Metal-free one-pot three-step process for the direct conversion of aryl alkynes into secondary amines with TfOH/B2(OH)4

A metal-free one-pot synthesis of secondary amines from aryl alkynes via hydration-condensation-reduction three-step process in the presence of TfOH and B₂(OH)₄ has been developed. A series of secondary amines were obtained with good functional group tolerance and satisfied yields.     

Mg-Li合金表面芳烃的还原

利用浸渍法研究了不同有机物体系(芳烃类)在Mg-Li合金表面的还原反应. 通过X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)及扫描电子显微镜(SEM)等分析测试手段, 考察了不同的反应物及其不同含量对有机还原反应的影响. 结果表明, 当反应物苯、异丙醇和氯化铵体积比为3∶2∶1时, 苯在Mg-Li合金表面被还原, 镁被氧化为Mg(OH)2并可能与有机物通过共价键形成类似于JPCDS标准卡片中复杂结构的C4H6MgO4, 且在合金表面生长出棒状、针状等物质.     

Novel perfluoroalkylated oligo(oxyethylene) methyl ethers with high hemocompatibility and excellent co-emulsifying properties for potential biomedical uses

Two series of novel perfluoroalkylated amphiphilic compounds were synthesized from monomethyl ethers of mono-, di- and tri-(oxyethylene) glycols. The first series CH₃(OCH₂CH₂)_nOCH₂CH(OH)CH₂-CF₂(CF₂CF₂)_nCF₃ (n = 1-3) bearing the hydroxy group at the spacer between hydrophilic and hydrophobic parts was prepared by the reactions of the monomethyl ethers with 2-(perfluoroalkylmethyl)oxiranes in 76-97% yields. The second series CH₃(OCH₂CH₂)_nOCH₂CH₂CH₂-CF₂(CF₂CF₂)_nCF₃ (n = 1-3) possessing the non-hydroxylated spacer was synthesized from allyl methyl ethers of oligo(oxyethylene) glycols using radical additions of perfluoroalkyl iodides and subsequent selective reductions of the C-I bond in the adducts in overall yields of 23-69%. Some of the novel amphiphilic compounds displayed very low hemolytic activity to erythrocytes and excellent co-emulsifying properties on testing on perfluorodecalin/Pluronic F-68 microemulsions. 1-O-(2-Hydroxy-4,4,5,5,6,6,7,7,8,8,9,9,9-tridecafluorononyl)-d-xylitol was prepared by a novelized synthesis and employed as a standard compound in the testing.     

Penta- and heptacoordinated tin(IV) compounds derived from pyridine Schiff bases and 2-pyridine carboxylate: Synthesis and structural characterization

The synthesis of the Sn(IV)-complexed, Schiff base derivatives 1a-1l, prepared in one pot by the reaction of 2-amino-4-R-phenol (R = H, Me, Cl, NO₂), 2-pyridinecarboxaldehyde, 2-picolinic acid and dimethyl-, dibutyl-, and diphenyltin oxides, is described. The complexes were characterized by IR, MS, ¹H, ¹³C, ¹¹⁹Sn NMR. Suitable crystals of 1e and 1h enabled us to use X-ray diffraction to determine their molecular structures, which exhibited pentagonal-bipyramidal geometries where the butyl groups occupied the axial positions whereas the nitrogen and the oxygen atoms occupied the equatorial positions. The reaction of the Schiff base 2 with dibutyltin oxide led to the pentacoordinated complex, 2h, through the addition of methanol to the CN bond. An unusual reduction-oxidation reaction took place by the reaction of 2-amino-4-nitro-phenol, dibutyltin oxide and 2-pyridinecarboxaldehyde, which produced the corresponding amine, 3h, and the amide, 4h, tin(IV) derivatives. Both structures were established by X-ray crystallography and exhibited a distorted, bipyramidal trigonal (BPT) geometry.     

Transfer hydrogenation of olefins catalysed by nickel nanoparticles

Nickel nanoparticles have been found to effectively catalyse the hydrogen-transfer reduction of a variety of non-functionalised and functionalised olefins using 2-propanol as the hydrogen donor. The heterogeneous process has been shown to be highly chemoselective for certain substrates, with all the corresponding alkanes being obtained in high yields. A synthesis of the natural dihydrostilbene brittonin A is also reported based on the use of nickel nanoparticles.     

Synthesis of imatinib: a convergent approach revisited

Abstract  A classical convergent approach for the synthesis of the anticancer drug imatinib has been substantially improved. Imatinib was assembled by coupling the amine and carboxylic acid precursors by using N,N′-carbonyldiimidazole (CDI) as a condensing agent. Both intermediates have been synthesized by novel efficient methods. Graphical abstract        

Straightforward selective preparation of nitro- or amino-indoles from 2-halonitroanilines and alkynes. First synthesis of 7-amino-5-nitroindoles

A one-pot selective synthesis of 2-substituted C5-, C6-, and C7-nitro- or amino-indoles has been developed from 2-halonitroanilines. These two types of nitrogen-substituted indoles have been selectively obtained by only varying the solvent used in the tandem Sonogashira coupling/heteroannulation reaction. Moreover, from commercially available 2-bromo-4,6-dinitroaniline an unprecedented in situ selective reduction of one of the nitro groups has allowed the synthesis of new 7-amino-5-nitro-2-substituted indoles.     

A simple, efficient, and selective deuteration via a flow chemistry approach

A simple and efficient deuteration methodology has been established for a wide variety of substrates using a continuous flow hydrogenation reactor. The described procedure is many times faster (1 mg min⁻¹) compared to literature methods and the purity of the crude product can be as high as 99%. The deuterium source is D₂O, the consumption of which is very low.     

Some critical point theorems and their applications to periodic solution for second order Hamiltonian systems

Some critical point theorems without the compactness assumptions are obtained by the reduction method, the perturbation argument and the least action principle. As applications, some existence results of periodic solutions are obtained for nonautonomous second order Hamiltonian systems, which unify and generalize some recent corresponding results.