三溴化金催化端炔与二芳基二硒醚反应合成炔基硒醚

炔基硒醚是合成一些有机硒化合物的重要起始物。本文研究发现,在三溴化金(Au Br3)催化下,端位炔和二芳基二硒醚在弱碱(如碳酸钾)存在下反应,生成炔基芳基硒醚,产率为69%~98%;在空气参与下,于80℃下进行反应,反应条件简单,且二硒醚的两个硒原子均可以被利用。二甲基亚砜(DMSO)是合适的溶剂,在极性较小的溶剂(如甲苯、四氢呋喃)中,此反应不能进行。芳基炔(如苯乙炔、对甲基苯乙炔、对氯苯乙炔等)、烯基炔(如环己烯乙炔)和烷基炔(如1-壬炔)均能顺利进行此反应。当芳基炔苯环的间位或邻位连有取代基时,反应产率较低(69%~82%),而对位无论是连有吸电子基还是给电子基,该反应均可以得到很高的产率(95%)。     

A new synthesis of alkynyl tellurides promoted by CsOH and 4(A°) MS

The mixture of cesium hydroxide and terminal alkynes in dry DMF in the presence of 4(A°), molecular sieves was stirred for 3.0 h at room temperature under N2, then aryltellurenyl bromide in THF was added, and the reaction mixture was stirred for 2.0 h. Alkynyl tellurides were obtained in about 90% yields by flash chromatography.     

Short and efficient preparation of alkynyl selenides, sulfides and tellurides from terminal alkynes

Diphenyl diselenide reacts with terminal alkynes at room temperature in DMSO in the presence of catalytic amounts of copper iodide to give good to excellent yields of alkynyl phenyl selenides. The reaction occurs under neutral conditions and the solvent acts as the oxidant. Diphenyl disulfide and ditelluride undergo the analogous reaction, but require the presence of a weak inorganic base.     

Cryptand-22 as an efficient ligand for the copper-catalyzed cross-coupling reaction of diorgano dichalcogenides with terminal alkynes leading to the synthesis of alkynyl chalcogenides

A general and efficient method for the cross-coupling reaction of diorgano dichalcogenides with terminal alkynes using copper iodide/cryptand-22 (CuI/C22) has been developed. This protocol gave alkynyl chalcogenides in moderate to excellent yields in the presence of K₃PO₄ as the base under aerobic conditions.     

Organic Diselenides and Ditellurides: Disproportionations,Synthesis of Stannyl Selenides,Reactions with Acetylenes

The disproportionation reaction of organic diselenides 1 and ditellurides 2, the synthesis of stannyl selenides 4, and the addition reaction (palladium-catalyzed, thermal) of dialkyl diselenides to acetylenes are discussed.     

铟促进的烯丙基硒醚的合成

烯丙基溴和炔丙基溴在铟促进下与二硒化合物反应,生成烯丙基和炔丙基硒醚。反应无需严格的无水无氧条件,烯丙基溴以α-位与二硒化合物反应,产率55%～91%。     

A simple synthesis of (R)-3-aminooctanoic acid (D-BAOA) from (S)-1-octyn-3-ol

A simple substrate-controlled asymmetric synthesis of (R)-3-aminooctanoic acid (D-BAOA) is described. The present method involves the conversion of commercially available (S)-1-octyn-3-ol into the protected propargylic amine, with complete inversion of configuration, and the successive transformation of the (phenylseleno)acetylene intermediate into the Se-phenyl selenocarboxylate, which is then easily converted into the carboxylic group. The phthalimido group was eventually removed by treatment with hydrazine hydrate.     

Cesium Hydroxide–Catalyzed Reaction of Terminal Alkynes with Diarylditellurides to Synthesize Alkynyl Tellurides

In the presence of a catalytic amount of cesium hydroxide under an air atmosphere, the reaction of diarylditellurides (1.0 mmol) with terminal alkynes (2.2 mmol) at room temperature exclusively give alkynyl tellurides in good yields.     

