Solvent-Free Microwave Promoted [3 + 2] Cycloaddition of Alkyne-Azide in Uniform CuO Hollow Nanospheres

CuO hollow nanospheres on acetylene black (CuO/AB) have been used for the catalytic [3 + 2] cycloaddition of azides with terminal alkynes without solvent, and within 1 min under microwave irradiation. The CuO/AB was readily separated by centrifugation, and could be reused five times under the present reaction conditions without any loss of catalytic activity.     

[1, 2]-Migration Reactions Catalyzed by Gold Complexes and their Applications in Total Synthesis

The area of cascade reactions, initiated by the transition metal-catalyzed activation of π-systems and coupled with a 1,2-migration step is of considerable interest in current organic chemistry research. In this article, recent advances in the field are highlighted, focusing on gold as the activating π-acid. Cascade reactions with 1,2-shifts of alkyl groups as migrating agents are mainly presented, but also selected 1,2-aryl migrations and miscellaneous examples are depicted. With the reactions discussed, molecules of high structural complexity become readily accessible. Examples are shown where the reactions were used as the key steps of total synthesis endeavours.     

Electronic structure and bonding in the platinum–silylene complex [PtSiH2]

Relativistic ab initio molecular orbital calculations have been performed on the monoligated neutral complex [PtSiH₂] in order to investigate the nature and energetics of the interaction between the metal and SiH₂ ligand. The results suggest that the silylene ligand acts as both a σ-donor and π-acceptor but is a relatively better π-acceptor. The electronic structure of [PtSiH₂] is analyzed in detail as measured by Wiberg’s bond indices, charge distributions and orbital populations.     

The effects of 20 kHz and 500 kHz ultrasound on the corrosion of zinc precoated steels in [Cl−] [SO2−4] [HCO−3] [H2O2] electrolytes

The effects of 20 and 500 kHz ultrasound on the corrosion of precoated steels were studied by analysing the behaviour of a zinc coated steel electrode in the corrosion electrolyte [Cl^–] [SO^2– ₄] [HCO^– ₃] [H₂O₂]. The electrolyte was subjected to 20 kHz ultrasound, 500 kHz ultrasound and silent conditions. Zinc plated specimens were exposed to those solutions and growth of the corrosion products was studied by scanning electron microscopy, X-ray microanalysis and grazing incidence X-ray diffraction. Mass transfer measurements were taken on platinum macro- and microelectrodes; they highlighted a specific effect of ultrasound on the growth of zinc corrosion products depending on frequency. Ultrasound greatly influenced corrosion rates; however, the reaction sequence appeared unchanged by the use of an ultrasonic field compared to silent conditions.     

Photochemical [2+2] cycloaddition of the olefinic double bonds in the supramolecular rectangle [Ru4(η6-p-cymene)4(μ-oxalato)2(μ-4,4′-bipyridylethylene)2]4+

Self-assembly of 4,4′-bipyridylethylene (bpe) bidentate connector with the dinuclear arene ruthenium clip [Ru₂(η⁶-p-cymene)₂(μ-oxalato)Cl₂] in the presence of silver triflate affords the cationic organometallic rectangle [Ru₄(η⁶-p-cymene)₄(μ-oxalato)₂(μ-bpe)₂]⁴⁺ ([1][CF₃SO₃]₄). Upon UV irradiation of a methanol solution of [1]⁴⁺, dimerisation of the olefinic double bonds of the two parallel bpe ligands occurs, thus giving rise to the [2+2] cycloaddition derivative [Ru₄(η⁶-p-cymene)₄(μ-oxalato)₂(μ-tpcb)]⁴⁺ ([2][CF₃SO₃]₄) (tpcb = tetrakis(4-pyridyl)cyclobutane). The [2+2] photodimerisation reaction was followed by ¹H NMR spectroscopy. Moreover, the molecular structure of these two systems was deduced by one-dimensional and two-dimensional NMR experiments (¹H, ¹³C, ROESY, COSY, HSQC). These data suggest the formation of only the rctt-tetrakis(4-pyridyl)cyclobutane isomer.     

Metal-Free Electrochemical [3+2] Cycloaddition between α-Amino Carbonyls and Tosylmethyl Isocyanide en route to Substituted Imidazoles

The established strategy unveils a metal and mediator-free electrochemical [3+2] cycloaddition approach among α-amino carbonyls and tosylmethyl isocyanide (TosMIC) fabricating substituted imidazole scaffolds. Implementation of electro-redox conditions on this cycloaddition approach eliminates the essential requirement of transition metal catalysts and chemical oxidants. A wide variety of different functionalities are well tolerated under this reaction condition, contributing to the substrate scope and applicability. Several control experiments and cyclic voltammetry studies suggest an electro-oxidation triggered successive C−C and C−N bond formations followed by rapid aromatization for constructing the five-membered core structure.     

Non-Catalyzed and Pt/γ-Al2O3 Catalyzed Hydrothermal Cellulose Dissolution-Conversion: Influence of the Reaction Parameters

The dissolution of cellulose under 5 MPa of H₂ in the absence of catalyst is temperature and time dependant. The presence of Pt/γ-Al₂O₃ increases the initial rate of dissolution. The presence of H₂/Pt is essential although its exact role has not been well elucidated.     

