Sodium Amide Research Articles

Cycloadducts of Furan with Arynes Generated from 2‐Bromo‐1,4,5,8‐tetramethoxynaphthalene and 2,6‐Dibromo‐1,4,5,8‐tetramethoxynaphthalene

The reaction of 2‐bromo‐1,4,5,8‐tetramethoxynaphthalene (7) with sodium amide (or LDA) in the presence of a large excess of furan gave the epoxy compound 9. The similar reaction of 2,6‐dibromo‐1,4,5,8‐tetramethoxynaphthalene (8) afforded the diepoxy compound 10. The crystal structure of antidiepoxide 10 was determined by an X‐ray crystallography.

Copper-Catalyzed Cyclization of Oxime Acetates with 2-Benzylidenemalononitriles for Synthesis of 2?Aminonicotinonitriles

The 2-aminopyridine is the core structure of many potential drug candidates for the treatment of a variety of dis- orders. It is widely used as building block for the synthesis of series nitrogen-containing heterocycles. However, the traditional synthesis of 2-aminopyridines relies on amination of 2-unsubstituted pyridines with sodium amide which is limited to low yield and narrow scope for the using of strongly basic conditions. Oximes and their derivatives are a class of powerful building blocks in organic synthesis. Recently, a series of reports are focus on copper-catalyzed cyclization of oxime esters, and various methods are developed for the construction of five- or six-membered heterocycles. Based on our sustained efforts to copper-catalyzed cyclization for access to heterocyles, we herein report a novel process of copper-catalyzed cyclization of oxime esters with 2-benzylidenemalononitrile for the construction of 2-aminopyridines. Various 2-aminopyridines were ob- tained in middle to good yields under the optimized reaction conditions. In this case, the N—O bond cleavage would occur for oxime esters reduced by copper(I) catalyst, followed by the formation of nucleophilic copper(II) enamide which serve as a precursor in heterocycle synthesis. A representative procedure for the copper-catalyzed construction of 2-aminopyridines by cyclization of oxime esters with 2-benzylidenemalononitrile is as following: The substrate acetophenone O-acetyl oxime (1a, 0.5 mmol, 0.0885 g), 2-benzylidenemalononitrile (2a, 0.5 mmol, 0.0770 g), CuCl (0.1 mmol, 0.0989 g, 20 mol%), and Na- HSO3 (1.0 mmol, 0.1041 g) were added to a 10 mL Schlenk tube, followed by addition of DMF (dried by calcium hydride and freshly distilled, 3 mL). The mixture was stirred at 60 ℃ as monitored by TLC. The solution was then quenched by H2O and extracted with EtOAc (20 mL×3), the combined organic layers were dried over Na2SO4, filtered, and evaporated under vaccum. The residue was purified by column chromatography on silica gel (eluent: light petroleum ether∶ethyl acetate, V∶ V=5∶1) to afford the desired product 4,6-diphenylpyridin-2-amine 3a. Keywords copper; oxime esters; 2-benzylidenemalononitrile; cyclization; 2-aminopyridine

Amidophosphine–Borane Complexes of Alkali Metals and the Heavier Alkaline-Earth Metals: Syntheses and Structural Studies

The N-benzhydrylamido-1,1-diphenylphosphine–borane ligand [Ph2P(BH3)NH(CHPh2)] (1-H) has been prepared via the reaction of an equimolar ratio of the phosphine amine [Ph2PNH(CHPh2)] and the borane adduct [BH3·SMe2] at an ambient temperature. The reaction of 1-H with ((trimethylsilyl)methyl)lithium (neosilyllithium), [LiCH2SiMe3], afforded a three-membered lithium amidophosphine–borane complex with the composition ([η2-Ph2CHNP(BH3)Ph2)Li(THF)2] (2). Analogous reactions with sodium and potassium bis(trimethylsilyl)amides at ambient temperature yielded the respective alkali-metal amidophosphine–borane complexes [{(Ph2CHNP(BH3)Ph2)Na(THF)2}2] (3) and [{(Ph2CHNP(BH3)Ph2)K(THF)2}2] (4), with the loss of hexamethyldisilazane, [(Me3Si)2NH]. The corresponding heavier alkaline-earth-metal complexes [M(THF)2{Ph2P(BH3)N(CHPh2)}2] (M = Ca (5), Sr (6), Ba (7)) can be obtained via the reaction of [M{N(SiMe3)2}2(THF)n] (M = Ca, Sr, Ba) and 1-H. The metal complexes 5–7 can also be prepared via a salt metathesis route, wher...

