A Selective G-Quadruplex DNA-Stabilizing Ligand Based on a Cyclic Naphthalene Diimide Derivative

A cyclic naphthalene diimide (cyclic NDI, 1), carrying a benzene moiety as linker chain, was synthesized and its interaction with G-quadruplex DNAs of a-core and a-coreTT as a human telomeric DNA, c-kit and c-myc as DNA sequence at promoter region, or thrombin-binding aptamer (TBA) studied based on UV-VIS and circular dichroism (CD) spectroscopic techniques, thermal melting temperature measurement, and FRET-melting assay. The circular dichroism spectra showed that 1 induced the formation of different types of G-quadruplex DNA structure. Compound 1 bound to these G-quadruplexes with affinities in the range of 106–107 M−1 order and a 2:1 stoichiometry. Compound 1 showed 270-fold higher selectivity for a-core than dsDNA with a preferable a-core binding than a-coreTT, c-kit, c-myc and TBA in the presence of K+, which is supported by thermal melting studies. The FRET-melting assay also showed that 1 bound preferentially to human telomeric DNA. Compound 1 showed potent inhibition against telomerase activity with an IC50 value of 0.9 μM and preferable binding to G-quadruplexes DNA than our previously published cyclic NDI derivative 3 carrying a benzene moiety as longer linker chain

Pd-catalyzed Cyclization of Terminal Alkynes using Diazonaphthoquinones: Synthesis of Naphtho[1,2-b]furans

Naphtho[1,2-b] furans were synthesized via a Pd-catalyzed reaction of diazonaphthoquinones and terminal alkynes in the presence of CuI and diisopropylamine. This method was then successfully applied to the synthesis of natural product, furomollugin

Unprecedented formation of η4-(vinylketene)iron complexes from η4-(diene)iron complexes and aromatic compounds in the presence of a Lewis acid

A novel and unprecedented formation of η4-(vinylketene)iron complexes from η4-(diene)iron complexes is described herein. Treatment of η4-(diene)iron complexes with a Lewis acid such as GaCl3 or AlCl3 in the presence of aromatic compounds under a CO atmosphere affords η4-(vinylketene)iron complexes via electrophilic aromatic substitution

Selective Transesterification of 2,2,2-Trifluoroethyl Phosphates: Synthesis of Mixed Unsymmetrical Phosphates

A selective transesterification starting with tris(2,2,2-trifluoroethyl) phosphate has been developed. This method involves a three-step substitution for 2,2,2-trifluoroethoxy groups and enables the facile synthesis of mixed unsymmetric phosphate triesters from three different alcohols. The substitution of the trifluoroethoxy group at the phosphorus proceeds selectively in the presence of DBU or lithium alkoxides. This method can be applied for the preparation of phospholipids

Thermodynamics and Kinetic Studies in the Binding Interaction of Cyclic Naphthalene Diimide Derivatives with Double Stranded DNAs

Previously, we reported our investigations of the interaction between a cyclic naphthalene diimide derivative (cNDI 1) and double stranded DNA (dsDNA) (Bioorg. Med. Chem.2014, 22, 2593). Here, we report the synthesis of the novel cNDI 2, which has shorter linker chains than cNDI 1. We performed comparative investigations of the interactions of both cNDI 1 and cNDI 2 with different types of dsDNA, including analysis of their thermodynamics and kinetics. Interactions between the cNDIs and calf thymus DNA (CT-DNA), poly[d(A-T)]2, or poly[d(G-C)]2 were explored by physicochemical and biochemical methods, including UV–Vis spectroscopy, circular dichroism (CD) spectroscopy, stopped-flow kinetics, and a topoisomerase I assay. Upon addition of cNDIs to CT-DNA, the existence of an induced CD signal at approximately the wavelength of the naphthalene diimide chromophore and unwinding of the DNA duplex, as detected by the topoisomerase I assay, revealed that cNDIs bound to the DNA duplex. As indicated by the steric constraint in the formation of the complex, bis-threading intercalation was the more favorable binding mode. UV–Vis spectroscopic titration of the cNDIs with DNA duplexes showed affinities on the order of 105–106 M−1, with a stoichiometry of one cNDI molecule per four DNA base pairs. Thermodynamic parameters (ΔG, ΔH, and ΔS) based on the van’t Hoff equation indicated that exothermic and entropy-dependent hydrophobic interactions played a major role in the reaction. Stopped-flow association and dissociation analysis showed that cNDI interactions with poly[d(G-C)]2 were more stable and had a slower dissociation rate than their interactions with poly[d(A-T)]2 and CT-DNA. Measurement of ionic strength indicated that electrostatic attraction is also an important component of the interaction between cNDIs and CT-DNA. Because of its longer linker chain, cNDI 1 showed higher binding selectivity, a more entropically favorable interaction, and much slower dissociation from dsDNA than cNDI 2

Molecular Structure and Crystal Packing of n-Type Semiconducting Material 3\u27,3\u27-(1,4-Phenylene) bis {2\u27-(4-trifluoromethyl) phenyl} acrylonitrile

The exact molecular structure and the crystal packing of the n-type semiconducting material 3′,3′-(1,4-phenylene)bis{2′-(4-trifluoromethyl)phenyl}acrylonitrile was determined by a single crystal X-ray diffraction with twin treatment technique. The air-stable product was crystallized from dichloromethane-hexane mixed solution. The solid-state structure is the example of a typical π-π stacking with side intermolecular CN–H short contact networks

PdBr2‐Catalyzed Acetal Formation of Carbonyl Compounds Using Diazophenanthrenequinone: Utility of 9,10‐Phenanthrenedioxyacetal

We developed a new acetalization method of ketones and aldehydes under non-acidic conditions using diazophenanthrenequinone and PdBr2. The formed acetals that have a phenanthrene skeleton withstand under mild acidic conditions. Removal of acetals was successfully proceeded under strong acidic or oxidation conditions using aqueous ceric ammonium nitrate (CAN) to afford corresponding ketones and aldehydes

Direct Azidation of Phenols

Direct azidation of phenols was developed. By treating chloroimidazolinium chloride 1b and sodium azide with phenol in the presence of a secondary amine in methoxyethanol, ortho-azidation of phenol was achieved

Pyrrole Formation via Reactivity of η4-(Vinylketenimine)iron Complexes with Electron-Deficient Alkynes

When electron-deficient alkynes reacted with η4-(vinylketenimine)iron complexes, pyrroles were produced. Pyrrole formation involved the [2 + 3] cycloaddition of alkyne to the ketenimine moiety, migration of the vinyl group, and decomplexation. Either alkynes bearing two electron-withdrawing groups, or terminal alkynes with an electron-withdrawing group reacted to generate pyrroles

A Steady Operation of n-Type Organic Thin-Film Transistors with Cyano-Substituted Distyrylbenzene Derivative

A novel n-type organic semiconductor, cyano-substituted distyrylbenzene derivative, 1,4-bis2-[4-(trifluoromethyl)phenyl]acrylonitorilebenzene, was synthesized by Knoevenagel condensation with aldehyde and acetonitrile derivatives. Fabricated thin-film transistors (TFTs) exhibited high electron field-effect mobility of 10-2?10-1 cm2 V-1 s-1, on/off current ratio of 6×105. Hysteresis-free n-type transport characteristics observed in this device promises a steady operation of organic logic circuit. Almost same TFT characteristic was observed even after 1 month storage in ambient condition. The findings indicate that the material has a good resistance to atmospheric oxidants