Synthesis of narrowly size-distributed metal salt/poly(HEMA) hybrid particles in inverse miniemulsion: versatility and mechanism

Hybrid particles containing different hydrophilic metal salts such as tetrafluoroborates of iron(II), cobalt(II), nickel(II), copper(II), and zinc(II), and nitrates of cobalt(II), nickel(II), copper(II), zinc(II), and iron(III), and cobalt(II) chloride were synthesized via inverse miniemulsion polymerization of 2-hydroxyethyl methacrylate (HEMA). All salts delivered narrowly size-distributed hybrid particles with the exception of iron(III), where only the nitrate salt could be successfully employed. The size and size distribution of the hybrid particles were characterized by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The particle morphology and the distribution of salt in the dried particles were observed by TEM. The influences of the type of metal salts and salt content on the particle size distribution were extensively investigated.     

The Direct Synthesis of Arylxenon Trifluoromethanesulfonates via electrophilic substitution

The reaction of xenonbis(trifluoroacetate) and trifluoromethanesulfonic acid (triflic acid) gave the new, highly reactive unsymmetrical xenon-oxo species CF₃COOXeOSO₂CF₃. Benzene derivates, containing electron withdrawing substituents such as -F, -CF₃, -Cl or -NO₂ were electrophilic attacked by this intermediate to yield arylxenon trifluoromethanesulfonates. Via this one-pot synthesis trifluoromethanesulfonates with the cations [Xe(2,4,6-F₃C₆H₂)]⁺, [Xe(2-F-5-NO₂C₆H₃)]⁺, [Xe(2-F-5-CF₃C₆H₃)]⁺ and [Xe(3,5-(CF₃)₂C₆H₃)]⁺ were prepared. All compounds were characterized by their NMR, mass, and vibrational spectra. Additionally, several new arylxenon trifluoromethanesulfonates were detected by ¹²⁹Xe-NMR spectroscopy as products of the reaction of 1,3-F₂C₆H₄ and further deactivated benzenes with xenontrifluoroacetate trifluoromethane sulfonate. Fluoro substituents in ortho position to xenon significantly increase the thermal stability of the arylxenon trifluoromethanesulfonates obtained. The molecular structure of [Xe(2,6-F₂C₆H₃)][OSO₂CF₃] was determined by single crystal diffraction methods. The arylxenon unit is weakly coordinated by one oxygen atom of the CF₃SO₃ anion. The salt crystallizes in the triclinic space group P1 , a = 880.9(3) pm, b = 1093.9(5) pm, c = 1209.8(5) pm, α = 89.04(4)°, β = 74.23(3)°, γ = 86.03(3)°, Z = 4.     

Reaction of 3-(R-methylidene)-2-ethoxylindolenines with <Emphasis Type="Italic">N,N</Emphasis>'-binucleophiles

Reactions of 3-isopropylidene- and 3-cyclohexylidene-2-ethoxyindolenine tetrafluoroborates with guanidine afford dihydropyrimido[4,5-b]indole derivatives containing a hydroxy group, unlike analogous reactions of 3-arylmethylidene and 3-(dimethylamino)methylidene tetrafluoroborates.     

Reactivity studies of S-methylthiophenium tetrafluoroborates

The polarographic behavior of four S-methylthiophenium tetrafluoroborates, I-IV, has been investigated in Britton-Robinson aqueous buffers. The compounds under study were the S-methylbenzo[b]thiophenium (I), S-methylnaphtho[2,3-b]thiophenium (II), S-methyldibenzothiophenium (III), and S-methylnaphtho[2,1-b]thiophenium (IV) tetrafluoroborates which were obtained from the parent sulfur heterocycles by their reaction with methyl iodide and silver tetrafluoroborate in 1,2-dichloroethane, II and IV being new compounds. Compounds I-IV give two one-electron reduction waves and the more positive wave appears to be associated with an electron transfer from the electrode to the LUMO of the substrate as indicated by the experimental E_1/2 vs calculated LUMO values plot (Figure 2). The rates of demethylation of the ions I-IV with the iodide ion acting as the nucleophile have been determined in the Britton-Robinson buffer (pH 6)-acetonitrile solution at 24°. The results of the polarographic study and of the kinetic studies with the iodide ion confirm the high reactivity of S-methylthiophenium ions which originates in the antiaromatic destabilization of these structures.     

Palladium-catalyzed direct arylation of pyridine N-oxide with 2-bromoacetanilides. Synthesis of benzisoxazolo[2,3-a]pyridinium tetrafluoroborates

The synthesis of a variety of novel benzisoxazolo[2,3-a]pyridinium tetrafluoroborates is described. These compounds are conveniently prepared from pyridine N-oxide via a microwave-promoted palladium-catalyzed direct arylation of pyridine N-oxide with 2-bromoacetanilides to give 2-(2-acetamidoaryl)pyridine N-oxides, followed by hydrolysis, diazotization and intramolecular displacement of nitrogen which affords the target benzisoxazolo[2,3-a]pyridinium tetrafluoroborates.     

