Recent advance: Sulfur ylides in organic synthesis

Sulfur ylides are versatile structures that display various characteristics and participate in a myriad of reactions to produce simple, effective, and sometimes stereoselective reactions toward synthesizing sulfur-containing compounds. Nonetheless, their fulfillment tremendous developments have been made in this field in the past few decades. In this comprehensive review, luminosity is illuminated on the application of sulfur ylides involved in various domino, cascade annulation reactions, and carbene trapping reagents with chameleonic reactivity. In the past numerous decennary, chemists have used sulfur ylides in solvent-dependent, rhodium catalyzed, dealkylative intercepted, photochemical reaction, halotrifluoromethylation, benzannulation, amidation various name reactions such as Mizoroki–Heck, Suzuki–Miyaura, and Sommelet–Hauser rearrangements. Moreover, other prime applications include metal catalysis, epoxidation of carbonyl compounds, acylmethylation, cyclomerization, oxidation, and insertion reactions. Additionally, some sulfur ylides are extremely useful structures that play a major role in the synthesis of various medicinally active heterocycles structural motifs. This review article discusses all these reactions, their proposed mechanisms, and their application in the current scenario, at length. This tutorial review concludes by providing a future outlook on the investigation into sulfur ylides and various other compounds synthesized using it have great potential to be used in industries, laboratories, pharmaceutical companies, drug production, clinical use, medicinal chemistry, and agrochemical purposes.     

Theoretical Calculations and Experimental Verification of the Antibacterial Potential of Some Monocyclic β-Lactams Containing Two Synergetic Buried Antibacterial Pharmacophore Sites

A new series of N-thiazole, 3-phenyl, 4-substituted phenyl azetidine-2-ones 4(a–h) have been synthesized in good yields starting from 2-aminothiazole 1. In the first step, then Schiff's bases 3(a–h) are prepared by the condensation of 2-aminothiazole 1 with different aryl aldehydes 2(a–h). Finally, monocyclic β-lactams, i.e. substituted azetidinones 4(a–h), were the products formed using three different methods by the dehydrative cyclocondensation of 3(a–h) with phenyl acetyl chloride in dioxane, phenyl acetic acid–thionyl chloride in dichloromethane and phenyl acetic acid–phosphorus oxychloride in dichloromethane in the presence of triethylamine. We found that latter method is the best as compared with the former two methods. The synthesized molecules 4(a–h) were screened for their antibacterial activity against four microorganisms: Staphylococcus aureus (Gram positive), Pseudomonas vulgaris (Gram positive), Pseudomonas aeruginosa (Gram negative), and Escherichia coli (Gram negative). Their antibacterial activities are reported, and on the basis of the screening data available, attempt is also made to elucidate the structure–activity relationship.

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.     

Quantifying Forces Mediated by Integral Tight Junction Proteins in Cell–Cell Adhesion

Cellular adhesion and barriers formed by intercellular adhesion proteins [tight junctions (occludin and claudins) and adherens junction (E-cadherin)] are important in maintaining tissue homeostasis. However, disruption of these junction proteins is associated with diseases in the organ systems such as multiple sclerosis, diarrhea, asthma, and gastro-intestinal tract carcinomas among others. In this paper, the separation force needed to separate two cells expressing some of these proteins was measured using the dual micropipette assay. Results show that L-fibroblasts transfected with claudin-1 and claudin-2 exhibit higher separation force (~2.8 nN and 2.3 nN, respectively) as compared to control cells or cells transfected with occludin (~1 nN). Furthermore, the separation force was not affected on addition of calcium chelating agent (ethylene diamine tetra acetic acid, EDTA). The separation force was, however, significantly decreased on treating cells with the actin disrupting agent Cytochalasin-D. These results show that the dual micropipette assay is a simple and useful experimental technique for quantifying cell–cell adhesion.     

Synthesis of New 1, 10‐Phenanthroline Analogs as Potent Antimicrobial Agents Using Montmorillonite K‐10 as Catalyst

A series of new 1, 10‐phenanthroline derivatives are synthesized by the four‐component domino reactions of 8‐hydroxy quinoline, aromatic aldehydes, methyl/ethyl acetoacetate and ammonium acetate in the presence of zeolite (montmorillonite K‐10) using both conventional and microwave methods. Most of the new compounds possessed moderate to significant anti‐bacterial and anti‐fungal activities.     

