Malonate Group Research Articles

An attempted oxidative coupling approach to the scholarinine A framework

In this manuscript, an oxidative carbon–carbon bond forming reaction to construct the framework of alkaloids such as scholarinine A is explored using a constrained substrate. Instead of the desired carbon–carbon bond formation between an indole C3 position and a malonate group, a competing carbon–nitrogen bond between the malonate and indole C3 position was observed to form. This work adds to the growing body of substrates for oxidative carbon–carbon bond formation and importantly, demonstrates that these reactions are challenging for some conformationally constrained substrates.

Atroposelective Synthesis of 2‐Arylindoles via Chiral Phosphoric Acid‐Catalyzed Direct Amination of Indoles†

Comprehensive SummaryIndole‐based atropisomers are a very important class of axially chiral compounds. However, the atroposelective synthesis of axially chiral 2‐arylindole remains largely unexplored. In this study, we report the successful synthesis of atropisomeric 2‐arylindoles using direct amination of indoles with p‐quinonediimines in the presence of chiral phosphoric acid as a catalyst. Quinonediimine acts as an aminating reagent through formal polarity inversion of imine. The malonate group on the 2‐aryl of 2‐indoles was found to be essential for high enantioselectivity of the products. This could be due to the additional interaction between the ester group and the catalyst, as well as the intramolecular hydrogen bonding. Our findings provide a new strategy for the asymmetric construction of 2‐arylindole atropisomers.

Comparison of Reactive Sites in 2(1H)-Quinolone Derivatives for the Detection of Biologically Important Sulfur Compounds.

Novel fluorescent probes based on 2(1H)-quinolone skeleton containing a malonate group (Q1-Q3) were synthesized and proposed for biothiols detection. Their chemical reactivity toward thiols was compared to the reactivity of derivative having a dicyanovinyl group (Q4) as a reactive site. The detailed photophysical properties of these compounds were assessed through the determination of absorption and fluorescence spectra, fluorescence quantum yield, and fluorescence lifetime. In the presence of biothiols, an increase in the fluorescence intensity of compounds Q1-Q3 and a hypsochromic shift in their emission bands were observed. In contrast, the compound with the dicyanovinyl group (Q4) in the presence of biothiols and cyanide ion showed the quenching of fluorescence, while a fluorescence "turn on" effect was observed toward reactive sulfur species.

Si‐Tethered Bis‐ and Tris‐Malonates for the Regioselective Preparation of Fullerene Multi‐Adducts

AbstractBis‐ and tris‐malonates constructed around a silicon atom have been prepared by reaction of malonate derivatives bearing an alcohol function with di‐tert‐butylsilyl bis(trifluoromethanesulfonate) and tert‐butyl(trichloro)silane, respectively. These compounds have been used for the regioselective bis‐ and tris‐functionalization of C60 under Bingel conditions. By changing the nature of the linker between the central Si atom and the reactive malonate groups, the malonate precursors have been optimized to produce specific bis‐ and tris‐adducts with excellent regioselectivity. A complete understanding of the electronic and stereochemical factors governing the regioselectivity has been obtained by combining computational studies with a complete analysis of the by‐products formed during the reactions of the Si‐tethered tris‐malonates with C60. Finally, desilylation reactions of the resulting fullerene bis‐ and tris‐adducts have been carried out to generate the corresponding acyclic fullerene bis‐ and tris‐adducts bearing alcohol functions.

Chemo- and Regioselective Multiple C(sp2 )-H Insertions of Malonate Metal Carbenes for Late-Stage Functionalizations of Azahelicenes.

