Synthesis of Novel 6‐Mercapto‐12‐phenethyl‐quinazolino[3,4‐a]quinazolinones

Novel 6‐mercapto‐12‐phenethyl‐quinazolino[3,4‐a]quinazolinone derivatives were synthesized through a user‐friendly five‐step reaction starting from isatoic anhydride. All products were characterized by IR, ¹H‐NMR, ¹³C‐NMR spectroscopy, and chemical analysis. All of them were evaluated for their in vitro cytotoxic activity against two cell lines namely MOLT‐4 (human lymphoblastic leukemia) and MCF‐7 (human breast adenocarcinoma).     

Resorcinarene bis-crown silver complexes and their application as antibacterial Langmuir-Blodgett films

Silver complexes of a cation binding supramolecular host, resorcinarene bis-crown (CNBC5) with propyl, nonyl, decyl and undecyl alkyl chains were investigated by NMR titration, picrate extraction and single crystal X-ray diffraction. Binding studies showed that both 1 : 1 and 1 : 2 (host-Ag(+)) complexes are present in solution with only a slight effect of the lower rim alkyl chain length on the binding constants (log K 4.0-4.2 for 1 : 2 complexes). Solid state complexes of the resorcinarene bis-crowns bearing either C(3) or C(11) chains were obtained. Single crystal X-ray analyses showed that both derivatives bind silver ions by metal-arene and Ag···O coordination from the crown ether bridges and from the solvent, and pack in layered or bilayered fashion. Furthermore, the amphiphilic nature of C11BC5 was demonstrated using the Langmuir balance technique. Langmuir-Blodgett films of the amphiphilic C11BC5-Ag complex were transferred onto a substrate and shown to possess antibacterial activity against E. coli.     

Recent Progress on Biological Activity of Amaryllidaceae and Further Isoquinoline Alkaloids in Connection with Alzheimer’s Disease

Alzheimer’s disease (AD) is a progressive age-related neurodegenerative disease recognized as the most common form of dementia among elderly people. Due to the fact that the exact pathogenesis of AD still remains to be fully elucidated, the treatment is only symptomatic and available drugs are not able to modify AD progression. Considering the increase in life expectancy worldwide, AD rates are predicted to increase enormously, and thus the search for new AD drugs is urgently needed. Due to their complex nitrogen-containing structures, alkaloids are considered to be promising candidates for use in the treatment of AD. Since the introduction of galanthamine as an antidementia drug in 2001, Amaryllidaceae alkaloids (AAs) and further isoquinoline alkaloids (IAs) have been one of the most studied groups of alkaloids. In the last few years, several compounds of new structure types have been isolated and evaluated for their biological activity connected with AD. The present review aims to comprehensively summarize recent progress on AAs and IAs since 2010 up to June 2021 as potential drugs for the treatment of AD.     

Hybrid-Density Functional Theory Study and Natural Bond Orbital Interpretation of the Conformational Behavior of 1,3-Dioxanyl, 1,3-Dithianyl,and 1,3-Diselenanyl Carbanions

Abstract

The effective factors on the conformational properties of 1,3-dioxanyl (1), -dithianyl (2), and -diselenanyl (3) carbanions have been investigated by means of the hybrid-density functional theory (DFT) (B3LYP/6-311+G**)-based method and natural bond orbital (NBO) interpretation. The results obtained showed that the axial conformation (i.e., the axial H atom attached to C₂) of carbanion 1 is more stable than its equatorial conformation. Contrary to the carbanion 1, the equatorial conformations of carbanions 2 and 3 are more stable than their corresponding axial conformations. The instability of the axial conformations of carbanions 1–3 increases from carbanion 1 to carbanion 2 but decreases from carbanion 2 to carbanion 3. The NBO analysis showed that the anomeric effect (AE) associated with the electron delocalization increases from carbanion 1 to carbanion 2, but decreases from carbanion 2 to carbanion 3. The calculated total dipole moment values of the axial conformations of carbanions 1–3 are greater than those of their corresponding equatorial conformations, but the calculated total dipole moment difference values between the axial and equatorial conformations decreases from carbanion 1 to carbanion 3. Consequently, the AE associated with the electron delocalization, but not the total dipole moment changes (i.e., Δμ_ax–eq), thus explaining the total energy differences between the axial and equatorial conformations of carbanions 1–3. The correlations between the AE, dipole moments, ΔG_ax–eq, structural parameters, and conformational behaviors of carbanions 1–3 have been investigated.

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.     

Sulfuric acid {[3-(3-silicapropyl)sulfanyl]propyl}ester a recyclable catalyst for the synthesis of 2-aryl- 1-arylmethyl- 1H- 1,3-benzimidazole derivatives

A highly selective synthesis of 2-aryl-1-arylmethyl-1H-1,3-benzimidazoles from the reaction of o-phenylenediamine and aromatic aldehydes in the presence of sulfuric acid {[3-(3-silicapropyl)sulfanyl]propyl}ester(SASPSPE) in water and at 80℃in good to excellent yields.