Catalyst-free synthesis of sodium amide nanoparticles encapsulated in silica gel

Crystalline sodium amide nanoparticles encapsulated in an amorphous silica framework were formed by ammoniation of a precursor material, silica gel loaded with metallic sodium, under mild conditions and without catalysis. This ammoniation was performed in situ on TOSCA beamline at ISIS, RAL, using anhydrous gaseous ammonia. The resulting material exhibits no pyrophoricity and much reduced air- and moisture-sensitivity compared to the bulk amide. The nanoparticles formed will offer a greatly increased surface area for chemical reactions where amide is currently used as an important ingredient for industrial applications. We anticipate that this method of sodium amide production will have a diversity of applications.

Modifying alkylzinc reactivity with 2,2'-dipyridylamide: activation of tBu-Zn bonds for para-alkylation of benzophenone.

Undercover agent: Masquerading as a simple donor-acceptor complex (1), sodium amide substoichiometrically activates tBuZn for the challenging 1,6-addition of a tert-butyl group to benzophenone. In contrast, the nonactivated tBuZn is ineffectual.

Synthesis, characterization and fluorescence properties of boron difluoride pyridyl-β-diketonate derivatives

Five pyridyl-β-diketones were synthesized by Claisen condensation of ethyl nicotinate with various aryl methyl ketones in benzene in the presence of sodium amide as the base, and then reacted with boron trifluoride diethyl etherate in dichloromethane to afford some new boron difluoride pyridyl-β-diketonate derivatives. The compounds obtained were characterized using FTIR, 1H NMR, elemental analysis and mass spectrometry. Their optical properties were studied in DMF by UV–vis absorption and fluorescence spectroscopy. The results showed that these boron complexes exhibited intense fluorescence in the blue–green region (420–490nm) under UV radiation with a relatively high quantum yield. Especially, compounds 4b and 5b displayed much higher quantum yield as compared to compounds 1b, 2b and 3b.

Synthesis and formation mechanism of cubic boron nitride nanorods in lithium bromide molten salt

Cubic boron nitride nanorods (cBNNRs) were synthesized through a simple reaction between boron tribromide and sodium amide in lithium bromide molten salt medium at 600°C in a sealed autoclave system. The cBNNRs observed by transmission electron microscopy have various diameters ranging from 8 to 25nm with aspect ratios of about 10–20. X-ray diffraction and selected area electron diffraction pattern revealed the cubic phase of cBNNRs with a lattice constant a=3.625Å. The B:N ratio obtained by energy dispersive X-ray spectroscopy was 1:1.12, and Fourier transform infrared spectrum showed a characteristic absorption at 1106cm–1. The possible formation mechanism of cBNNRs in molten salt medium is also discussed.

ChemInform Abstract: Interaction of Quinolines Polyfluorinated on the Benzene Moiety with Sodium and Potassium Amides in Liquid Ammonia.

AbstractQuinolines (I) and (III) react with potassium or sodium amides by adding the NH2‐ ion at the 2‐position of the pyridine fragment to afford the quinolineamines (II) and (IV), resp., upon oxidation of the adducts formed.

Substituted homoallenyl aldehydes and their derivatives. Part 1: Homoallenyl aldehydes and protected hydrazones

AbstractThe paper presents a simple synthesis of substituted propargyl vinyl ethers and their subsequent thermally-initiated Claisen rearrangement leading to various 3-substituted homoallenyl aldehydes. Several methods, including Sonogashira coupling, base-promoted substitution on the triple bond by sodium amide or butyllithium, and the preparation of substituted propargyl alcohols, were used in the initial step. Phosphate-protected homoallenyl aldehyde hydrazone derivatives were synthesised and fully characterised. The stereochemistry of 9-anthracene carbaldehyde hydrazone, which, surprisingly, afforded both cis and trans isomers, was established using X-ray analysis.

Low temperature solid-state synthesis of nanocrystalline gallium nitride

Nanocrystalline gallium nitride was synthesized by a solid-state reaction of metallic magnesium powder, gallium sesquioxide and sodium amide in a stainless steel autoclave at a relatively low temperature (400–550°C). The structures and morphologies of the obtained products were derived from X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). XRD patterns indicated that the products were hexagonal GaN (JCPDS card no. 76-0703). The influence of reaction temperature on size of the products was studied by XRD and TEM. Furthermore, the thermal stability and oxidation resistance of the nanocrystalline GaN were also investigated. It had good thermal stability and oxidation resistance below 800°C in air.

