A new DMAP-catalyzed and microwave-assisted approach for introducing heteroarylamino substituents at position-4 of the quinazoline ring

We report herein a new methodology for synthesizing quinazoline derivatives bearing a heteroarylamino moiety at position-4 of the quinazoline ring. As an alternative to the Buchwald–Hartwig cross-coupling reaction, which appears, until now, as the only efficient way to react 4-chloroquinazolines with numerous amino nitrogen-containing heterocycles displaying poor nucleophilicity, we developed a DMAP-catalyzed reaction involving microwave irradiation. Optimization of the reaction conditions led to the use of 30 mol % of DMAP in toluene, using a monomode microwave reactor and sealed vials. Moreover, the S_NAr reaction intermediate salt was isolated and fully characterized. Finally, the procedure was extended to two different 2-substituted-quinazoline series and also to various anilines, demonstrating that this approach was a general efficient way to access to such 4-substituted quinazoline scaffolds of high pharmaceutical interest.     

Controlled/living radical polymerization of isoprene and butadiene in emulsion

A process for RAFT-controlled radical polymerization in emulsion [36] has been applied to the polymerizations of isoprene and of butadiene in emulsion systems, with the goal of producing latex particles containing block copolymers of acrylic acid (stabilizer and starting polymer), styrene (second polymer) and isoprene or butadiene (third polymer). The microstructure of the polymer chains was examined using dual-detection size-exclusion chromatography, and the nanostructure of the materials was investigated by differential scanning calorimetry and solid-state nuclear magnetic resonance. Reactions were always slow (although faster than the corresponding processes in solution), and exhibited limited reinitiation by isoprene when in emulsion. The materials containing isoprene exhibit a nanostructure with a phase separation into high-T_g polystyrene-rich domains and low-T_g polyisoprene-rich domains, revealed by DSC and NMR. This has the potential to lead to barrier materials with novel physical properties.     

Programmable Polymer‐Based Supramolecular Temperature Sensor with a Memory Function

A new class of polymeric thermometers with a memory function is reported that is based on the supramolecular host–guest interactions of poly(N‐isopropylacrylamide) (PNIPAM) with side‐chain naphthalene guest moieties and the tetracationic macrocycle cyclobis(paraquat‐p‐phenylene) (CBPQT⁴⁺) as the host. This supramolecular thermometer exhibits a memory function for the thermal history of the solution, which arises from the large hysteresis of the thermoresponsive LCST phase transition (LCST=lower critical solution temperature). This hysteresis is based on the formation of a metastable soluble state that consists of the PNIPAM–CBPQT⁴⁺ host–guest complex. When heated above the transition temperature, the polymer collapses, and the host–guest interactions are disrupted, making the polymer more hydrophobic and less soluble in water. Aside from providing fundamental insights into the kinetic control of supramolecular assemblies, the developed thermometer with a memory function might find use in applications spanning the physical and biological sciences.     

Easy and efficient selenocyanation of imidazoheterocycles using triselenodicyanide

The regioselective selenocyanation of imidazoheterocycles using triselenodicyanide at room temperature is reported. The electrophilic aromatic substitution of a broad range of substrates is promoted by the triselenodicyanide obtained by oxidative coupling of malononitrile and selenium dioxide, under an air atmosphere. The major advantages of the presented method are an easy set-up, excellent yields, short reaction times, use of odorless and inexpensive reagents and easy purification of the final products.     

Synthesis of partially benzylated arabinofuranosides,NMR analysis,and application to oligosaccharide synthesis

The preparation and NMR analysis of 2,3-di-O-benzyl arabinofuranosides have been described. In DMSO-d₆, the sugar adopts a conformation in which the hydroxyl groups are in an equatorial position; the equilibrium composition is determined by steric factors. In CDCl₃, the sugar adopts a conformation in which the intramolecular hydrogen bonding plays an important role in determining the equilibrium composition. The use of 2,3-di-O-benzyl arabinose in the synthesis of oligoarabinofuranosides enabled the synthesis of α- or β-linked furanosides.     

Diversity-orientated synthesis of 3,5-bis(arylamino)pyrazoles

The synthesis of differentially-substituted 3,5-bis(arylamino)pyrazoles has not yet been documented. During our investigation, we managed to develop a novel, entirely combinatorial synthesis of 3,5-bis(arylamino)pyrazoles relying on a simple one-pot two-step operation.     

Iron-catalyzed selective reduction of nitro compounds to amines

An efficient reduction of the nitro group with a catalytic amount of Fe(acac)₃ and TMDS in THF at 60 °C affording the corresponding amine is described.     

Influence of the Metal Ion on the Two‐Photon Absorption Properties of Lanthanide Complexes Including Near‐IR Emitters

The synthesis of tris(2‐thenoyltrifluoroacetonate)lanthanide(III) complexes featuring a diethylaminostyryl‐2,2′‐bipyridine coligand was achieved for lanthanum; the near‐infrared (NIR) emitters neodymium, erbium, and ytterbium; and the transition‐metal yttrium. The photophysical properties were thoroughly studied, and it was demonstrated that the conjugated bipyridine ligand acts as a good antenna for the sensitization of the NIR emitters. The two‐photon absorption (TPA) properties of all five complexes were investigated by using both two‐photon excited fluorescence and the Z‐scan method. We demonstrate that the nature of the rare earth ion has almost no influence on the TPA properties centered on the conjugated bipyridyl ligand. Finally, we show that Yb^III is sensitized by a two‐photon antenna effect, and that Nd^III is mostly sensitized by a one‐photon process involving direct excitation of forbidden f–f transitions.