Stereospecific synthesis of dinucleoside monophosphate aryl esters by using new condensing reagents

Abstract

New condensing reagents, arenesulfonyl 5-(pyridin-2-yl)tetrazoles have been synthesized and used for stereospecific synthesis of dinucleoside monophosphate aryl esters.     

Molecular manipulation of two- and three-dimensional silica nanostructures by alkoxysilylation of a layered silicate octosilicate and subsequent hydrolysis of alkoxy groups

A novel methodology for constructing molecularly ordered silica nanostructures with two-dimensional (2-D) and three-dimensional (3-D) networks has been developed by using a stepwise process involving silylation of a layered silicate octosilicate with alkoxytrichlorosilanes [ROSiCl(3), R = alkyl] and subsequent reaction within the interlayer spaces. Alkoxytrichlorosilanes react almost completely with octosilicate, bridging two closest Si-OH (or -O(-)) sites on the silicate layers, to form new five-membered rings. The unreacted functional groups, Si-Cl and Si-OR, are readily hydrolyzed by the posttreatment with a water/dimethyl sulfoxide (DMSO) or water/acetone mixture, leading to the formation of two types of silicate structures. The treatment with a water/DMSO mixture produced a unique crystalline 2-D silicate framework with geminal silanol groups, whereas a water/acetone mixture induced hydrolysis and subsequent condensation between adjacent layers to form a new 3-D silicate framework. The 2-D structure is retained by the presence of DMSO molecules within the swelled interlayer spaces and is transformed to a 3-D silicate upon desorption of DMSO. The structural modeling suggests that both of the 3-D silicates contain new cagelike frameworks where solvent molecules are trapped even at high temperature (up to 380 degrees C, in the case of acetone). Both 2-D and 3-D silica structures are quite different from known layered silicates and zeolite-like materials, indicating the potential of the present approach for precise design of various silicate structures at the molecular level.     

A Cell‐Targeted Non‐Cytotoxic Fluorescent Nanogel Thermometer Created with an Imidazolium‐Containing Cationic Radical Initiator

A cationic fluorescent nanogel thermometer based on thermo‐responsive N‐isopropylacrylamide and environment‐sensitive benzothiadiazole was developed with a new azo compound bearing imidazolium rings as the first cationic radical initiator. This cationic fluorescent nanogel thermometer showed an excellent ability to enter live mammalian cells in a short incubation period (10 min), a high sensitivity to temperature variations in live cells (temperature resolution of 0.02–0.84 °C in the range 20–40 °C), and remarkable non‐cytotoxicity, which permitted ordinary cell proliferation and even differentiation of primary cultured cells.     

Tandem five membered-ring selective Prins reaction and Friedel–Crafts reaction

A tandem reaction consisting of five membered-ring selective Prins cyclization and subsequent Friedel–Crafts cyclization was developed. The reactions of phenyl homoallylic alcohol 3 and benzaldehyde derivatives 6 afforded tetrahydroindenofurans 7 or pentacyclic products 8, depending upon the quantity of 6. Also homoallylic alcohol 12 having an alkyne–cobalt moiety reacted with 6 to give rise to tetrahydroindenofurans 13 in good yields.     

One-electron reduction of kinetically stabilized dipnictenes: synthesis of dipnictene anion radicals

The redox behavior of kinetically stabilized dipnictenes, BbtE=EBbt [E = P, Sb, Bi; Bbt = 2,6-bis[bis(trimethylsilyl)methyl]-4-[tris(trimethylsilyl)methyl]phenyl], was systematically disclosed using cyclic voltammetry and theoretical calculations. It was found that they showed reversible one-electron redox couples in the reduction region. The anion radical species of the Bbt-substituted diphosphene and distibene were successfully synthesized by the reduction of the corresponding neutral dipnictenes (BbtP=PBbt and BbtSb=SbBbt). Their structures were reasonably characterized by ESR, UV-vis, and Raman spectroscopy, and the distibene anion radical was structurally characterized by X-ray crystallographic analysis.     

Synthesis of [2]rotaxanes by the catalytic reactions of a macrocyclic copper complex

We synthesized [2]rotaxanes by the reactions catalyzed by a macrocyclic Cu(I)-phenanthroline complex. The catalytic site was located inside the ring component so that the rotaxane could be selectively formed. A C-S bond-forming reaction and oxidative dimerization of alkyne was utilized for the efficient synthesis of a new series of [2]rotaxanes. [reaction: see text]     

Formation of n-alkyl-n(1-hydroperoxyalkyl)nitrosamines from n-alkyl-n-(1-acetoxyalkyl)nitrosamines

N-alkyl-N-(1-hydroperoxyalkyl)nitrosamines were prepared by treatment of the corresponding 1-acetoxyalkyl nitrosamines with hydrogen peroxide in acetic acid through an acid-catalyzed nucleophilic substitution.     

Construction of Pt complex within Zr-based MOF and its application for hydrogen production under visible-light irradiation

The present article deals with Pt complex construction within Zr-based MOF having bipyridine units in the framework (Zr-MOF-bpy-PtCl₂) and its photocatalytic activity for hydrogen production under visible-light irradiation (λ > 420 nm). Zr-MOF-bpy-PtCl₂ is prepared by the construction of a Zr-based MOF using 2,2′-bipyridine-5,5′-dicarboxylic acid (Zr-MOF-bpy), and subsequent complexation reaction with K₂PtCl₄. XRD and N₂ adsorption–desorption measurements have revealed that both Zr-MOF-bpy and Zr-MOF-bpy-PtCl₂ have a UiO-type structure. From the results of UV–Vis and XAFS measurements, the incorporated Pt species has been proven to be in square planar geometry involving two N atoms and two Cl atoms as a result of the Pt coordination with bipyridine units in the framework. Zr-MOF-bpy-PtCl₂ has been employed for a hydrogen production reaction from water containing a sacrificial electron donor under visible-light irradiation (λ > 420 nm). Zr-MOF-bpy-PtCl₂ realizes steady hydrogen production, and the amount of evolved hydrogen reaches 8.3 μmol after the 9 h reaction period, while Zr-MOF-bpy exhibits no photocatalytic activity under the same conditions. It has also been found that the activity of Zr-MOF-bpy-PtCl₂ is superior to that of the corresponding homogeneous complex analogue (bpy)PtCl₂.     

A parallelized integral-direct second-order Møller–Plesset perturbation theory method with a fragment molecular orbital scheme

We propose a parallelized integral-direct algorithm of the second-order Møller–Plesset perturbation theory (MP2) as a size-consistent correlated method. The algorithm is a modification of the recipe by Mochizuki et al. [(1996) Theor Chim Acta 93:211]. There is no need to communicate the bulky data of integrals across worker processes, keeping the formal fifth-power dependence on the number of basis functions. A multiple integral screening procedure is incorporated to reduce the operation costs effectively. An approximate MP2 density matrix can also be directly calculated through the integral contraction with orbital energies. We implement the MP2 code by accepting Kitauras fragment molecular orbital (FMO) scheme as in the program ABINIT-MP developed by Nakano et al. [(2002) Chem Phys Lett 351:475]. The error in the FMO–MP2 energies is found to be within the order of the chemical accuracy. Timing and parallel acceleration results are shown for test molecules.