Silylation of 1-alkynes with chlorosilanes promoted by Zn(OTf)2: an efficient way to the preparation of alkynylsilanes

Promoted by Zn(OTf)₂, a series of alkynylsilanes were prepared in high yields via direct silylation of terminal alkynes with chlorosilanes under mild conditions. It was supposed that the reaction was through the intermediate of Zn alkynilide.     

K3FeSe3 und K3Fe2Se4, zwei neue Verbindungen im System K/Fe/Se

K₃FeSe₃ and K₃Fe₂Se₄, Two New Compounds in the System K/Fe/Se The two selenides K₃FeSe₃ and K₃Fe₂Se₄ were synthesised by fusion reactions of potassium carbonate with iron and selenium in a stream of hydrogen charged with selenium at 695 °C and 710–730 °C, respectively. The crystal structures were determined by single‐crystal X‐ray diffractometer data. The atomic arrangement of K₃FeSe₃ is characterised by edge sharing [Fe₂Se₆] double tetrahedra separated by potassium ions (space group P2₁/c, Z = 4). The characteristic structural unit of the mixed‐valent compound K₃Fe₂Se₄ is a zig‐zag chain of edge‐sharing, iron‐centred selenium tetrahedra, again separated by potassium ions (space group Pnma, Z = 4).     

Cationic palladacycles as catalyst precursors for phenyl acetylene polymerization

Novel cationic palladacycles based on benzylidene-2,6-diisopropylphenylimines were prepared via C-H activation using Pd(CH₃CN)₂Cl₂ as metal precursor. The complexes were fully characterized by IR and NMR spectroscopy, mass spectrometry and elemental analysis. The cationic palladacycles were found to be active catalysts for the polymerization of phenylacetylene producing largely trans-cisoidal PPA.     

含水介质中活性金属镉促进的不对称单硒醚的合成

用Sm/CdCl~2/THF-H~2O(4/1)体系在原位获得活性金属镉,继而使二硒醚与卤代烃在室温下反应得到不对称单硒醚,该反应条件温和,中性,产率良好,提供了合成不对称单硒醚的一条新途径。     

New facts concerning the reaction of K, K(15-crown-5)2 with phenyl glycidyl ether: unexpected formation of potassium cyclopropoxide

A new mechanism of the reaction of K⁻, K⁺(15-crown-5)₂ with phenyl glycidyl ether is presented. The linear ether bond is attacked only to a small extent, if at all. As the main reaction path the oxirane bond in the β-position is cleaved, followed by the γ-elimination of potassium phenoxide and the formation of potassium cyclopropoxide. Crown ether ring opening also occurs in reactions with organometallic intermediates.     

Amine- and phosphine-free palladium(II)-catalyzed homocoupling reaction of terminal alkynes

An efficient, amine- and phosphine-free palladium(II)-catalyzed homocoupling of terminal alkynes has been developed. In the presence of PdCl₂, CuI, Me₃NO, and NaOAc, homocoupling of various terminal alkynes underwent smoothly to afford the corresponding diynes in moderate to high yields without any phosphine ligands. In contrast, the presence of a phosphine ligand (PPh₃) disfavored this palladium-catalyzed homocoupling procedure. Bases, solvents, and CuI have fundamental influence on the palladium-catalyzed homocoupling of terminal alkynes.     

Mild and efficient synthesis of propargylamines by copper-catalyzed Mannich reaction

Terminal alkynes undergo mild and efficient aminomethylation with aqueous formaldehyde and secondary amines under CuI catalysis. In most cases high to nearly quantitative yields of tertiary propargylamines are obtained in DMSO solution at room temperature. Aromatic, aliphatic and silylated acetylenes as well as alkynols can be used. Primary amines are less reactive and satisfactory yields of secondary propargylamines are obtained only with phenylacetylene.