Heck reaction of arenediazonium salts with N,N-diprotected allylamines. Synthesis of cinnamylamines and indoles

Novel palladium-catalyzed reactions of arenediazonium tetrafluoroborates with N,N-diprotected allylamines are presented. The reaction of arenediazonium tetrafluoroborates with N,N-(Boc)(2) allylamine allows for an easy approach to cinnamylamines whereas using 2-alkynyl-N-(allyl)trifluoroacetanilides and 2-iodo-N-(allyl)trifluoroacetanilide the reaction provides a useful tool for appending indole rings to aniline fragments.     

Adducts of thianthrene- and phenoxathiin cation radical tetrafluoroborates to 1-alkynes. Structures and formation of 1-(5-thianthreniumyl)- and 1-(10-phenoxathiiniumyl)alkynes on alumina leading to alpha-ketoylides and alpha-ketols

[structure: see text] Thianthrene cation radical tetrafluoroborate (Th*+ BF4(-)) added to the terminal alkynes 1-pentyne, 1-hexyne, 1-heptyne, 1-octyne, 1-nonyne, and 1-decyne to form trans-1,2-bis(5-thianthreniumyl)alkene tetrafluoroborates (1-6). Similarly, addition of phenoxathiin cation radical tetrafluoroborate (PO*+ BF4(-)) to the same alkynes gave 1,2-bis(10-phenoxathiiniumyl)alkene tetrafluoroborates (7-12). The trans configuration of two of the adducts (1 and 4) was shown with X-ray crystallography. When solutions of 1-6 in chloroform were stirred with activated alumina, cis elimination of a proton and thianthrene (Th) occurred with the formation of 1-(5-thianthreniumyl)alkyne tetrafluoroborates (1a-6a). Similar treatment of 8-12 caused elimination of a proton and phenoxathiin (PO) with formation of 1-(10-phenoxathiiniumyl)alkene tetrafluoroborates (8a-12a). Stirring of 1a-6a with alumina for short periods of time caused their conversion into 5-[(alpha-keto)alkyl]thianthrenium ylides (1b-6b) and alpha-ketols, RC(O)CH2OH (1c-6c).     

A Heck–Matsuda Process for the Synthesis of β‐Arylethenesulfonyl Fluorides: Selectively Addressable Bis‐electrophiles for SuFEx Click Chemistry

A Heck–Matsuda process for the synthesis of the otherwise difficult to access compounds, β‐arylethenesulfonyl fluorides, is described. Ethenesulfonyl fluoride (i.e., vinylsulfonyl fluoride, or ESF) undergoes β‐arylation with stable and readily prepared arenediazonium tetrafluoroborates in the presence of the catalyst palladium(II) acetate to afford the E‐isomer sulfonyl analogues of cinnamoyl fluoride in 43–97 % yield. The β‐arylethenesulfonyl fluorides are found to be selectively addressable bis‐electrophiles for sulfur(VI) fluoride exchange (SuFEx) click chemistry, in which either the alkenyl moiety or the sulfonyl fluoride group can be the exclusive site of nucleophilic attack under defined conditions, making these rather simple cores attractive for covalent drug discovery.     

Diferrocenylcyclopropenyl cations. Synthesis, structures, and some chemical properties

Synthesis of diferrocenylcyclopropenyl tetrafluoroborates with hetero-substituents in the three-membered ring, viz., ethoxy, trityloxy, ferrocenyl(phenyl)methoxy, N,N-diethylamino, piperidino, and morpholino, is described. The spatial structure of diferrocenyl(morpholino)cyclopropenyl tetrafluoroborate was established based on the data from X-ray diffraction analysis. Under the action of potassium tert-butoxide, all the diferrocenylcyclopropenyl tetrafluoroborates undergo three-membered ring-opening with formation of the corresponding 2,3-diferrocenylacrylic acid derivatives. A mechanism of the ring-opening is suggested.     

Thiocyanatoarylation of Diethylene Glycol Diacrylate

The example of diethylene glycol diacrylate was used to demonstrate the possibility of thiocyanatoarylation both by one and by two multiple bonds of compounds with two isolated multiple bonds. The reactions of arenediazonium tetrafluoroborates with diethylene glycol diacrylate in aqueous acetone (1:2) in the presence of catalytic amounts of copper gave 1-acryloyloxy-2-[2-(2-thiocyanato-3-arylpropionyloxy)ethoxy]ethanes. The latter were reacted with arenediazonium tetrafluoroborates in aqueous acetone (1:3) to obtain 1-[2-(2-thiocyanato-3-arylpropionyloxy)ethoxy]-2-(2-thiocyanato-3-arylpropionyloxy)ethanes via thiocyanatoarylation by two multiple bonds.     

