Dioxane Complex Research Articles

Study of the Features of the Reaction of Arylcyclopropanes with Nitrozonium Ethyl Sulfate or Nitrozonium Tetrafluoroborate

The reactions of diaryl-, aryl-, and alkyl–arylcyclopropanes with ethyl nitrite in the presence of sulfur trioxide and sulfur trioxide dioxane complex, as well as the reactions of 1-alkyl-2-arylcyclopropanes with NOBF4 were studied. It was found that the attack of the nitrosonium cation, accompanied by the formation of a benzyl carbocation, leads to the formation of isoxazolines. The introduction of bulky alkyl substituents into the cyclopropane ring changes the regioselectivity of nitrosation, favoring the attack of the electrophilic particle on the benzyl position and leading to the competitive formation of an alkyl carbocation. Depending on the structure of the alkyl substituent, both products of intramolecular heterocyclization accompanied by skeletal rearrangements and products formed with the participation of an external nucleophile are formed.

Isolation and Reactivity of a Chlorogermyliumylidene Featuring Two Ge–Cl Units

Deprotonation of 1‐mesityl‐4,5‐diphenyl‐2‐imidazole 1 with nBuLi, followed by salt metathesis reaction with GeCl2·dioxane complex, led to the formation of the chlorogermyliumylidene 2 bearing two Ge–Cl units, which has been isolated and fully characterized by standard spectroscopic and X‐ray diffraction analysis. Structural and NMR spectroscopic data as well as computational studies revealed that the positive charge mainly resides on the Ge atom between two nitrogen atoms. Reduction of 2 with an excess amount of lithium metal resulted in Ge–Ge bond formation concomitant with elimination of one of the Ge atoms of 2, to give rise to the digermylenedilithium compound 3 involving intramolecular coordination of the imines and the lone pairs to the Li atoms.

Isolation of a Cyclic (Alkyl)(amino)germylene.

A 1,4-addition of a dichlorogermylene dioxane complex with α,β-unsaturated imine 1 gave a dichlorogermane derivative 2 bearing a GeC3N five-membered ring skeleton. By reducing 2 with KC8, cyclic (alkyl)(amino)germylene 3 was synthesized and fully characterized. Germylene 3 readily reacted with TEMPO, N2O and S8, producing the 1:2 adduct 4, the oxo-bridged dimer 5 and the sulfido-bridged dimer 6, respectively.

Synthesis and reactivity of a germylene stabilized by a boraguanidinate ligand

The reactivity of a germylene stabilized by a boraguanidinate ligand with various reagents is reported.

Ring-expanded chiral rhombamine macrocycles for efficient NMR enantiodiscrimination of carboxylic acid derivatives

Novel 46-membered chiral rhombamine macrocycles (R,R,R,R)-8a and 8b were synthesized by [2+2] cyclocondensation reactions of (R,R)-1,2-diaminocyclohexane with the corresponding dialdehydes and subsequent reduction with NaBH4. The X-ray crystal structure of 1:4 dioxane complex with (R,R,R,R)-8a indicated a rhombus conformation of the chiral macrocycle. Compounds (R,R,R,R)-8a and 8b were tested as chiral shift reagents for a wide range of α-substituted carboxylic acids and amino acid derivatives. Enantiodiscrimination of 1H NMR signals was observed with ΔΔδ values of up to 0.214ppm.

Crystal Structure of Aura Virus Capsid Protease and Its Complex with Dioxane: New Insights into Capsid-Glycoprotein Molecular Contacts

The nucleocapsid core interaction with endodomains of glycoproteins plays a critical role in the alphavirus life cycle that is essential to virus budding. Recent cryo-electron microscopy (cryo-EM) studies provide structural insights into key interactions between capsid protein (CP) and trans-membrane glycoproteins E1 and E2. CP possesses a chymotrypsin-like fold with a hydrophobic pocket at the surface responsible for interaction with glycoproteins. In the present study, crystal structures of the protease domain of CP from Aura virus and its complex with dioxane were determined at 1.81 and 1.98 Å resolution respectively. Due to the absence of crystal structures, homology models of E1 and E2 from Aura virus were generated. The crystal structure of CP and structural models of E1 and E2 were fitted into the cryo-EM density map of Venezuelan equine encephalitis virus (VEEV) for detailed analysis of CP-glycoprotein interactions. Structural analysis revealed that the E2 endodomain consists of a helix-loop-helix motif where the loop region fits into the hydrophobic pocket of CP. Our studies suggest that Cys397, Cys418 and Tyr401 residues of E2 are involved in stabilizing the structure of E2 endodomain. Density map fitting analysis revealed that Pro405, a conserved E2 residue is present in the loop region of the E2 endodomain helix-loop-helix structure and makes intermolecular hydrophobic contacts with the capsid. In the Aura virus capsid protease (AVCP)-dioxane complex structure, dioxane occupies the hydrophobic pocket on CP and structurally mimics the hydrophobic pyrollidine ring of Pro405 in the loop region of E2.