Chiral quinacridines react up to four times, step-by-step, with α-diazomalonates under RuII and RhII catalysis. By selecting the catalyst, [CpRu(CH3 CN)3 ][PF6 ] (Cp=cyclopentadienyl) or Rh2 (oct)4 , chemo and regioselective insertions of derived metal carbenes are achieved in favor of mono- or bis-functionalized malonate derivatives, respectively, (r.r.>49 : 1, up to 77 % yield, 12 examples). This multi-introduction of malonate groups is particularly useful to tune optical and chemical properties such as absorption, emission or Brønsted acidity but also cellular bioimaging. Density-functional theory further elucidates the origin of the carbene insertion selectivity and also showcases the importance of conformations in the optical response.

Chemo‐ and Regioselective Multiple C(sp2)−H Insertions of Malonate Metal Carbenes for Late‐Stage Functionalizations of Azahelicenes

AbstractChiral quinacridines react up to four times, step‐by‐step, with α‐diazomalonates under RuII and RhII catalysis. By selecting the catalyst, [CpRu(CH3CN)3][PF6] (Cp=cyclopentadienyl) or Rh2(oct)4, chemo and regioselective insertions of derived metal carbenes are achieved in favor of mono‐ or bis‐functionalized malonate derivatives, respectively, (r.r.>49 : 1, up to 77 % yield, 12 examples). This multi‐introduction of malonate groups is particularly useful to tune optical and chemical properties such as absorption, emission or Brønsted acidity but also cellular bioimaging. Density‐functional theory further elucidates the origin of the carbene insertion selectivity and also showcases the importance of conformations in the optical response.

Probing the Binding Requirements of Modified Nucleosides with the DNA Nuclease SNM1A.

SNM1A is a nuclease that is implicated in DNA interstrand crosslink repair and, as such, its inhibition is of interest for overcoming resistance to chemotherapeutic crosslinking agents. However, the number and identity of the metal ion(s) in the active site of SNM1A are still unconfirmed, and only a limited number of inhibitors have been reported to date. Herein, we report the synthesis and evaluation of a family of malonate-based modified nucleosides to investigate the optimal positioning of metal-binding groups in nucleoside-derived inhibitors for SNM1A. These compounds include ester, carboxylate and hydroxamic acid malonate derivatives which were installed in the 5′-position or 3′-position of thymidine or as a linkage between two nucleosides. Evaluation as inhibitors of recombinant SNM1A showed that nine of the twelve compounds tested had an inhibitory effect at 1 mM concentration. The most potent compound contains a hydroxamic acid malonate group at the 5′-position. Overall, our studies advance the understanding of requirements for nucleoside-derived inhibitors for SNM1A and indicate that groups containing a negatively charged group in close proximity to a metal chelator, such as hydroxamic acid malonates, are promising structures in the design of inhibitors.

Light‐Controlled Regioselective Synthesis of Fullerene Bis‐Adducts

AbstractMulti‐functionalization and isomer‐purity of fullerenes are crucial tasks for the development of their chemistry in various fields. In both current main approaches—tether‐directed covalent functionalization and supramolecular masks—the control of regioselectivity requires multi‐step synthetic procedures to prepare the desired tether or mask. Herein, we describe light‐responsive tethers, containing an azobenzene photoswitch and two malonate groups, in the double cyclopropanation of [60]fullerene. The formation of the bis‐adducts and their spectroscopic and photochemical properties, as well as the effect of azobenzene photoswitching on the regiochemistry of the bis‐addition, have been studied. The behavior of the tethers depends on the geometry of the connection between the photoactive core and the malonate moieties. One tether lead to a strikingly different adduct distribution for the E and Z isomers, indicating that the covalent bis‐functionalization of C60 can be controlled by light.

Light-Controlled Regioselective Synthesis of Fullerene Bis-Adducts.

