芳基硒代酰胺与α-卤代乙酸在醇中的硒转移反应——二烷氧羰基甲基二硒醚的简便合成

芳基硒代酰胺与氯乙酸在各种醇中无催化剂下以1∶1和1∶2的比例投入, 发生硒转移反应, 不同原料投入比下的反应生成了同一种C—Se—Se—C偶联产物——具有多功能团的二烷氧羰基甲基二硒醚, 提供了一种新的合成二烷氧羰基甲基二硒醚的简便方法, 且反应具有条件温和、产率高、原料易得和选择性好等优点. 为了研究该反应机理, 选择α-溴代乙酸甲酯或α-溴代乙酸乙酯在无催化剂、中性条件下, 乙醇溶液中与苯基硒代酰胺室温下反应, 投料比为1∶1和2∶1, 结果也都生成了同一类产物二甲氧羰基甲基二硒醚或二乙氧羰基甲基二硒醚, 同时还分离得到了相应的副产物苯甲酸乙酯. 对该C—Se—Se—C偶联反应发生的可能机理作了推测.     

Cp2TiCl2/BuiMgBr/THF体系还原二芳基二硒醚

有机硒化合物具有生物活性[14],将硒基团引入到有机分子的一般方法是使亲核性的硒金属盐与亲电试剂反应 .二芳基二硒醚是制备有机硒化合物的重要中间体 .当它被还原时转化为硒负离子 ,被卤素等氧化时转化为亲电的硒试剂 .还原二硒醚通常使用ＮａＢＨ4[5 ],最近报道一些新的方法 ,如使用水合肼 /甲醇钠体系[6 ],Ｓｍ/ＨｇＣｌ2 体系[7].本文报道Ｃｐ2 ＴｉＣｌ2 /ＢｕｉＭｇＢｒ/ＴＨＦ体系还原二芳基二硒醚 .1　结果与讨论Ｃｐ2 ＴｉＣｌ2 与ＢｕｉＭｇＢｒ反应产生的钛氢化物是一种强的还原剂[8].在室温下 ,钛氢化物很容易与二硒醚反应生成…     

α-芳硒基羰基化合物的合成

茂钛硒化物分别与α－溴代酮和α－溴代酯反应生产了相应的α－硒酮和α－硒代酯，茂钛硒配合物由Ｃｐ２ＴｉＣｌ２／２ｉ－ＢｕＭｇＢｒ／ＴＨＦ体系还原二芳基二硒醚得到。     

二碘化钐促进的硒代酯的合成

用SmI2/THF/HMPA体系在室温下使二芳基二硒醚中的Se-Se键还原断裂成硒负离子物种, 继而与酸酐作用得到硒代酯, 该反应条件温和中性, 产率良好, 提供了合成硒代酯的一个新途径。     

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%)。     

Cp2TiCl2/i-BuMgBr还原断裂Se—Csp键反应研究

Cp₂TiCl₂/i-BuMgBr体系形成的钛氢化试剂与炔硒醚反应生成端炔与深蓝色钛硒化物, 后者在空气中被氧化为二醚, 与酰氯反应, 高产率地形成对应的硒代酯.     

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.     

由酮合成对称二烃基二硒醚的新方法

在正丁胺的催化下, 酮与硒氢化钠, 二硒化钠乙醇溶液通过"一锅"法反应得到了中等产率的二硒醚.     

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O,O-二烷基-Se-芳基磷酸酯的合成

在催化量氢氧化铯存在下,O,O-二烷基膦酸酯与二芳基二硒醚在DMSO中、室温、空气氛中反应,高收率得到磷酸硒酯.反应机理为氢氧化铯与O,O-二烷基膦酸酯反应生成的(RO)2P-(O)Cs+,(RO)2P-(O)Cs+亲核进攻ArSeSeAr生成磷酸硒酯和ArSe-Cs+,后者在水存在下,被氧化得到ArSeSeAr和氢氧化铯.这方法为合成磷酸硒酯提供了一条简便有效的路径.     