New Approach to the Synthesis of 3-Alkyl-1,2-dicarba-closo-dodecaboranes: Reaction of Alkyldichloroboranes with Thallium Dicarbollide

A number of 3-alkyl-substituted 1,2-dicarba-closo-dodecaboranes were prepared in good yields via the reaction of alkyldichloroboranes, which were generated in situ through hydroboration of the corresponding alkenes with a dichloroborane–dioxane complex, with thallium dicarbollides in anhydrous dichloromethane at room temperature. This reaction also affords insertion products with new thallium dicarbollides prepared from 3-iodo- and 9-iodo-1,2-dicarba-closo-dodecaboranes. The synthesized 3-alkyl-1,2-dicarba-closo-dodecaboranes can be selectively deboronated at the B(6) atom to form the anionic 3-alkyl-7,8-dicarba-nido-undecaborates. All compounds were characterized by NMR and MS techniques.

Single crystal x-ray diffraction study of dioxane, pyrazine, and pyridine complexes of 3-(1-amino-2,2,2-trifluoroethylidene)-2-imino-1,1,4,5,6,7-hexafluoroindan

Single crystals of complexes of 3-(1-amino-2,2,2-trifluoroethylidene)-2-imino-1,1,4,5,6,7-hexafluoroindan (1) with 1,4-dioxane, pyrazine, and pyridine have been synthesized. Their structure was investigated by X-ray analysis. In crystals of the dioxane complex, compound 1 is present together with its tautomer — 2-amino-3-(1-imino-2,2,2-trifluoroethyl)-1,1,4,5,6,7-hexafluoroindene (1a), and these compounds are in an equilibrium ratio of ∼60:40. Gas-phase quantum chemical calculations have been performed to examine the possibility of a tautomeric equilibrium of enaminoimine 1 in the corresponding complexes.

Facile Hydroboration of (Z)‐1‐Trimethylsilyl‐1‐alkenes with Dichloroborane—Dioxane Complex: An Easy Access to gem‐Dimetalloalkanes Containing Boron and Silicon.

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Facile hydroboration of ( Z)-1-trimethylsilyl-1-alkenes with dichloroborane–dioxane complex: An easy access to gem-dimetalloalkanes containing boron and silicon

( Z)-1-trimethylsilyl-1-alkenes easily prepared by the hydroboration of the corresponding 1-trimethylsilyl-1-alkynes followed by protonolysis with acetic acid, readily react with dichloroborane–dioxane complex in dichloromethane for 6 h. The resulting solution is then treated with 1,3-propane diol in dichloromethane at 0 °C for half an hour to provide the corresponding gem-dimetalloalkanes containing boron and silicon. These α-trimethylsilylalkylboronate esters are purified by vacuum distillation in high yields (72–84%) and the structures of these novel intermediates are further confirmed by selective oxidation with alkaline hydrogen peroxide to provide the corresponding alcohols containing α-trimethylsilyl group in 78–88% isolated yields.

A simple synthesis of B-2-(1-trimethylgermyl-1-alkyl)-1,3,2-dioxaborinanes. Isolation and selective oxidation to 1-trimethylgermyl-1-alkanols

( Z)-1-Trimethylgermyl-1-alkenes easily prepared by the hydroboration of the corresponding 1-trimethylgermyl-1-alkynes followed by protonolysis with acetic acid, readily react with dichloroborane–dioxane complex in dichloromethane for 6 h. The resulting solution is then treated with 1,3-propane diol in dichloromethane at 0 °C for half an hour to provide the corresponding gem-dimetalloalkanes containing boron and germanium. These α-trimethylgermylalkylboronate esters are purified by vacuum distillation in high yields (72–82%) and the structures of these novel intermediates are further confirmed by selective oxidation with alkaline hydrogen peroxide to provide the corresponding alcohols containing α-trimethylgermyl group in very good yields (74–84%).

