Efficient Resolution of Some Monoprotected Derivatives of Corey Lactone

Racemic monoprotected at primary hydroxy group Corey lactones were resolved using (1S,2R,5R)-6,6-dimethyl-4-oxo-3-oxabicyclo-[3.1.0]hexan-2-ol as a chiral auxiliary reagent of hemiacylal chemotype.     

Plasma relativistic microwave noise amplifier with the inverse configuration

The results of numerically simulating a high-power plasma maser—the wideband microwave noise amplifier—are reported. The configuration and parameters of the device are chosen with a view to its possible future use for generating pulses with a duration of 3 ns and pulse frequency bandwidth of 0.3 to 2GHz. In the pulse-periodic mode, it is possible to generate radiation in a continuous range of 2 to 12GHz with an average pulse power of 20MWand pulse energy efficiency of 6%.     

Correction to: Aziridine-2-Carboxylic Acid Derivatives and Its Open-Ring Isomers as a Novel PDIA1 Inhibitors

Chemistry of Heterocyclic Compounds -     

Controlling the Surface Functionalization of Ultrasmall Gold Nanoparticles by Sequence-Defined Macromolecules

Ultrasmall gold nanoparticles (diameter about 2 nm) were surface-functionalized with cysteine-carrying precision macromolecules. These consisted of sequence-defined oligo(amidoamine)s (OAAs) with either two or six cysteine molecules for binding to the gold surface and either with or without a PEG chain (3400 Da). They were characterized by ¹H NMR spectroscopy, ¹H NMR diffusion-ordered spectroscopy (DOSY), small-angle X-ray scattering (SAXS), and high-resolution transmission electron microscopy. The number of precision macromolecules per nanoparticle was determined after fluorescent labeling by UV spectroscopy and also by quantitative ¹H NMR spectroscopy. Each nanoparticle carried between 40 and 100 OAA ligands, depending on the number of cysteine units per OAA. The footprint of each ligand was about 0.074 nm² per cysteine molecule. OAAs are well suited to stabilize ultrasmall gold nanoparticles by selective surface conjugation and can be used to selectively cover their surface. The presence of the PEG chain considerably increased the hydrodynamic diameter of both dissolved macromolecules and macromolecule-conjugated gold nanoparticles.     

Influence of pH on the binding of diphenylmethylenepiperidines by 5-HT2B receptors in rat stomach fundus

Cyproheptadine is one of the compounds exhibiting the highest activity at 5-HT2B receptors. In a previous work we analysed the relevance of the amino group in diphenylmethylenepiperidines (DPMP), which are open cyproheptadine analogues. Only compounds containing N-H or N-methyl motifs, showed significant 5-HT2B activity. Surprisingly, the corresponding quaternary ammonium salt demonstrated a total lack of activity. Therefore, the question arises whether protonation favours the interaction of these compounds with 5-HT2B receptors. Consequently, we studied the protonation influence (by varying the pH of the medium) on the antagonism of serotonin by some cyproheptadine analogues in rat stomach fundus. The main results were: 1) N-protonation increases the activity of DPMPs. 2) Alkaline pH facilitates the occurrence of a non-surmountable antagonism. 3) The contrast between the activity of protonated DPMPs and the lack of activity of the corresponding quaternary ammonium cation, suggests either that the latter is prevented from acting by steric hindrance, or that the mechanism by which protonation may increase the activity depends not only on the charge of the proton, but also on its ability to form hydrogen bonds.     

Synthesis of novel chromene scaffolds for adenosine receptors

A one-pot procedure was developed for the synthesis of novel 3-[amino(methoxy)methylene]-2-oxo-3,4-dihydro-2H-chromen-4-yl)-3-cyanoacetamides and chromeno[3,4-c]pyridine-1-carbonitriles from the reaction of 2-oxo-2H-chromene-3-carbonitriles and cyanoacetamides. These chromene derivatives were identified as new scaffolds for adenosine receptors and the hits 3a, 3c, 5a, and 5b were found.     

Relativistic Cherenkov plasma maser of microsecond pulse duration

Experiments with a Cherenkov plasma maser (CPM) driven by a high-current relativistic electron beam of microsecond pulse duration are described. The results obtained show that the principle of operation of the CPM makes it possible to avoid the problem of microwave pulse shortening, which is inherent to vacuum devices of relativistic high-current microwave electronics. A 800-ns microwave pulse with an energy of 21 J was obtained at a peak power level of 40 MW (the efficiency being 4%) in a broad (~100%) frequency band     

Polymerization of aniline in perfluorinated membranes under conditions of electrodiffusion of monomer and oxidizer

Journal of Solid State Electrochemistry - A series of composites based on the perfluorinated MF-4SK membrane and polyaniline was obtained under electrodiffusion of monomer and oxidizer. Aniline was...