A new and efficient method for conjugate addition of trialkylphosphites to 3-acylsubstituted coumarins

A new and efficient conjugate addition of trialkylphosphites to 3-ω-bromoacetylcoumarin 1 catalysed by p-toluenesulfonic acid (TsOH) has been studied. Under the same conditions, an enolphosphate gave the corresponding esters of 3-acetyl-4-phosphono-2-oxochromans in high yields. The use of TsOH in the reaction of 3-acetyl-, 3-benzoyl-, and 3-ethoxycarbonyl coumarins led mainly to 1,4-addition products—the corresponding 3-acyl-4-dialkylphosphono-2-oxochromans—in very good yields.     

Highly efficient synthesis of chiral aminoalcohols and aminodiols with camphane skeleton

Methylidene substituted camphor was easily epoxidized to give bridgehead oxirane-substituted camphor in the form of two diastereoisomers, isolated in pure form. These were used in aminolysis reactions with different secondary amines leading to series of chiral aminoalcohols bearing a ketone functionality. The latter could be reduced by using LAH or DIBAL to a series of aminodiols. For the determination of the configuration of the newly formed stereogenic centre, advanced NMR experiments and X-ray crystallography were used. The new aminoalcohols and aminodiols were tested as pre-catalysts for the enantioselective addition of Et₂Zn to benzaldehyde showing moderate enantioselectivity.     

Approaches for ultrafast imaging of transient materials processes in the transmission electron microscope

The growing field of ultrafast materials science, aimed at exploring short-lived transient processes in materials on the microsecond to femtosecond timescales, has spawned the development of time-resolved, in situ techniques in electron microscopy capable of capturing these events. This article gives a brief overview of two principal approaches that have emerged in the past decade: the stroboscopic ultrafast electron microscope and the nanosecond-time-resolved single-shot instrument. The high time resolution is garnered through the use of advanced pulsed laser systems and a pump-probe experimental platforms using laser-driven photoemission processes to generate time-correlated electron probe pulses synchronized with laser-driven events in the specimen. Each technique has its advantages and limitations and thus is complementary in terms of the materials systems and processes that they can investigate. The stroboscopic approach can achieve atomic resolution and sub-picosecond time resolution for capturing transient events, though it is limited to highly repeatable (>10(6) cycles) materials processes, e.g., optically driven electronic phase transitions that must reset to the material's ground state within the repetition rate of the femtosecond laser. The single-shot approach can explore irreversible events in materials, but the spatial resolution is limited by electron source brightness and electron-electron interactions at nanosecond temporal resolutions and higher. The first part of the article will explain basic operating principles of the stroboscopic approach and briefly review recent applications of this technique. As the authors have pursued the development of the single-shot approach, the latter part of the review discusses its instrumentation design in detail and presents examples of materials science studies and the near-term instrumentation developments of this technique.     

Intramolecular-activation evidence for the unexpected Beckmann fragmentation of C(1)-substituted-7-bromonorbornane-2-ones

The competitive pathway timing for the previously described unexpected bromo-assisted Beckmann fragmentation of 7-anti-bromo-3,3-dimethyl-2-oxonorbornane-1-carboxamide has been investigated. It is concluded that this unusual process is activated by a synergic effect exerted by both the C(7)-anti-bromo and C(1)-aminocarbonyl groups. The effect consists in a specific intramolecular activation of the bromo-assistance by the bridgehead aminocarbonyl group.     

Efficient One‐Pot Friedel–Crafts Acylation of Benzene and its Derivatives with Unprotected Aminocarboxylic Acids in Polyphosphoric Acid

A number of aminobenzophenones have been synthesized by acylation of benzene and its derivatives with different 2‐,3‐,4‐aminobenzoic and 4‐aminophenylacetic acids in polyphosphoric acid via Friedel–Crafts reaction as compounds with expected antitumor activity.     

Anthracene-Derived Bis-Aminophosphonates: Crystal Structure,In Vitro Antitumor Activity,and Genotoxicity In Vivo

Abstract

The X-ray crystal structures of the anthracene-derived bis-aminophosphonates 4.4′-bis[N-methyl(diethoxyphosphonyl)-1-(9-anthryl)]diaminodiphenylmethane (1) and 1,3-bis

[N-methyl(diethoxyphosphonyl)-1-(9-anthryl)]diaminobenzene (3) are reported. The X-ray analyses demonstrated that both compounds crystallize in a centrosymmetric manner containing a meso-form (1) and a pair of enantiomers (3).

The cytotoxic potential, genotoxicity, and antiproliferative activity of bis-aminophosphonates 1 and bis[N-methyl(diethoxyphosphonyl)-1-(9-anthryl)]benzidine (2), as well as their subcellular distribution in a tumor cell culture system, are also discussed. Compounds 1 and 2 showed optimal antiproliferative activity to human tumor cells from colon carcinoma line HT-29. In vitro and in vivo safety testing revealed that the compounds exert lower toxicity to normal cells as compared with well-known anticancer and cytotoxic agents.

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

Electrotransport properties of ions in aqueous solutions of H<Subscript>2</Subscript>SeO<Subscript>4</Subscript> and Na<Subscript>2</Subscript>SeO<Subscript>4</Subscript>

Coefficients of self-diffusion, absolute speeds of movement of ions and the activation energy of electrical conductivity are found from the conductance measurements of aqueous solutions of selenic acid and sodium selenate at different concentrations in a temperature range of 288–318 K. Both the Stokes and effective radii of ions and their hydrate numbers at 298 K are calculated. The obtained results are interpreted in the frames of Samoilov theory on positive and negative hydration of ions.