氢氧化铯促进下硒、端炔及卤代烃反应合成炔硒醚

DMF作溶剂, 4Å分子筛存在下, 将端炔、CsOH、硒粉在室温搅拌2 h, 然后加入溴代烃或二芳基碘盐, 在室温下搅拌20 h, 得炔硒醚, 收率约60%. 反应机理为端炔与氢氧化铯作用形成炔化铯, 然后元素硒进行C—Cs键插入形成炔硒化铯, 炔硒化铯对溴代烃或二芳基碘盐进行亲核取代得到相应的炔硒醚     

氢氧化铯促进下硒、端炔及二芳基碘盐反应合成炔基芳基硒醚

以N,N-二甲基甲酰胺(DMF)作溶剂, 在4 Å分子筛存在及氮气保护下, 将端炔、CsOH、硒粉在室温搅拌2 h, 然后加入二芳基碘盐, 在0 ℃搅拌30 h, 得炔硒醚, 收率约60%.     

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%)。     

原子经济反应:氢氧化铯催化下二硒醚与端炔反应合成炔硒醚

氢氧化铯是无机超强碱,它能夺去端炔上的氢而产生稳定炔负离子,这种炔负离子与亲电的酮、醛反应生成相应的炔醇,但是与亲电的杂原子反应形成碳杂键的研究尚未见报道,碳杂键的形成是合成杂原子有机化合物的主要途径,所以研究无机超强碱催化下的碳杂键形成反应,有可能开辟-个合成杂原子有机化合物的新领域,不论在理论上还是在应用上都具有重要意义。     

氢氧化铯促进下炔基碘的合成

端炔与氢氧化铯在无水THF中于室温反应3h后与碘作用合成了7个炔基碘,收率78%~91%。其结构经1HNMR,13CNMR和MS确认。     

氢氧化铯促进二烷基二硒醚的合成

氢氧化铯存在下,以无水N,N'-二甲基甲酰胺(DMF)作溶剂,在室温下水合肼还原硒形成的二硒化铯与含官能团的卤代烃或磺酸酯反应,高收率地形成对应的二烷基二硒醚.     

氢氧化铯催化端炔氢硒化:高立体区域选择性合成(E)-1-芳硒基烯烃

在催化量氢氧化铯存在下,端炔与硒酚在N,N-二甲基甲酰胺(DMF)中、室温、氮气保护下,发生亲核加成反应,高收率、高立体选择性合成一系列(E)-1-芳硒基烯.反应机理为氢氧化铯与硒酚反应产生的芳硒化铯,随后对端炔进行亲核加成,形成的烯基负离子水解得到产物.这方法为不活泼端炔氢硒化提供了一条新的和简便途径.     

氢氧化铯催化下,二芳基二硒醚对端炔的加成:高选择性合成(Z)-1,2-二芳硒基烯

氢氧化铯催化下,以商业THF作溶剂,端炔与二芳基二硒醚在氮气保护下,25或35℃时反应,立体选择地生成(Z)-1,2-二芳硒基烯.     

Chemo- and Regioselective Dimerization of Terminal Alkynes Promoted by Methylaluminoxane

Methylalumoxane (MAO) was found to be an active catalytic precursor for the chemo- and regioselective dimerization of a wide range of aryl- and alkyl-substituted terminal alkynes yielding the corresponding geminal dimers A. For an olefin-functionalized terminal alkyne (RC&tbd1;CH, R = MeC=CH(2)), the geminal dimer undergoes an intermolecular [4 + 2] cycloaddition forming compound B.     

Coupling of Terminal Alkynes Promoted by Organic Polyvalent Iodine Compounds

Terminal alkynes couple smoothly in the presence of Phl(OAc)₂ or Phl(OH)OTs, catalytic amount of Cul and base, affording conjugated diynes.     

Photoinitiated anti-Hydropentafluorosulfanylation of Terminal Alkynes

A photoinitiated anti-hydropentafluorosulfanylation of terminal alkynes using SF₅Cl and (TMS)₃SiH as the hydrogen atom donor is reported. This transformation generates selectively (Z)-(1-alken-1-yl)pentafluoro-λ⁶-sulfanes (Z:E : >85:15), thus allowing the preparation of this previously unknown geometrical isomer. DFT calculations highlight that the selectivity is due to the intrinsic preference of SF₅-substituted vinylic radicals to adopt a cis geometry, and to increased steric contacts during the transition structures leading to the minor (E)-products.     

Copper‐Promoted Oxidative Coupling of Enamides and Alkynes for the Synthesis of Substituted Pyrroles

An efficient copper‐promoted oxidative coupling of enamides with alkynes has been developed for the synthesis of substituted pyrroles. The reaction proceeded through C?H and N?H bond functionalization of enamides under mild conditions.     

Ligand-Free Synthesis of 1,4-Disubstituted-1,3-diynes by Iron/Copper Cocatalyzed Homocoupling of Terminal Alkynes

A simple and efficient protocol for Fe/Cu cocatalyzed oxidative homocoupling reaction of terminal alkynes to symmetrical 1,4‐disubstituted‐1,3‐diynes was presented. The results showed that both CuBr and FeCl₃ played crucial roles in the reaction. It is noteworthy that this protocol employs mild, efficient, aerobic and ligand free conditions. The alkynes, including aromatic, heteroaromatic and aliphatic alkynes, were transformed into the corresponding 1,3‐diynes in good to excellent yields.     

Highly Selective Synthesis of Acetylenic Alcohols Promoted by Metallic Dysprosium in the Presence of Mercuric Chloride

Promoted by metallic dysprosium, carbonyl compounds react smoothly with propargyl bromide to afford the corresponding homopropargylic alcohols in good to excellent yields without observation of allenic alcohols. In addition, this reaction is regioselective and chemoselective.     

Modified Glaser Reaction of Terminal Alkynes on KF/Alumina

Summary. A variety of 1,3-diyne compounds are prepared in a solvent-free reaction on KF/alumina in the presence of catalytic amounts of Cu(OAc)₂·H₂O with up to 96% yields at room temperature.