15785-07-6Relevant articles and documents
Stereoelectronic factors in bridgehead C-H bond insertion: Studies toward the total synthesis of maoecrystal v
Jansone-Popova, Santa,May, Jeremy A.
, p. 3734 - 3747 (2016)
A strategy for the total synthesis of maoecrystal V is presented. The key interior vicinal quaternary carbon centers will be formed via sequential bridgehead C-H bond insertion and enolate functionalization. Studies herein validate the C-H bond insertion as feasible in model studies, though there are significant effects on the selectivity for the bridgehead position from neighboring groups. Both inductive electron withdrawing elements and sterics play a role in deactivating that position, with the former having a greater effect. Forming the second quaternary carbon is possible via enolate acylation and alkylation. Lastly, an approach to synthesize the cyclohexenone ring of maoecrystal V is described.
Luminescent CeCl3 nanoparticles by Tris(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)cerium diglyme photolysis in chlorinated solvents
Giuffrida, Salvatore,Condorelli, Guglielmo G.,Costanzo, Lucia L.,Ventimiglia, Giorgio,Favazza, Maria,Petralia, Salvatore,L. Fragalà, Ignazio
, p. 4043 - 4052 (2006)
Irradiation of [Ce(hfac)3(diglyme)] (hfac = 1,1,1,5,5,5-hexafluoro-2,4-pentanedionato and diglyme (DG) = 2,5,8,11,14-pentaoxapentadecane) in chlorinated solvents (CH2Cl2, CCl4) with UV light led to luminescent colloidal CeCl3 that was characterized by transmission electron microscopy (TEM) analysis. When a substrate, quartz or silicon was present in the reaction cell, photoluminescent films were obtained, containing either pure CeCl3 or mixtures of CeCl3, CeF3 and CeOx in function of the experimental parameters of irradiation. Nanostructured and luminescent pure CeCl3 films were obtained by irradiation of the cerium complex in CCl4 at high intensity light for a few minutes. The films were characterized by X-ray diffraction (XRD), Energy dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS), TEM, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The kinetics of the [Ce(hfac)3(diglyme)] solution photodegradation, followed by UV spectrophotometry and spectrofluorimetry, pointed to CeCl3 formation by a solvent-initiated reaction, whereas the other inorganic compounds were the products of side reactions.
CeO2 nanorods and gold nanocrystals supported on CeO2 nanorods as catalyst
Huang,Wu,Zhu,Gao,Zhu,Yan,Huang,Wu,Song
, p. 19169 - 19174 (2005)
The formation mechanism of uniform CeO2 structure at the nanometer scale via a wet-chemical reaction is of great interest in fundamental study as well as a variety of applications. In this work, large-scale well-crystallized CeO2 nanorods with uniform diameters in the range of 20-30 nm and lengths up to tens of micrometers are first synthesized through a hydrothermal synthetic route in 5 M KOH solution at 180 ?°C for 45 h without any templates and surfactants. The nanorod formation involves dehydration of CeO2 nanoparticles and orientation growth along the ???110??? direction in KOH solution. Subsequently, gold nanoparticles with crystallite sizes between 10 and 20 nm are loaded on the surface of CeO 2 nanorods using HAuCl4 solution as the gold source and NaBH4 solution as a reducing agent. The synthesized Au/CeO 2 nanorods demonstrate a higher catalytic activity in CO oxidation than the pure CeO2 nanorods. ? 2005 American Chemical Society.
Moosath, S. S.,Rao, M. R. A.
, p. 213 - 219 (1956)
Refractive indices and molar refractivities of molten rare-earth trichlorides and their mixtures with alkali chlorides
Kochedykov, Victor A.,Khokhlov, Vladimir A.
, p. 44 - 51 (2017)
New experimental data on the refractive indices and molar refractivities of molten cerium, neodymium, samarium, and gadolinium trichlorides and CeCl3-ACl, SmCl3-ACl, Gd3Cl-ACl (A = Na, 0.5Na-0.5K, K, and Cs) mixtures depending on the temperature and composition are reported. It is shown that the relative deviations of the molar refractivity of mixtures from their magnitudes inherent to the hypothetic ideal solutions increase as the radii of alkali metal cations rises. The difference in variation of the Ln3+-ions electron polarizability with the atomic number or ionic radius is revealed for cerium and yttrium subgroups of the lanthanide row.
