trans-Ethyl­enedi-p-phenyl­ene diacetate

The centrosymmetric title compound, C18H26O4, was prepared in high yield from 4-acetoxy­styrene via Ru-catalysed homo-olefin metathesis. Exclusive formation of the E-configurated isomer was observed. In the crystal, a strong C—H⋯π inter­molecular inter­action links the mol­ecules together

trans-1,2-Bis(3,5-dimethoxy­phen­yl)ethene

The title compound, C18H20O4, was prepared in high yield from 3,5-dimethoxy­styrene via a Ru-catalysed homo-olefin metathesis. Exclusive formation of the E-configurated isomer was observed. Inter­estingly, one symmetric unit contains two mol­ecules adopting an s-syn-anti and and an all-s-anti conformation

Synthesis, characterization and antifungal assessment of optically active bis-organotin compounds derived from (S)-BINOL diesters

Background: Organotin(IV) derivatives have appeared recently as potential biologically active metallopharmaceuticals exhibiting a variety of therapeutic activities. Hence, it is important to study the synthesis of new organotin compounds with low toxicity that may be of pharmacological interest.Objectives:This study focuses on the synthesis of new bis-stannylated derivatives with C2 symmetry that could be tested as antifungal agents against two clinical important fungal species, Cryptococcus neoformans and Candida albicans.Methods:The radical addition of triorganotin hydrides (R3SnH) and diorganotin chlorohydrides (R2ClSnH) to bis-α,β-unsaturated diesters derived from (S)-BINOL led to the corresponding new bis-stannylated derivatives with C2 symmetry. Nine pure organotin compounds were synthesized with defined stereochemistry. Four of them were enantiomerically pure and four were diastereoisomeric mixtures.Results:All new organotin compounds were fully characterized, those with phenyl ligands bonded to tin were the most active compounds against both the strains (Cryptococcus neoformans and Candida albicans), with activity parameters of IC50 close to those of the reference drug (amphotericin B).Conclusion:Nine pure organotin compounds with C2 symmetry were synthesized with defined stereochemistry and their antifungal properties were tested against two clinical important fungi with IC values close to those of the reference drug. The structure-containing preferably two or three phenyl groups joined to the tin atom were highly active against both the strains compared with those possessing tri-n-butyl groups.Fil: Costantino, Andrea Rosana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Neudörfl, Jörg M.. Universitat zu Köln; Alemania. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; ArgentinaFil: Ocampo, Romina Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Svetaz, Laura Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas; ArgentinaFil: Zacchino, Susana Alicia Stella. Universitat zu Köln; AlemaniaFil: Koll, Liliana Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Química del Sur. Universidad Nacional del Sur. Departamento de Química. Instituto de Química del Sur; ArgentinaFil: Mandolesi, Sandra Delia. Universidad Nacional del Sur; Argentin

Ammonium Pertechnetate in Mixtures of Trifluoromethanesulfonic Acid and Trifluoromethanesulfonic Anhydride

Ammonium pertechnetate reacts in mixtures of trifluoromethanesulfonic anhydride and trifluoromethanesulfonic acid under final formation of ammonium pentakis(trifluoromethanesulfonato)oxidotechnetate(V), (NH4)2[TcO(OTf)5]. The reaction proceeds only at exact concentrations and under the exclusion of air and moisture via pertechnetyl trifluoromethanesulfonate, [TcO3(OTf)], and intermediate TcVI species. 99Tc nuclear magnetic resonance (NMR) has been used to study the TcVII compound and electron paramagnetic resonance (EPR), 99Tc NMR and X-ray absorption near-edge structure (XANES) experiments indicate the presence of the reduced technetium species. In moist air, (NH4)2[TcO(OTf)5] slowly hydrolyses under formation of the tetrameric oxidotechnetate(V) (NH4)4[{TcO(TcO4)4}4] ⋅10 H2O. Single-crystal X-ray crystallography was used to determine the solid-state structures. Additionally, UV/Vis absorption and IR spectra as well as quantum chemical calculations confirm the identity of the species

(RS)-Tricarbon­yl(η4-1,3-diacet­oxy-5,5-dimethyl­cyclo­hexa-1,3-diene)iron(0)