Multi-functionalization and isomer-purity of fullerenes are crucial tasks for the development of their chemistry in various fields. In both current main approaches-tether-directed covalent functionalization and supramolecular masks-the control of regioselectivity requires multi-step synthetic procedures to prepare the desired tether or mask. Herein, we describe light-responsive tethers, containing an azobenzene photoswitch and two malonate groups, in the double cyclopropanation of [60]fullerene. The formation of the bis-adducts and their spectroscopic and photochemical properties, as well as the effect of azobenzene photoswitching on the regiochemistry of the bis-addition, have been studied. The behavior of the tethers depends on the geometry of the connection between the photoactive core and the malonate moieties. One tether lead to a strikingly different adduct distribution for the E and Z isomers, indicating that the covalent bis-functionalization of C60 can be controlled by light.

Synthesis, Biological Activity and Action Mechanism Study of Novel Chalcone Derivatives Containing Malonate

A series of novel chalcone malonate derivatives were synthesized and their antibacterial and antiviral activities were evaluated. All target compounds were characterized by spectral data. The results of antimicrobial bioassay showed that one compound (diethyl [3-(naphthalen-2-yl)-1-(3-nitrophenyl)-3-oxopropyl]propanedioate) showed excellent antibacterial activity against Xanthomonas oryzae pv. oryzae (Xoo), with an EC50 value of 10.2 μg/mL, which is significantly superior to bismerthiazol (71.7 μg/mL) and thiodiazole copper (97.8 μg/mL). At the same time, the mechanism of two compounds was confirmed by scanning electron microscopy. In addition, another compound (diethyl [3-(naphthalen-2-yl)-1-(4-nitrophenyl)-3-oxopropyl]propanedioate) showed significant curative activity to tobacco mosaic virus, with a value of 74.3 %, which was superior to 53.3 % of ningnanmycin. The results of microscale thermophoresis also showed that the Kd value of the combination of two compounds with the coat protein of tobacco mosaic virus was 0.211 and 0.166 μmol/L, which was better than 0.596 μmol/L of ningnanmycin. At the same time, the molecular docking of two compounds with tobacco mosaic virus-coat protein shows that the compound is well embedded in the pocket between the two subunits of tobacco mosaic virus-coat protein. These results show that chalcone derivatives containing malonate group can be considered as activators in the design of antibacterial and antiviral agents.

Synthesis of new Carnitine Palmitoyltransferase I inhibitors derivatives of C75

Carnitine Palmitoyltransferase (CPT1) is an enzyme that catalyzes the transport of fatty acids from the cytosol into the mitochondria. CPT1 inhibition in the hypothalamus increases fatty acid levels, which produces an increased expression of anorexigenic neuropeptides, a sign of satiety. C75 acts as an antiobesity predrug. In vivo C75, is converted into C75-CoA adduct, which is a potent inhibitor of CPT1 and produces a loss of appetite and body weight. In this work, we present three new derivatives of C75, where the carboxylic group is replaced by a carnitine unit, malonic group, and a hydroxyl group with changes from trans to cis relative stereochemistry. Our results suggest that introducing a bigger group than carboxylic in β position or cis relative configuration of the lactone leads to a decrease of CPT1 inhibitory activity.

A vitamin K-dependent carboxylase orthologue is involved in antibiotic biosynthesis

Vitamin K-dependent carboxylase (VKDC) enzymes modify glutamate residues in mammalian vitamin K-dependent proteins, generating γ-carboxyglutamic acids with malonate moieties that mediate important physiological responses such as blood coagulation. Proteins with sequence similarity to mammalian VKDC are also found in bacteria; however, their function remains unknown. The antibiotic malonomycin from Streptomyces rimosus contains an unusual malonate group, of unknown origin, that is essential for its biological activity. Here, we show that a bacterial VKDC orthologue (MloH) is responsible for the malonic acid moiety in malonomycin. Using CRISPR/Cas9 gene editing, complementation and mutagenesis experiments, this VKDC-like enzyme was shown to α-carboxylate an aspartyl residue within a hybrid polyketide–nonribosomal peptide intermediate during malonomycin biosynthesis. This study reveals a highly unusual biosynthetic pathway to malonic acid-containing metabolites, providing a functional role for VKDC-like proteins in prokaryotes and a vitamin K-dependent carboxylation reaction with a non-proteinogenic substrate. The function of putative bacterial vitamin K-dependent carboxylases (VKDCs) has so far been uncertain. Now, Micklefield and co-workers show that a bacterial VKDC orthologue is involved in the biosynthesis of the antibiotic malonomycin, generating an unusual malonic acid moiety that is essential for its biological activity.