2-[4-[2-[4-[1-(2-乙氧基)苯并咪唑-2-基]哌啶-1-基]乙基]苯基]-2-甲基丙酸的合成

以4-(2-溴乙酰基)-α,α-二甲基苯乙酸乙酯(2)为起始原料,先在酸性还原体系中还原,得到亚甲基还原产物(3)再与2-(哌啶-4-烷基)-1H-苯并咪唑(4)在有机碱的作用下进行缩合,然后在无水条件下使用氢化钠拔氢后与氯代乙基乙基醚(6)缩合得到(7),最后,将酯基水解得到2-[4-[2-[4-[1-(2-乙氧基)苯并咪唑-2-基]哌啶-1-基]乙基]苯基]-2-甲基丙酸(比拉斯汀,1)。     

Oligocyanometallic cords as building blocks in luminescent three-dimensional coordination polymers: [Ag4Cd2(tren)2(CN)6.5][Ag(CN)1.5] and [Au2Cd(tren)(CN)4]·H2O

The syntheses, structures and luminescent properties of two unusual mixed-metal coordination polymers, namely [Ag₄Cd₂(tren)₂(CN)_7.5][Ag(CN)_1.5] 1 and [Au₂Cd(tren)(CN)₄]·H₂O 2 (tren = tris(2-aminoethyl)amine), are presented. Both compounds contain abnormal metal cords of oligocyanometallic anions as building blocks wherein the d¹⁰–d¹⁰ interaction plays a crucial role in the metal–metal assembly.     

A new polymeric chain in the dihydrogendecavanadate(V)–decavanadate(V) [NH2(CH2)4]5[V10O28H2]0.5[V10O28]0.5 obtained by in situ synthesis of the organic cation

A new polymeric compound, [NH₂(CH₂)₄]₅[V₁₀O₂₈H₂]_0.5[V₁₀O₂₈]_0.5, was obtained by in situ synthesis of the organic cation from an aqueous solution of V₂O₅–HCl–NH₂(CH₂)₄NH₂. The crystal structure was solved by single-crystal X-ray diffraction. [NH₂(CH₂)₄]₅[V₁₀O₂₈H₂]_0.5[V₁₀O₂₈]_0.5 consists of dihydrogendecavanadate(V), [H₂V₁₀O₂₈]^4?, and decavanadate(V), [V₁₀O₂₈]^6?, units assembled in one-dimensional arrays by interanionic hydrogen bonds O–H?O and cation-anion N–H?O interactions. The latter involve pyrrolidinium cations, which were obtained in the compound instead of the starting butane-1,4-diamine. Pyrrolidinium cations further connect the polymeric chains into a three-dimensional network. The presence of the two types of units, [H_nV₁₀O₂₈]^(6?n)? with n = 0 and n = 2, in one compound was not yet observed and is herein reported for the first time.     

[（C2H5）N4]2{FeS4[S2CN（C2H5）2]4}的晶体和分子结构

本文报导含类立方烷型簇核Ｆｅ４Ｓ４的金硫配位化合物「（Ｃ２Ｈ５）４Ｎ２「Ｆｅ４Ｓ４」Ｓ２ＣＮ（Ｃ２Ｈ５）２」４」的合成,晶体和分子结构测定的结果。     

Chemical modification in and on single phase [NiO]0.5[Al2O3]0.5 nanopowders produces “chocolate chip-like” Nix@[NiO]0.5-x[Al2O3]0.5 nanocomposite nanopowders

Phase-pure [NiO]_0.5[Al₂O₃]_0.5 spinel nanoparticles (NPs) with limited aggregation were obtained via liquid-feed flame spray pyrolysis (LF-FSP) by combusting metalloorganic precursor solutions. Thereafter “chocolate chip-like” Ni_x[NiO_0.5-x][Al₂O₃]_0.5 nanoparticles consisting of primary [NiO_0.5-x][Al₂O₃]_0.5 particles with average particle sizes of 40-60 nm decorated with Ni metal particles (<10 nm in diameter) dispersed on the surface were synthesized by heat treating the spinel NPs at 800°C/7 h in flowing 5% H₂:N₂ 100 mL/min in a fluidized bed reactor. The synthesized materials were characterized using TEM, XRD, FTIR, and TGA/DTA. The Ni depleted areas consist primarily of γ-Al₂O₃. The Ni content (800°C) was determined by TGA to be ≈11.3 wt.% based on TGA oxidation behavior. The successful synthesis of such nanocomposites with limited aggregation on a high temperature support provides a facile route to synthesize well-defined NP catalysts. This work serves as a baseline study for an accompanying paper, wherein thin, flexible, dense films made from these same NPs are used as regenerable catalysts for carbon nanotube syntheses.     

Synthesis and proton conductivity of a new two-dimensional layered aluminophosphate [C9H14N]8[H2O]4·[Al8P12O48H4]

A new two-dimensional layered aluminophosphate [C₉H₁₄N]₈[H₂O]₄·[Al₈P₁₂O₄₈H₄] (denoted as AlPO-CJ70) has been synthesized by using N,N-dimethylbenzylamine as the template under solvothermal conditions at 403 K. Single-crystal X-ray diffraction analysis reveals that the structure of AlPO-CJ70 consists of AAAA-stacked Al₂P₃O₁₂^3 − layers made of alternating AlO₄ and PO₄ (PO₃(O) and PO₂(O)(OH)) tetrahedra, forming 1D 8-ring channels along the [100] direction. The inorganic layer exhibits a new type of 4 × 6 × 8 sheets with the Al/P ratio of 2/3. Protonated N,N-dimethylbenzylamine cations are located between the layers compensating the negative charge of the anionic framework. The existence of guest water and extensive H-bonds in the structure endows AlPO-CJ70 with proton conduction properties, as elucidated by impedance studies of the powder sample.