Theoretical Studies of High-Pressure Phases, Electronic Structure, and Vibrational Properties of NaNH2

Thermodynamically stable phases of sodium amide (NaNH2) at pressures up to 20 GPa have been determined using the ab initio evolutionary structure prediction. We find that the ground-state phase α-NaNH2 (orthorhombic, Fddd) first transforms into β-NaNH2 (orthorhombic, P21212) at 2.2 GPa; then, γ-NaNH2 (monoclinic, C2/c) becomes stable at 9.4 GPa. In addition to strong ionic bonding between Na+ and [NH2]− ions and covalent bonding between H and N in NH2 groups, the N–H···N hydrogen bonding between neighboring NH2 groups could not be ignored anymore in the high-pressure β-NaNH2, as suggested by the analysis of charge density distribution and structural and vibrational properties. The covalent N–H bonds in the high-pressure phase of NaNH2 are weakened by additional hydrogen bonding, which could be favorable for the hydrogen desorption.

Interaction of quinolines polyfluorinated on the benzene moiety with sodium and potassium amides in liquid ammonia

The interaction of 5,6,7,8-tetrafluoro- (1) and 5,7,8-trifluoro-6-(trifluoromethyl)quinoline (2) with sodium or potassium amide in liquid ammonia proceeds as a nucleophile (NH2−) addition on the 2-position of the pyridine ring, the respective adducts being oxidized to give the respective quinoline-2-amines. In the case of 1 the amide addition is concurrent with aminodefluorination on the 6- and 7-positions. 5,6,8- (3), 5,7,8-trifluoro- (4) and 5,7-difluoroquinolines (5) with one amide equivalent undergo deprotonation of the CH bond flanked by two ortho-fluorine atoms to produce the respective long-lived quinolinyl anions, which can be used as nucleophilic synthons as exemplified by their methylation to yield respective 6- and 7-methylpolyfluoroquinolines. With an excess of potassium amide the originally generated quinolinyl anions add an amide anion on the 2- or 4-position.

ChemInform Abstract: Low‐Temperature Ammonothermal Synthesis of LaTaON2.

AbstractPhase‐pure powders of the title compound are synthesized from a LaTa precursor alloy in supercritical ammonia using sodium amide as a flux (873 K, 100 MPa NH3, 15—75 h).

Sulfonylurea receptor as a target for molecular imaging of pancreas beta cells with 99mTc-DTPA-glipizide

This study was aimed to assess pancreas beta cell activity using (99m)Tc-diethyleneaminepentaacetic acid-glipizide (DTPA-GLP), a sulfonylurea receptor agent. The effect of DTPA-GLP on the blood glucose level in rats was also evaluated. DTPA dianhydride was conjugated with GLP in the presence of sodium amide, yielding 60%. Biodistribution and planar images were obtained at 30-120min after injection of (99m)Tc-DTPA-GLP (1mg/rat, 0.74 and 11.1MBq per rat, respectively) in normal female Fischer 344 rats. The control group was given (99m)Tc-DTPA. To demonstrate pancreas beta cell uptake of (99m)Tc-DTPA-GLP via a receptor-mediated process, a group of rats was pretreated with streptozotocin (a beta cell toxin, 55mg/kg, i.v.) and the images were acquired at immediately-65min on day 5 post-treatment. The effect on the glucose levels after a single administration (ip) of DTPA-GLP was compared to glipizide (GLP) for up to 6h. The structure of DTPA-GLP was confirmed by NMR, mass spectrometry and HPLC. Radiochemical purity assessed by ITLC was >96%. (99m)Tc-DTPA-GLP showed increased pancreas-to-muscle ratios, whereas (99m)Tc-DTPA showed decreased ratios at various time points. Pancreas could be visualized with (99m)Tc-DTPA-GLP in normal rat, however, (99m)Tc-DTPA has poor uptake suggesting the specificity of (99m)Tc-DTPA-GLP. Pancreas beta cell uptake could be blocked by pre-treatment with streptozotocin. DTPA-GLP showed an equal or better response in lowering the glucose levels compared to the existing GLP drug. It is feasible to use (99m)Tc-DTPA-GLP to assess pancreas beta cell receptor recognition. (99m)Tc-DTPA-GLP may be helpful in evaluating patients with diabetes, pancreatitis and pancreatic tumors.