Iron-Strapped Porphyrins with Carboxylic Acid Groups Hanging over the Coordination Site: Synthesis, X-ray Characterization, and Dioxygen Binding.

A series of myoglobin active site analogues were synthesized and characterized to investigate the dioxygen binding effects of a flexible distal strap over the coordination site. These four synthetic models differ mostly by the shape and polarity of their cavities and also possibly by motion of the distal strap attached to two of the meso carbon atoms. Each of the four models has an intramolecular nitrogen base that axially binds the iron(II) cation inside the porphyrin, but they differ either by the nature of the distal strap or by its mobility. The overhanging distal group is either a generally apolar ethyl malonate group or a polar malonic acid group which is also a strong H-bond donor. It is shown that, in the ferrous complex 2b bearing such an overhung malonic acid group in close proximity to the iron atom, the equilibrium rate for dioxygen binding is significantly enhanced in comparison to that of its ester precursor. In the case of the analogous complex 1b bearing a more mobile distal strap, one of the carboxylic acid groups binds the iron(II) cation, leading to a six-coordinate ferrous complex. Unexpectedly, this complex proved to be high-spin (S = 2) as shown by solid-state magnetic measurements. Whereas this unprecedented complex still binds dioxygen, the formation of the intramolecular six-coordinate complex precluded the measurement of its dioxygen affinity through direct quantitative gas titration monitored by UV-vis spectroscopy. However, in this case, the determination of the kinetic rate constants for dioxygen binding and dissociation by laser flash photolysis allowed the evaluation of the equilibrium rate. Together with three previous X-ray structures of iron complexes in the ααββ conformation, the structure of the cavity and the shape of the relaxed distal strap are also discussed with the consideration of the resolution of X-ray structures of two different free-base ligands in the ααββ conformation, with one bearing the ethyl malonate group and the second one bearing the malonic acid group. A third X-ray structure of the analogous ligand with the overhanging ethyl malonate group in the αβαβ series allows a direct comparison of the distal strap in both geometries. This work reveals that the compound with the overhanging carboxylic acid group which cannot directly interact with the ferrous heme exhibits an increased dioxygen affinity by 2 orders of magnitude versus its ester precursor.

A Novel Strategy for Synthesis of Polystyrene/Fe3O4 Nanocomposite: RAFT Polymerization, Functionalization, and Coordination Techniques

ABSTRACTA facile strategy for the synthesis of polystyrene/Fe3O4 nanocomposite is suggested. For this purpose, styrene and 4-chloromethyl styrene monomers was copolymerized through reversible addition of fragmentation chain transfer technique [P(St-co-CMSt)] and then the chlorine groups of CMSt units were converted to diethyl malonate groups through a nucleophilic substitution reaction. Afterward, esteric groups of diethyl malonate were hydrolyzed to afford carboxylic acid-functionalized polystyrene. This polymer with carboxylic acid groups can adsorbed onto the surface of Fe3O4 nanoparticles through the interaction with hydroxyl groups onto the surface of the nanoparticles. We envision that the synthesized PSt/Fe3O4 nanocomposite may be find applications in electromagnetic interference shielding and environment sciences.

Performance of a high resolution chemically amplified electron beam resist at various beam energies

A novel negative tone molecular resist molecule featuring a tert-butyloxycarbonyl protected phenol malonate group bonded to a 1,8-Diazabicycloundece-7-ene is presented. The resist shows high-resolution capability in electron beam lithography at a range of beam energies. The resist demonstrated a sensitivity of 18.7μC/cm2 at 20kV. Dense features with a line width of 15nm have been demonstrated at 30kV, whilst a feature size of 12.5nm was achieved for dense lines at 100kV.