A Convenient Synthesis of Diacyl Selenides by Selenium Transfer Reaction of Primary Selenoamides

Aryl selenoamides are rather interesting compounds because they are versatile intermediates in organic chemistry1. It was reported that selenobenzamides have been used as selenium transfer reagents in the synthesis of alkyl diselenides from reactive halides2. We began to investigate the reactivity of arylselenoamides toward acyl chlorides and guess that this reaction would produce acyl diselenides. In surprise we could not find the diacyl diselenides (Scheme 1). Instead diacyl selenides a…     

A facile synthesis of potassium selenocarboxylates and their oxidation with XeF2 to diacyl diselenides: An X‐ray structural analysis of di(4‐methoxybenzoyl) diselenide

Several potassium selenocarboxylates were synthesized in moderate to good yields by the direct reaction of acyl chlorides with potassium selenide. The potassium salts were readily oxidized with XeF₂ to give diacyl diselenides in quantitative yields. The structure of di(4‐methoxybenzoyl) diselenide was established by X‐ray diffraction analysis. Intramolecular interactions between the carbonyl oxygen and the selenium that is connected to the opposite carbonyl group were observed. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 373–379, 1999     

Reactions of Selenobenzamide and Alkyl Halides. Synthesis of Dialkyl Selenides and Diselenides

In the absence of base, the reaction of selenooenzamide with alkyl halides gives the dialkyl diselenides as the major product. While the reaction of selenobenzamide and an alkyl halide is carried out in a 1:2 molar ratio and in the presence of strong base, the dialkyl selenides predominate.     

Reductive cleavage of the Se–Se bond in diselenides by the Sm/HgCl2 system: Formation and reactions of samarium selenolates

Treatment of diaryl diselenides and dialkyl diselenides with metallic samarium and mercury (II) chloride in tetrahydrofuran conveniently gave samarium arylselenolates and alkylselenolates. These “living” species reacted with acyl chlorides, acid anhydrides, methyl chloroformate, organic halides, epoxides, α,β‐unsaturated esters, and an α,β‐unsaturated nitrile to afford selenoesters, selenoformates, and unsymmetrical selenides in good yields under mild and neutral condition. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 203–208, 1999     

Indium(I) iodide-promoted cleavage of diaryl diselenides and disulfides and subsequent condensation with alkyl or acyl halides. One-pot efficient synthesis of diorganyl selenides, sulfides, selenoesters, and thioesters

Diphenyl diselenides and disulfides undergo facile cleavages by indium(I) iodide and the corresponding generated selenate and thiolate anions condense in situ with alkyl or acyl halides present in the reaction mixture. Thus, a simple, efficient, and general procedure has been developed for the synthesis of unsymmetrical diorganyl selenides, sulfides (thioethers), selenoesters, and thioesters by this one-pot reaction at room temperature.     

Efficient synthesis of diorganyl selenides via cleavage of Se-Se bond of diselenides by indium(III) catalyst and zinc

A simple and efficient procedure for the synthesis of unsymmetrical diorganyl selenides from an one-pot indium(III) catalyzed procedure, in the presence of zinc, has been developed. Various organic halides and even the unreactive organic chlorides underwent the reaction efficiently. Also diaryl and dialkyl diselenides underwent the coupling reaction.     

Synthesis and reactions of the optically active selenols derived from monoterpenes

A convenient methodology for the synthesis of optically active selenols, derived from p-menthane, carane, and pinane, is described. The selenols were oxidized with air to give the optically active diselenides, and were also converted into the corresponding allylic selenides via reaction with Z- and E-cinnamyl, geranyl, and neryl chlorides. Oxidation of the allylic selenides with mCPBA gave the optically active alcohols via [2,3]-sigmatropic rearrangement of the in situ generated allylic selenoxides.     

Ruthenium(III) chloride catalyzed efficient synthesis of unsymmetrical diorganyl selenides via cleavage of dibenzyl and diphenyl diselenides in the presence of zinc

[equation: see text] An efficient one-pot route to unsymmetrical diorganyl selenides has been developed by ruthenium(III) chloride catalyzed reactions of dibenzyl or diphenyl diselenides with alkyl halides in the presence of zinc. Organic iodides, bromides, and activated chlorides underwent the reactions efficiently. Unreactive organic chlorides also underwent the same type of selenation with sodium bromide as the additive.