three-color three-laser photolysis method.     

Potent and specific sialyltransferase inhibitors: imino-linked 5a'-carbadisaccharides

Methyl 5a'-carba-beta-lactoside, imino-linked, has been shown to possess potent and specific inhibitory activity (IC50 = 185 microM) toward rat recombinant alpha2,3-sialyltransferase.     

Synthesis in the diazasteroid group. III . Syntheses of the 8,16- and 8,17-diazasteroid systems

By using 3-pyrrolidone derivatives as a source of the D ring, the following five diazasteroids were synthesized: 8,16-diaza-2,3-dimethoxy-15,15,16-trimethylgona-1,3,5(10),13-tetraen-12-one (VII), 8,16-diaza-2,3-dimethoxy-16-acetylgona-1,3,5(10),13-tetraen-12-one (X), 8,17-diaza-2,3-dimethoxy-17-acetylgona-1,3,5(10),13-tetracn-12-one (XI), 8,16-diaza-16-acetylgona-1,3,5(10), 13-tetraen-12-one (XII), and 8,17-diaza-17-acetylgona-1,3,5(10),13-tetraen-12-one (XIII).     

Enantioselective synthesis of the bottom-half of chlorothricolide

The first enantioselective synthesis of a chlorothricolide intermediate is described. The synthesis features the intramolecular Diels-Alder reaction of tetraene 3.