Long-range antiferromagnetic order in malonate-based compounds Na2M(H2C3O4)2·2H2O (M = Mn, Fe, Co, Ni).

The recently discovered metal-malonate compounds of formulae Na2M(H2C3O4)2·2H2O with M = Mn, Fe, Co, Ni are investigated for their magnetic properties. While the Cu-based material is a weak ferromagnet, all other members present antiferromagnetic interactions. Neutron powder diffraction experiments reveal the establishment of a long range magnetic order at low temperature in the Pbca Shubnikov magnetic group. The magnetic structures are characterized by antiferromagnetic layers perpendicular to [001]. These layers are stacked antiparallel (M = Fe) or parallel (M = Mn, Ni) in the (a, c) plane. Magnetic moments are collinear to b for the former and to c for the latter. The M = Co malonate exhibits a non-collinear magnetic structure intermediate between the two latter, with components along b and c. Density functional theory calculations indicate that the dominant magnetic interaction, J1, occurs along a malonate group via a carboxylate and links two transition metals within the same layer, while other interactions (inter- or intra-layer) are much weaker, so that these compounds present the dominant characteristics of 2D-antiferromagnets.

Synthesis, structure and electrochemical properties of metal malonate Na2M(H2C3O4)2·nH2O (n = 0, 2) compounds and comparison with oxalate Na2M2(C2O4)3·2H2O compounds

Oxalate and malonate based compounds were prepared by hydrothermal method. The crystal structure of oxalate compounds of formulae Na2M2(C2O4)3·2H2O (with M = Mn, Fe, Co, Ni and Mg) was confirmed from single crystal diffraction. We report here a series of new malonate compounds Na2M(H2C3O4)2·2H2O with M = Mn, Fe, Co, Ni, Zn and Mg, whose structure, thermal and electrochemical performances are presented. Metal malonate compounds crystallize in an orthorhombic structure built upon MO6 octahedra connected with malonate groups to form a layered structure. The removal/uptake of water from the malonate members was found to be reversible and the crystal structure of the anhydrous Na2Mn(H2C3O4)2 is solved from powder diffraction and presents similarities with the hydrated phase. However, sodium 3d-metal oxalates/malonates compounds show poor electrochemical activity.

Customized Buchwald‐Type Phosphines Bearing an “Inverted” Pyrimidinium Betaine as an Aryl Group Surrogate – Synthesis and Coordination Chemistry with Gold(I)

AbstractA new ligand scaffold inspired by Buchwald‐type phosphines is disclosed. Its design consists of the formal replacement of the distal aryl group of the original archetype by a pyrimidinium betaine connected to the o‐phosphinophenyl moiety through the C‐5 position of its malonate subunit. A productive synthetic pathway towards this phosphine is described along with its ability to coordinate to a gold(I) center. A weak bonding interaction between the metal center and the malonate group is observed in the solid state.

Novel Molecular Resist for EUV and Electron Beam Lithography

A novel molecular resist molecule was prepared by incorporation of 1,8-diazabicycloundece-7-ene into a tert-butyloxycarbonyl protected phenol malonate group. The resist shows high-resolution capability in both extreme ultraviolet (EUV) and electron beam lithography.

Synthesis and characterization of a trans-1 hexakis-fullerene linker that forms crystalline polymers with silver salts.

A new flexible hexakis-fullerene adduct with two bis(pyridin-4-ylmethyl)malonate groups located at trans-1 positions was synthesized. Via reaction with Ag(PF6) under two different conditions, two new 1D coordination polymers were obtained; under a nitrogen atmosphere, the silver ions are connected by argentophilic interactions but under an ambient atmosphere, the silver ions exhibit no interaction between them but coordination to the (H2PO4)(-) ions.