Aspartic-acid-loaded starch-functionalized Mn–Fe–Ca ferrite magnetic nanoparticles as novel green heterogeneous nanomagnetic catalyst for solvent-free synthesis of dihydropyrimidine derivatives as potent antibacterial agents

Research on Chemical Intermediates - Mn0.5Fe0.25Ca0.25Fe2O4@starch@aspartic acid magnetic nanoparticles (MNPs) as a new green nanocatalyst were designed and synthesized by a coprecipitation...     

Saccharide Recognition by a Three-Arm-Shaped Host Having Preorganized Three-Dimensional Hydrogen-Bonding Sites

Generally, cage-shaped hosts for saccharides can bind strongly to guest molecules because of the three-dimensional preorganized hydrogen-bonding sites. However, the preparation of cage molecules is often difficult because of the low yield of the macrocyclization step. Here, we report a three-arm-shaped molecule possessing pyridine-acetylene-phenol units as a new kind of host having a preorganized three-dimensional hydrogen-bonding site. This three-arm-shaped host was readily prepared compared to a cage-shaped analogue. This host associated with lipophilic glycosides to form chiral complexes, and the association constants were sufficiently high as to be comparable to those of the cage-shaped analogue. Furthermore, this host extracted native monosaccharides into a lipophilic solvent.     

Reactions of Selenobenzophenones with Olefins

Reactions of selenobenzophenones with methyl propiolate afforded two types of cycloadducts regioselectively. The reaction with tetracyanoethylene gave selenophene derivatives. Mechanisms of these reactions were discussed.     

An Efficient Synthesis of New Substituted Spiro Pyrazolethieno,Pyrimidinethieno, and Benzodiazepinethieno Pyridazine Derivatives with Biological Activities

3-Ethyl 2-amino-4-methyl-5-phenyl thiophene carboxylate 1 was used as a starting material to synthesize 2a,b via coupling with malononitrile or acetyl acetone, respectively. When heated, under reflux in sodium ethoxide solution, 2a,b give 3a,b. On the other hand, when compounds 3a,b were heated under reflux in ethanol with hydrazine hydrate, thiourea, or 1,1-phenylenediamine hydrochloride and a catalytic amount of piperidine 4a,b, 5a,b and 6a,b, were produced, respectively. The new compounds were tested for their antimicrobial activity. Compounds 2a–6b showed antibacterial activities, and 2a,2b and 4b showed antifungal activities.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Reaction of 2-Thioxo-4-Thiazolidinones Toward Lawesson's Reagent,Phosphorus Pentasulfide,Dialkylaminophosphines, and Phosphorus Ylides

Abstract

2-Thioxo—3-allyl-4-thiazolidinone 1a reacts with Lawesson's reagent (LR, 2) to give the ethylenic product 5 through a coupling reaction along with the dithioxo compound 6. Coupling reaction products of types 8 and 9 are also produced upon reacting thiazolidinones 1 and with the appropriate tris(diallkylamino) phosphine reagent (3 a,b). Reaction of the thiazolidinone 1a with the ylidenetriphenylphosphorane reagents 4 a–c proceeds according to the Wittig mechanism yielding ethylenes 10a–c, respectively. Structural elucidations for the new products were based upon compatible analytical and spectroscopic measurements as well a confirmatory single crystal X-ray structure for 5.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the related elements to view the free supplemental file.     

Synthesis of Star-Shaped Polymers via Coordination of Bipyridyl-Terminated Polyoxyethylene with Metal Ions

Abstract

This paper describes the synthesis of various star-shaped polymers by means of complexation of bipyridyl-terminated polyoxyethylene with Ru(II) ion. Three kinds of bipyridyl-terminated polyoxyethylenes of different molecular weights were prepared from the corresponding polyoxyethylene monomethyl ethers with narrow molecular weight distributions. Bipyridyl was found to be introduced quantitatively at the end of the polymers based on the results of UV spectra. The formation of a star-shaped polymer was carried out by the reaction of RuCl₃ with three equivalents of bipyridyl-terminated polyoxyethylene. The UV spectrum of the star-shaped polymer obtained supported the formation of a typical Ru(II) tris(bipyridyl) complex. From the results of GPC, the star-shaped polymer obtained had a higher molecular weight than the pre-polymer and showed a narrow molecular weight distribution. In the case of a Ni(II) or a Co(II) complex, however, the star-shaped polymer was found to be dissociated into three linear prepolymers under the conditions of GPC measurement.     

Supramolecular chemosensor for selective detection of iron in aqueous medium

We have successfully developed a ‘turn-on’ colorimetric chemosensor for Fe³⁺ based on 1,10-phenanthroline. An amide derivative of 1,10-phenanthroline 4 was developed for the selective recognition of Fe³⁺ over Co²⁺, Cr³⁺, Cu²⁺, Mn²⁺, Ni²⁺, Ag⁺ and Zn²⁺ and could measure Fe³⁺ concentration in the range of 15–210 μM by UV–vis spectroscopy. Moreover, the addition of Fe³⁺ to a colourless solution of 4 turned its colour to light pink, indicating that 4 is capable of detecting Fe³⁺ by the naked eye. Compound 4 exhibits a major absorption band centred at 268 which shifted to 278 nm after addition of Fe³⁺, and a shoulder band around 514 nm was also observed. The complexation of Fe³⁺ with 4 was analysed at a different pH and favourable binding was observed at pH 6.2.     

Recent advances in synthesis of 2-pyridones: a key heterocycle is revisited

Owing to the versatile applications in different areas including biology, natural compounds, dyes, and fluorescent materials, the synthesis of 2-pyridone compounds is an important research field and has attracted a great deal of attention. In this review, 2-pyridones new synthetic methods are classified to tree classes including reactions based on pyridine rings, cyclization, and cycloaddition reactions.