Formation of new alkynyl(phenyl)iodonium salts and their use in the synthesis of phenylsulfonyl indenes and acetylenes

The preparation of phenylsulfonyl indene derivatives and phenylsulfonyl- acetylenes from readily available alkynyl(phenyl)iodonium tetrafluoroborates and triflates was investigated using phenylsulfinate as nucleophile.     

Hypervalent Iodine in Synthesis 41: A Novel Stereoselective Synthetic Approach to Vinyl Carbonotrithioates

Vinyl esters of carbonotrithioic acids have been stereoselectively prepared by the reaction of potassium carbonotrithioates with vinyl(phenyl)-iodonium tetrafluoroborates with retention or inversion of the configurations.     

Synthesis and studies of chemical properties of arylthallium(III)bis(tetrafluoroborates)

Synthesis of arylthallium(III)bis(tetrafluoroborates) was carried out and their pyrolysis was studied. Synthetic procedure for preparation of fluoroaromatic compounds is developed.     

Assembly of 3-sulfonated 2H-pyrrol-2-ones through the insertion of sulfur dioxide with allenoic amides

Generation of 3-sulfonated 2H-pyrrol-2-ones through a three-component reaction of allenoic amides, sulfur dioxide, and aryldiazonium tetrafluoroborates under metal-free conditions is achieved. This transformation proceeds under mild conditions without the addition of catalysts or additives, giving rise to 3-sulfonated 2H-pyrrol-2-ones in moderate to good yields. Good functional group compatibility is observed. A plausible mechanism is proposed, which is initiated by aryl radicals formed in situ from aryldiazonium tetrafluoroborates and DABCO·(SO₂)₂. Additionally, excellent chemoselectivity and regioselectivity are presented in this transformation.     

Micellar nanocontainers based on sterically hindered cationic phosphonium amphiphiles

Russian Chemical Bulletin - Self-aggregation processes in an H2O—DMF (10%) medium were studied for a homologous series of tri-tert-butyl(n-alkyl)phosphonium tetrafluoroborates (PIL-n, where n...     

Thallium(III) oxide as an oxidative reagent in organic chemistry

Synthesis of arylthallium(III)bis(tetrafluoroborates) was carried out and their pyrolysis was studied. Synthetic procedure for preparation of fluoroaromatic compounds is developed.     

Synthetic studies on a series of functionalized pyrylium salts, 4-chloro- and 4-bromophosphinines

A series of new pyrylium salts that bear sulfonate and phosphonate groups were obtained from the reactions between 2,6-diphenyl-4H-pyran-4-one, sulfonic anhydride, and chlorophosphates, and analyzed spectroscopically. Furthermore, treatment of 2,6-diphenyl-4H-pyran-4-one with phosphoryl chloride or bromide afforded the corresponding 4-chloro- and 4-bromopyrylium tetrafluoroborates in good yield. Subsequently, the synthesis of the corresponding 4-chloro- and 4-bromophosphinines was accomplished by treating the respective chloro- and bromopyrylium tetrafluoroborates with tris(trimethylsilyl)phosphine.     

Catalyst-free Mannich-type reaction of 1-(N-acylamino)alkyltriphenylphosphonium salts with silyl enolates

A catalyst-free reaction of 1-(N-acylamino)alkyltriphenylphosphonium tetrafluoroborates with silyl enolates was developed to prepare β-amino carbonyl compounds. The reported method is a useful approach for the preparation of N-protected β-amino esters as well as N-protected β-amino ketones. The starting 1-(N-acylamino)alkyltriphenylphosphonium tetrafluoroborates are readily available from N-protected α-amino acids. Therefore, the presented approach can be considered a new method for the α-homologation of N-protected α-amino acids to prepare β-amino acid derivatives.     

Saturated Nitrogen-containing Heterocycles. 20. Catalytic Reduction of N-Hydroxyethylpyridinium and Quinolinium Salts

Previously unknown N-(2-hydroxyethyl)perhydroquinolines and N-(2-hydroxyethyl)piperidines were synthesized by catalytic reduction of N-(2-hydroxyethyl)tetrahydroquinolinium and N-(2-hydroxyethyl)tetrahydropyridinium tetrafluoroborates. A scheme for the formation of the hydrogenation products is presented.     

Hypervalent Iodine in Synthesis XXXV: A Simple and Convenient Stereospecific Synthesis of Vinyl Esters of Dithiocarbamic Acids

Vinyl esters of dithiocarbamic acids have been stereospecifically prepared by the reaction of sodium dithiocarbamates with vinyi(phenyi)iodonium tetrafluoroborates with retention or inversion of the configurations.