Effect of Solvent, Hydrogen Bonding, and thickness of Azopolymer Films on Surface Relief Grating

ABSTRACTEpoxy-based copolymers were synthesized with N,N-diglycidyl aniline (DGA) and aniline (An), called poly(DGA-co-An), where azo coupling reactions were performed using amino benzonitrile (ABN) and nitro aniline (NA). Two azopolymers were dissolved with both tetrahydrofuran (THF)/dioxane complex solvent and THF to compare the diffraction efficiencies according to solvent. The thin films spin-cast with THF/dioxane showed the better diffractive efficiency than with THF due to the high boil point of the residual dioxane. The azopolymers of two azo bonds were spin-coated at 800 and 1300 rpm where the thicker film showed the better diffractive efficiency. The epoxy-based copolymers synthesized with diglycidyl ether of bisphenol A (DGEBA) and aniline (An) or 3-hydroxyl aniline (HAn) were coupled with hydroxyl nitro amino benzene (HNAB). Hydroxyl groups in chromophores helped to form hydrogen bonding with the nitrogen atoms in the azo bonds and prevented photoisomerization, showing no surface relief gratings under a normal laser intensity of 100 mW/cm2. Polyurethane-based azopolymers were synthesized with disperse orange 17 (DO17) and toluene-2,4-diisocyanate (TDI), which were no hydroxide groups in the main chains, and showed the better diffractive efficiency than the epoxy-based azopolymers with nitro substituents.

A missing allene of heavy Group 14 elements: 2-germadisilaallene

The first stable 2-germadisilaallene was synthesized by the reduction of a 2 ratio 1 mixture of a stable dialkylsilylene and dichlorogermylene-dioxane complex with KC8; the 2-germadisilaallene showed dynamic disorder similar to the corresponding trisilaallene in the solid state.

3Δ‐1,2,3,4‐Disilagermastannetene: The First Cyclic Germastannene

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3Δ-1,2,3,4-Disilagermastannetene: the first cyclic germastannene

3Δ-1,2,3,4-Disilagermastannetene, the first cyclic germastannene, was quantitatively synthesized by the reaction of 1- and 2-disilagermirenes with the dichlorostannylene--dioxane complex in THF. The title germastannene is quite stable in the solution, which was explained by the appreciable π(Ge=Sn)-σ*(Si--Cl) orbitals mixing.

Isolable silyl and germyl radicals lacking conjugation with pi-bonds: synthesis, characterization, and reactivity.

The one-electron oxidation reaction of tris[di-tert-butyl(methyl)silyl]silyl and -germyl anions with dichlorogermylene-dioxane complex results in the formation of stable tris[di-tert-butyl(methyl)silyl]silyl and -germyl radicals 1 and 2, representing the first isolable radical species of heavier Group 14 elements lacking stabilization by conjugation with pi-bonds. The crystal structures of both silyl and germyl radicals 1 and 2 showed a completely planar geometry around the radical centers. The ESR spectra of 1 and 2 showed strong signals with characteristic satellites due to the coupling with the 29Si and 73Ge nuclei. The small values of the hyperfine coupling constants a(29Si) and a(73Ge) clearly indicate the pi-character of both radicals, corresponding to a planar geometry and sp2 hybridization of the radical centers. Both 1 and 2 easily undergo halogenation reactions with carbon tetrachloride, 1,2-dibromoethane, and benzyl bromide to form the corresponding halosilanes and halogermanes.

Reaction of the Dioxane Complex of Dichlorogermylene with Siloxanes

The major organogermanium compounds formed by reactions of the dioxane complex of dichlorogermylene with hexamethyldisiloxane, octamethyltrisiloxane, and hexamethyltricyclotrisiloxane are bis(trimethylsiloxy)dichlorogermane, 3,3-dichloro-1,1,1,5,5,7,7,7-octamethyl-3-germa-2,4,6-trioxa-1,5,7-trisilaheptane, and a cyclic germatetrasiloxane.

Reaction of a Dioxane Dichlorogermylene Complex with Compounds Containing C-H Bonds

The dioxane complex C4H8O2·GeCl2 reacts with compounds containing C-H bonds (C6H14, Me3SiSiMe3, C4H8O2) with preferential formation of their trichlorogermyl derivatives.

DRIFTS and NIR Raman investigations on unsupported and supported allyl–lanthanoid complexes — catalysts for the polymerization of butadiene

Unsupported and supported Nd(C 3H 5) 3·dioxane and La(C 3H 5) 3·1.5 dioxane complexes were investigated by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), Raman spectroscopy and temperature-programmed reaction spectroscopy (TPRS). The obtained results allow conclusions concerning the structure and thermal stability of metal complexes, as well as their bonding properties. A structural model was developed for such allyl compounds based mainly on the vibrational spectroscopy data. This model was used to interpret the structural changes of these allyl–lanthanide complexes after being supported on methylaluminoxan (MAO)-modified silica (WITCO).

Intramolecular effect of the copper(II) ion on the fluorine NMR chemical shifts of the dioxane complexes of copper polyfluorocarboxylates

Intramolecular effect of the copper(II) ion on the fluorine NMR chemical shifts of the dioxane complexes of copper polyfluorocarboxylates