In the title compound, [Fe(C12H16O4)(CO)3], the diene moiety of the mol­ecule is virtually planar, with a C—C—C—C torsion angle of −1.4 (2)°. The six-membered ring exhibits a boat conformation, with torsion angles of 46.2 (2) and 46.5 (3)° for a double-bond and the two attached Csp 3 atoms. The Fe atom is coordinated to all four of the diene C atoms, with bond lengths between 2.041 (2) and 2.117 (2) Å. The Fe(CO)3 tripod adopts a conformation with one CO ligand eclipsing the Csp 3—Csp 3 single bond

Potassium (1-methoxy­carbonyl-2-methyl­prop-2-en-2-yl­idene)azinate

In the title compound, K+·C6H8NO4 −, the K+ cations have a coordination number of seven and are surrounded by four bidentate azinate anions. The methyl­ene groups of the anions are always directed towards the coordinated potassium cations. The N—C—C—C torsion angle is 101.2 (2)°. The orthogonal non-conjugated nature of the salt confirms the supposed geometry and reactivity of this compound

Synthetic α-Helical Peptides as Potential Inhibitors of the ACE2 SARS-CoV-2 Interaction

During viral cell entry, the spike protein of SARS-CoV-2 binds to the α1-helix motif of human angiotensin-converting enzyme 2 (ACE2). Thus, alpha-helical peptides mimicking this motif may serve as inhibitors of viral cell entry. For this purpose, we employed the rigidified diproline-derived module ProM-5 to induce α-helicity in short peptide sequences inspired by the ACE2 α1-helix. Starting with Ac-QAKTFLDKFNHEAEDLFYQ-NH2 as a relevant section of α1, a series of peptides, N-capped with either Ac-βHAsp-[ProM-5] or Ac-βHAsp-PP, were prepared and their α-helicities were investigated. While ProM-5 clearly showed a pronounced effect, an even increased degree of helicity (up to 63 %) was observed in sequences in which non-binding amino acids were replaced by alanine. The binding affinities of the peptides towards the spike protein, as determined by means of microscale thermophoresis (MST), revealed only a subtle influence of the α-helical content and, noteworthy, led to the identification of an Ac-βHAsp-PP-capped peptide displaying a very strong binding affinity (KD=62 nM)

Ammonium Pertechnetate in Mixtures of Trifluoromethanesulfonic Acid and Trifluoromethanesulfonic Anhydride

Ammonium pertechnetate reacts in mixtures of trifluoromethanesulfonic anhydride and trifluoromethanesulfonic acid under final formation of ammonium pentakis(trifluoromethanesulfonato)oxidotechnetate(V), (NH$_{4}$)$_{2}$ [TcO(OTf) $_{5}$]. The reaction proceeds only at exact concentrations and under the exclusion of air and moisture via pertechnetyl trifluoromethanesulfonate, [TcO$_{3}$(OTf)], and intermediate Tc$^{VI}$ species. $^{99}$Tc nuclear magnetic resonance (NMR) has been used to study the Tc$^{VII}$ compound and electron paramagnetic resonance (EPR), $^{99}$Tc NMR and X-ray absorption near-edge structure (XANES) experiments indicate the presence of the reduced technetium species. In moist air, (NH$_{4}$)2[TcO(OTf)5] slowly hydrolyses under formation of the tetrameric oxidotechnetate(V) (NH$_{4}$)$_{4}$ [{TcO(TcO$_{4}$)$_{4}$}$_{4}$] ⋅10 H$_{2}$O. Single-crystal X-ray crystallography was used to determine the solid-state structures. Additionally, UV/Vis absorption and IR spectra as well as quantum chemical calculations confirm the identity of the species

Metal-mediated aminocatalysis provides mild conditions: Enantioselective Michael addition mediated by primary amino catalysts and alkali-metal ions

Four catalysts based on new amides of chiral 1,2-diamines and 2-sulfobenzoic acid have been developed. The alkali-metal salts of these betaine-like amides are able to form imines with enones, which are activated by Lewis acid interaction for nucleophilic attack by 4-hydroxycoumarin. The addition of 4-hydroxycoumarin to enones gives ee’s up to 83% and almost quantitative yields in many cases. This novel type of catalysis provides an effective alternative to conventional primary amino catalysis were strong acid additives are essential components

Lithium phosphonate umpolung catalysts: Do fluoro substituents increase the catalytic activity?

Fluorinated and nonfluorinated phosphonates are employed as precatalysts in lithium phosphonate catalyzed cross benzoin couplings. Surprisingly, a decreased catalytic activity for the fluorinated precatalysts compared to the nonfluorinated systems is observed. Furthermore, the ring size of six, seven and nine membered ring catalysts appears not to be crucial for their catalytic activity