Mechanochemical transformations in NaNH 2-MgH 2 mixtures

Mechanochemical transformations occurring during ball milling of sodium amide (NaNH 2) with magnesium hydride (MgH 2) taken in 2:3 and 2:1 molar ratios have been investigated using X-ray powder diffraction (XRD) and solid-state nuclear magnetic resonance (SSNMR) techniques. For the 2NaNH 2–3MgH 2 system the mechanochemical reaction proceeds via the formation of MgNH as an intermediate, whereas magnesium nitride (Mg 3N 2), sodium hydride (NaH) and hydrogen (∼5 wt%) form as the final products. The overall solid state reaction for this system is 2NaNH 2 + 3MgH 2 → Mg 3N 2 + 2NaH + 4H 2. However, the mechanochemical transformation of the 2NaNH 2–MgH 2 system proceeds through the reaction: 2NaNH 2 + MgH 2 → Mg(NH 2) 2 + 2NaH, without any hydrogen release. Comparison of the mechanochemical transformations with the previously studied thermochemical transformations reveals that the two approaches lead to the same final products via different reaction pathways.

Low-temperature Ammonothermal Synthesis of LaTaON2

Abstract Pure perovskite-type LaTaON2 crystal powders with high crystallinity were synthesized in supercritical ammonia using sodium amide as a flux. The synthesis temperature for this new method is 873 K, approximately 300 K lower than that for previous methods. The obtained powders have a pseudocubic lattice with a lattice constant of a = 0.4049 nm, which is in good agreement with the reported value.

Molecular Structures of THF‐Solvated Alkali‐Metal 2,2,6,6‐Tetramethylpiperidides Finally Revealed: X‐ray Crystallographic, DFT, and NMR (including DOSY) Spectroscopic Studies

The often studied THF solvates of the utility alkali-metal amides lithium and sodium 2,2,6,6-tetramethylpiperidide are shown to exist in the solid state as asymmetric cyclic dimers containing a central M(2)N(2) ring and one molecule of donor per metal to give a distorted trigonal planar metal coordination. DFT studies support these structures and confirm the asymmetry in the ring. In C(6)D(12) solution, the lithium amide displays a concentration-dependent equilibrium between a solvated and unsolvated species which have been shown by diffusion-ordered NMR spectroscopy (DOSY) to be a dimer and larger oligomer, respectively. A third species, a solvated monomer, is also present in very low concentration, as proven by spiking the NMR sample with THF. In contrast, the sodium amide displays a far simpler C(6)D(12) solution chemistry, consistent with the solid-state dimeric arrangement but with labile THF ligands.

Hydrogen Desorption from the NaNH2−MgH2 System

Ball-milled sodium amide and magnesium hydride (NaNH2:MgH2 = 1:1 molar ratio) desorbs 3.3 wt % of hydrogen between 70 and 335 °C with three desorption events. X-ray diffraction indicates that the hydrogen desorption is associated with two unidentified magnesium-containing phases. Fourier transform infrared spectroscopy indicates that these two phases correspond to an imide and nitride, respectively. Analysis of the desorption products shows a large excess of NaH and MgH2 and that optimizing the starting reagents will increase both the kinetics and the amount of hydrogen desorbed from the system below 165 °C.

Synthesis of tris(organylthioethyl)phosphines and their derivatives on the basis of the reaction of phosphine with vinyl sulfides

Phosphine generated from the red phosphorus in the system KOH-H2O-toluene adds regio- and chemoselectively to vinyl sulfides under radical initiation conditions with the formation of tris(2-organylthioethyl)phosphines, which are easily oxidized by elemental sulfur and selenium to the corresponding phosphine sulfides and phosphine selenides in 54–78% yield. The obtained adducts are split when treated with sodium amide in THF to give trivinylphosphine and trivinylphosphine chalcogenides.

On the influence of the nature of the iron(III) salt catalyst precursor for the preparation of sodium amide

Our recent experiments, for the formation of sodium amide from liquid ammonia and sodium metal, revealed the necessity to employ Fe(NO3)3*9H2O as the catalyst precursor, and not FeCl3. In the presence of FeCl3, we observed several times the ignition of the mixture during the hydrolysis, and the desired product was not obtained.