Oxa-adamantyl cannabinoids
Ho, Thanh C.,Tius, Marcus A.,Nikas, Spyros P.,Tran, Ngan K.,Tong, Fei,Zhou, Han,Zvonok, Nikolai,Makriyannis, Alexandros
, (2021)
As a continuation of earlier work on classical cannabinoids bearing bulky side chains we report here the design, synthesis, and biological evaluation of 3′-functionalized oxa-adamantyl cannabinoids as a novel class of cannabinergic ligands. Key synthetic steps involve nucleophilic addition/transannular cyclization of aryllithium to epoxyketone in the presence of cerium chloride and stereoselective construction of the tricyclic cannabinoid nucleus. The synthesis of the oxa-adamantyl cannabinoids is convenient, and amenable to scale up allowing the preparation of these analogs in sufficient quantities for detailed in vitro evaluation. The novel oxa-adamantyl cannabinoids reported here were found to be high affinity ligands for the CB1 and CB2 cannabinoid receptors. In the cyclase assay these compounds were found to behave as potent and efficacious CB1 receptor agonists. Isothiocyanate analog AM10504 is capable of irreversibly labeling both the CB1 and CB2 receptors.
Synthesis and Characterization of the Cerium(III) UV-Emitting 2D-Coordination Polymer 2 ∞[Ce2Cl6(4, 4′-bipyridine)4]·py
Matthes, Philipp R.,Müller-Buschbaum, Klaus
, p. 2847 - 2851 (2014)
The 2D-coordination polymer 2 ∞[Ce2Cl6(bipy)4]·py (bipy = 4, 4′-bipyridine) shows a 5d-4f centered emission in the soft UV-B region. It was synthesized via the reaction of anhydrous CeCl3 and 4, 4′-bipyridine in pyridine under solvothermal conditions. The two-dimensional sheet structure consisting of 4, 4′-bipyridine coordinated Ce2Cl6 dimers closes the gap between the known lanthanum 3 ∞[La2Cl6(bipy)5]·4bipy framework and the 2D networks of the formula 2 ∞[Ln 2Cl6(bipy)3]·2bipy from praseodymium on. They differ in the number of coordinating bipy linkers, which decreases along La > Ce > Pr, with the remarkable observation that lanthanum, cerium, and praseodymium exhibit different network constitutions. The structure of 2 ∞[Ce2Cl6(bipy)4]·py exhibits a cem topology constituted of double strands, which are diagonally linked by 4, 4′-bipyridine forming trapezoid cavities in-between the strands. The cavities contain intercalated pyridine molecules.
Bis(pentamethylcyclopentadienyl) complexes of cerium(III). Crystal structure of (C5Me5)2CeCH(SiMe3)2
Heeres, Hero J.,Renkema, Jaap,Booij, Martin,Meetsma, Auke,Teuben, Jan H.
, p. 2495 - 2502 (1988)
CeCl3·xTHF (1 1 in THF forming Cp*2CeCl2Li(THF)2.5 (1). The coordinated THF can easily be displaced by DME to form Cp*2CeCl2Li(DME) (2). When 1 is heated to 250°C (0.01 mmHg), (Cp*2CeCl)n (4) sublimes. A number of adducts, Cp*2CeCl·Ln (5, L = THF, n = 1; 6, L = t-BuCN, n = 2), are accessible starting from 4. Metathesis of 4 with LiCH(SiMe3)2 and NaN(SiMe3)2 in toluene gives Cp*2CeCH(SiMe3)2 (8) and Cp*2CeN(SiMe3)2 (11), respectively. Compound 8 reacts with LiCl in the presence of TMEDA to form Cp*2CeCl2Li(TMEDA)2 (3) and LiCH(SiMe3)2. Addition of t-BuCN to 8 affords the adduct Cp*2CeCH(SiMe3)2-t-BuCN (9). (Cp*2CeH)2 (10) can be made by hydrogenolysis of 8 under mild conditions. Cp*2CeNH-t-Bu-NH2-t-Bu (12) and also 11 are prepared by the reaction of 8 with the corresponding amines. 8 crystallizes in the monoclinic space group P21/n with a = 11.061 (3) A?, b = 23.46 (1) A?, c = 11.692 (5) A?, and β = 102.99 (2)° (Z = 4). Least-squares refinement leads to a final R (based on F) of 0.038 for 5534 independent reflections. The molecular structure consists of monomeric Cp*2CeCH(SiMe3)2 units with a bent sandwich configuration. The average (ring centroid)-Ce-(ring centroid) angle is 134°. The CH(SiMe3)2 fragment is coordinated in a highly unsymmetrical fashion with a Ce-C σ-bond distance of 2.536 (5) A?.
