Electrogenerated base-promoted synthesis and antimicrobial activity of 2-imino-1,3-thiazolidin-4-one derivatives

Electrogenerated cyanomethylanions obtained by reduction of dry acetonitrile at a steel grid cathode were used to promote the addition of ethyl bromoacetate to thiourea derivatives. The reaction yields the corresponding 2-imino-1,3-thiazolidin-4-one. The reaction pathway was discussed based on the kinetic and thermodynamic data obtained by computational methods. In addition, the biological activity of these new compounds was also investigated.     

Planar‐Chiral Cyclopentadienyl‐Ruthenium‐Catalyzed Regio‐ and Enantioselective Asymmetric Allylic Alkylation of Silyl Enolates under Unusually Mild Conditions

We report the asymmetric allylic alkylation of allylic chlorides with silyl enolates as a carbon nucleophile using a planar‐chiral cyclopentadienyl‐ruthenium (Cp′Ru) catalyst. The reaction proceeds under unusually mild conditions to give the desired branched products with complete regioselectivity and high enantioselectivity, and reactive functional groups, such as aldehyde, can be tolerated. In this reaction system, Cp′Ru plays an important role in activating both silyl enolate and allylic chloride.

     

Electrogenerated Chemiluminescence from a Phenyleneethynylene Derivative and its Ultrasensitive Immunosensing Application Using a Nanotubular Mesoporous Pt–Ag Alloy for Signal Amplification

Electrogenerated chemiluminescence (ECL) of a novel phenyleneethynylene derivatives [4,4’‐(2,5‐dimethoxy‐1,4‐phenylene)bis(ethyne‐2,1‐diyl) dibenzoic acid; P‐acid] possessing carboxylic acid groups at the para positions in aqueous solutions and its first immunosensing application are studied. Nanotubular mesoporous Pt–Ag alloy nanoparticles are first used to fabricate the ECL immunosensor as a signal amplification carrier. Absorption, photoluminescence, cyclic voltammetry, scanning electron microscopy, transmission electron microscopy, and electrochemical impedance spectroscopy are used as powerful tools to characterize P‐acid, Pt–Ag alloy nanoparticles, and the fabrication process of the immunosensor. P‐acid exhibits two ECL peaks at –1.07 (ECL‐1) and 0.64 (ECL‐2) V in air‐saturated pH 7.4, 0.1 M PBS containing 0.1 M KCl during the cyclic sweep between 1.51 and –2.67 V at 0.1 V s^?1; the ECL mechanism of these two ECL peaks is demonstrated. The electron‐transfer reaction between electrochemically oxidized P‐acid and tri‐n‐propylamine (TPrA) radical cation is also demonstrated to produce high ECL emissions and used to develop an ultrasensitive ECL immunosensor. In addition, a Pt–Ag alloy nanoparticles amplification carrier for protein ECL analysis is applied for improvement of the detection sensitivity. Thus, this ECL immunosensor exhibits high sensitivity, good reproducibility, rapid response, and long‐term stability.     

Electrochemically Induced Addition Reactions in the Absence of Solvent and Supporting Electrolyte

Solvent‐ and supporting electrolyte‐free electrolysis in a two‐compartment cell proved to be effective for the direct electroactivation of C H acid‐containing compounds vs. catalytic addition processes. Michael adducts (including quaternary carbon centres) and 2‐nitroalkanols were obtained in very good yields and selectivity on application of a catalytic amount of electricity under galvanostatic conditions.     

Synthesis of β‐Lactams by 4‐exo‐tet Cyclization Process Induced by Electrogenerated Cyanomethyl Anion,Part 2:[1] Stereochemical Implications

An efficient electrochemically induced synthesis of chiral cis β‐lactams has been described, via deprotonation of chiral amides containing an acidic methylene group and a bromine atom as leaving group and bearing a chiral auxiliary or amine function. The electrogenerated base – cyanomethyl anion – is easily obtained by galvanostatic reduction of acetonitrile‐tetraethylammonium hexafluorophosphate solutions under very mild conditions. The yields are high and the cis‐diastereoselection complete. The use of starting chiral amides has allowed in many cases the preparation of the most abundant isomer in a pure form.     

Electrochemically generated base-promoted synthesis and biological activities of 2,4-disubstituted carbonotrithioates

The electrosynthesis of new 2,4-dialkylcarbonotrithioates, in satisfactory yields, starting from arylthiols and carbon disulfide using an electrogenerated base (EGB) that is reported to promote the reaction is reported. The EGB was prepared by pro-base-free electrolysis of acetonitrile under galvanostatic conditions using a sacrificial magnesium anode. The as-prepared compounds were fully characterized by ¹H, ¹³C, ¹⁹F NMR spectroscopy and mass spectrometry. The antimicrobial and cytotoxic activities of some representative compounds were investigated against human pathogenic bacteria, colon and lung cancer cell lines. Promising results were found against gram-positive and gram-negative bacteria and DLD-1 and A-549 cancer cell lines.     

基于半导体量子点的电致化学发光试剂的研究进展

电致化学发光因为不需要激发光源,没有杂散光的干扰,实验设备简单且具有背景信号低、灵敏度高的优点,近年来在环境监测、食品安全分析、生物传感和成像等领域都引起了科学家们广泛的关注.在电致化学发光技术中,发光试剂无疑是最重要的组成部件.随着纳米科学和技术的迅猛发展,半导体量子点由于尺寸调控带隙、表面易于改性和表面态依赖性的电...     

The First Catalytic Mannich‐Type Reaction of N‐Alkoxycarbonylamino Sulfones with Silyl Enolates

Bismuth triflate was found to be an efficient catalyst in the Mannich‐type reaction of silyl enolates with N‐alkoxycarbonylamino sulfones. The reaction proceeded smoothly with a low catalyst loading of bismuth triflate (0.5–1.0 mol %) to afford the corresponding protected β‐aminocarbonyl compound in very good yields (up to 96 %).     

Activation of Elemental Sulfur by Electrogenerated Cyanomethyl Anion: Synthesis of Substituted 2‐Aminothiophenes by the Gewald Reaction

The activation of elemental sulfur (S₈) has been achieved by means of electrogenerated cyanomethyl anion [easily obtained by galvanostatic reduction from acetonitrile/tetraethylammonium hexafluorophosphate (MeCN‐Et₄NPF₆)]. The “activated” sulfur reacted with ylidenemalononitriles to give substituted 2‐aminothiophenes in very high yields. This variation of the Gewald reaction has been carried out using only catalytic amounts of electricity and supporting electrolyte. A proposed mechanism for the interaction between S₈ and cyanomethyl anion is described.