Carbon-carbon bond forming reactions via Pd-catalyzed detellurative homocoupling of diorganyl tellurides

A simple and highly efficient method for the constructions of Csp-Csp, Csp²-Csp² and Csp³-Csp³ bonds is reported. The symmetrical diaryl tellurides undergo detellurative homocouplings to afford symmetrical biaryl products. The reactions are carried out at ambient temperature using PdCl₂ as a catalyst in the presence of Ag₂O and Na₂CO₃. Similarly, the detellurative homocouplings of dibenzyl telluride and bis(phenylethynyl)telluride give bibenzyl and the conjugated diyne, respectively.     

Mononuclear manganese(III) aquo complexes. Crystal and molecular structures of [Mn(phen)(OH2)Cl3] and [Mn(acac)2-(OH2)2]ClO4·2H2O (acacH = acetylacetone,phen = 1,10-phenanthroline)

Summary The crystal and molecular structures of [Mn(phen)-(OH₂)Cl₃] (1) and [Mn(acac)₂(OH₂)₂]ClO₄·2H₂O (2) were determined. A comparison is made of the Jahn-Teller distortion in these compounds with those observed in other manganese(III) complexes with monodentate axial ligands.     

Greener route for the synthesis of photo- and thermochromic spiropyrans using a highly efficient,reusable, and biocompatible choline hydroxide in an aqueous medium

Here, we report the synthesis of photo- and thermochromic spiropyrans promoted by a highly efficient, biocompatible, and reusable choline hydroxide (ChOH) in greener solvent water. This procedure provides several advantages such as simple workup, mild reaction conditions, short reaction time, and high yields of the products. Furthermore, the ChOH could be reused at least five times without significantly losing its catalytic activity. The structures of the synthesized spiropyran derivatives were confirmed by several characterization methods such as ¹H NMR, ¹³C NMR, and mass spectra.     

New electrode-barrier structures for high density ferroelectric memories

In this paper, two electrode-barrier structures based on Pt-Rh and Pt-Ir alloys and their oxides are proposed for high-density ferroelectric memory applications. These electrode-barriers are multi-layered, comprising a diffusion barrier (PtRhOx or PtIrOx), metal alloy (PtRh or PtIr) and another PtRhOx or PtIrOx layer for fatigue reduction in the case of PZT capacitors. Both lead zirconate titanate (PZT) and strontium bismuth tantalate (SBT) capacitors based on the electrode-barriers were used in the present study. The electrode-barrier structure acts as a conducting electrode as well as an excellent diffusion barrier for lead, bismuth, oxygen and silicon. The PZT test capacitors fabricated on these electrode-barriers showed excellent fatigue resistance with other ferroelectric properties being similar to those on Pt. Also, these electrode-barriers are stable, and remain conductive even up to the processing temperatures of SBT (750 °C). This makes direct integration of both PZT and SBT capacitors on to a poly-Si plug attainable. In addition, the conducting electrode-barrier structures can be deposited in situ, directly over n+polycrystalline Si, thereby significantly improving the density of the device. Received: 11 July 2000 / Accepted: 13 July 2000 / Published online: 30 November 2000     

Ultrasound‐Assisted One‐pot Synthesis of Bis‐azetidinones in the Presence of Zeolite

Sonochemical method is an innovative task for the sustainable chemical research industry. In this work, an attempt was made to synthesize bis‐azetidin‐2‐ones ( 2a , 2b , 2c , 2d , 2e , 2f , 2g , 2h , 2i , 2j ) by Staudinger reaction ([2 + 2] ketene‐imine cycloaddition reaction) in the presence of zeolite by using both conventional and under ultrasound irradiation. The synthesized compounds have been elucidated on the basis of their elemental analysis and spectral data (IR, ¹H NMR, ¹³C NMR, and mass spectra) to evaluate its performance obtained under ultrasonic waves. It was observed that complete conversion to azetidin‐2‐ones occurred in 1–2 h by sonochemical method and in 15–46 h by conventional method. Finally, it has been observed that 2‐azetidinones synthesis using sonochemical method is an energy efficient and environmentally friendly technique over the conventional method.