Design of a Br?nsted acid with two different acidic sites: Synthesis and application of aryl phosphinic acid-phosphoric acid as a Br?nsted acid catalyst
Momiyama,Narumi,Terada
, p. 16976 - 16979 (2015)
A Br?nsted acid with two different acidic sites, aryl phosphinic acid-phosphoric acid, has been synthesized. Its catalytic performance was assessed in the hetero-Diels-Alder reaction of aldehyde hydrates with Danishefsky's diene, achieving high reaction efficiency.
The first structure with isolated carbon-centered tetrahedra of rare-earth metals - The new compound Ce4CCl8
Schaloske, Manuel C.,Kienle, Lorenz,Hoch, Constantin,Mattausch, Hansjurgen,Kremer, Reinhard K.,Simon, Arndt
, p. 1023 - 1029 (2009)
Ce4CCl8 is prepared by heating stoichiometric mixtures of cerium, CeCl3 and carbon in sealed tantalum capsules at 820 °C. It forms black polyhedral, in fragments transparent orange to red and moisture-sensitive crystals [s
Seifert, H. J.,Sandrock, J.,Thiel, G.
, p. 1309 - 1318 (1986)
Two Series of New Volatile Rare-Earth Metal Tris(guanidinates) and Tris(amidinates)
Tutacz, Peter,Harmgarth, Nicole,Z?rner, Florian,Liebing, Phil,Hilfert, Liane,Engelhardt, Felix,Busse, Sabine,Edelmann, Frank T.
, p. 1653 - 1659 (2018/10/31)
Two series of new volatile, homoleptic lanthanide(III) tris(guanidinate) and tris(amidinate) complexes were synthesized and fully characterized. Treatment of anhydrous rare-earth metal(III) chlorides, LnCl3, with three equiv. of the aziridine-derived lithium guanidinate Li[c-C2H4NC(NiPr)2] (3) afforded the new homoleptic tris(guanidinate) complexes [c-C2H4NC(NiPr)2]3Ln (4) (Ln = Sc, Pr, Nd, Sm, Eu, Ho, Tm) in good yields (68–80 %). In a similar manner, the homoleptic tris(amidinate) complexes [iPrC(NiPr)2]3Ln (6) Ln = Sc, Ce, Pr, Nd, Tb, Dy, Er, Yb) were prepared from LnCl3 and the all-isopropyl-substituted lithium amidinate Li[iPrC(NiPr)2] (5) in a molar ratio of 1:3. Variable-temperature 1H NMR studies of the paramagnetic derivatives 4Pr–4Tm revealed Curie-type behavior. 1H NMR spectroscopic data of complexes 6 indicated severe steric crowding due to the presence of nine isopropyl groups in these molecules. The molecular and crystal structures of eight title compounds (4Sc, 4Pr, 4Nd, 4Sm, 4Eu, 4Ho, 4Tm, and 6Er) were determined through single-crystal X-ray diffraction studies. All complexes 4 exhibit similar molecular structures, comprising distorted octahedral molecular structures with small bite angles. Sublimation temperatures of 4 at 0.05 mbar were determined to be in the range between 151 °C (4Eu) and 194 °C (4Tm), whereas the complexes 6 sublime in the temperature range between 140 °C (6Sc) and 180 °C (6Ce), so that the use of these precursors in future ALD or CVD studies appears feasible.
