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…     

2，2’-二硒并烟酸及其叔丁基酯的合成和结构

本文以2-氯烟酸为原料合成了2,2’-二硒并烟酸叔丁基酯（1）及2,2’-二硒并烟酸（2）,化合物1和2的结构分别用^1HNMR,^13C NMR,^77Se NMR,元素分析和X-射线单晶结构测定技术进行了表征。在化合物1和2的晶体结构中,吡啶环和2个硒原子处于同一平面,这一结果与已报道的芳基二硒醚化合物的晶体结构完全不同。     

叔丁基过氧化氢介导的磷酸硒酯合成

磷酸硒酯化合物广泛应用于有机合成和药物发现等相关领域.因此,开发高效简便合成该类化合物的新方法受到化学家的广泛关注.报道了一种以叔丁基过氧化氢(TBHP)为氧化剂,在温和的反应条件下实现了亚磷酸酯和二硒醚偶联反应制备硒代磷酸酯方法.与现有方法相比,该方法具有条件温和、底物适用范围广泛、产率高、且不需过渡金属和强碱等优点...     

二碘化钐诱导的芳族二硒醚Se—Se键还原断裂导致芳基硒负离子:β-硒代酯(腈)的制备

报导了芳族二硒醚在SmI_2作用下,Se—Se键还原断裂成硒负离子。再与α,β-不饱和酯(腈)发生Michael加成反应,得到β-硒代酯(腈)。     

烯烃自由基胺硒化:β-氨基硒醚的简易合成（英文）

发展了一种高效的烯烃、二芳基二硒醚和烷基胺的分子间胺硒化策略,在铜盐和高价碘试剂条件下,以较高产率获得一系列的β-氨基硒化物.初步的实验结果表明,反应涉及活性硒自由基中间体,并提出了自由基反应机理.     

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.     

硒催化反应最新研究进展

价廉易得的非金属硒作催化剂不但具有良好的催化活化CO的性能及反应过程相转移催化特性, 而且能循环使用. 用Se/CO催化体系替代贵金属催化羰基化法及剧毒的光气法进行羰基化反应及用Se/CO/H2O催化体系进行高选择性的还原反应, 具有反应条件温和、原子经济性高、成本低、环境友好、路线简短、后处理方便等优点, 因而引起人们的广泛关注. 概述了近几年来硒催化羰基化反应和硒催化选择性还原反应的最新研究进展, 并对硒催化反应的发展趋势进行了展望.     

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.     

HPLC-DRC-ICP-MS测定富硒蔬菜中的硒形态

建立了高效液相色谱-动态反应池-电感耦合等离子体质谱(HPLC-DRC-ICP-MS)联用测定硒代胱氨酸(SeCys2)、甲基硒代半光氨酸(MeSeCys)、亚硒酸盐(SeIV)、硒代蛋氨酸(SeMet)和硒酸盐(SeVI)的方法。样品通过胃蛋白酶提取,采用Hamilton PRP X-100色谱柱(250 mm×4.6 mm,10μm),使用5 mmol/L的柠檬酸溶液(pH 4.7)作为流动相,在10 min内可以完全分离5种硒形态。在80Se质量数下,采用甲烷作为DRC反应气,可有效消除40Ar40Ar+对80Se的干扰,提高检测灵敏度。电感耦合等离子体质谱(ICP-MS)检测,各硒形态的线性相关系数均大于0.9990,Se(IV)、Se(VI)、SeMet、SeCys2、MeSeCys的定量限分别为5,10,10,5,5μg/kg,5种硒形态的加标回收率在80.1%～99.2%之间,可满足蔬菜中硒形态定量分析。     

Convenient route to dialkyl diselenides from alkyl tosylates. Synthesis of di(cis-myrtanyl) diselenide

A one-step method for the synthesis of dialkyl diselenides, by reaction of alkyl tosylates with sodium diselenide is described. Three variants of the synthesis, using as an example the preparation of optically active di(cis-myrtanyl) diselenide, are compared.     

A Convenient Synthesis of 4,4′-Dimethylaminodiphenyl Diselenide and 4,4′-Dinitrodiphenyl Diselenide

A simple, rapid and efficient synthesis of 4,4′-dimethylamino-diphenyl diselenide 1 and 4,4′-dinitrodiphenyl diselenide 2 is described. The method consists of the reductive cleavage of the Se-CN linkage in the corresponding aryl selenocyanates by sodium borohydride followed by air oxidation of the resulting seleno-lates. The diselenides 1 and 2 are readily obtained in a state of high purity, in 89 and 80% yield, respectively.     

Preparation of bis(2-pyridyl) diselenide derivatives: Synthesis of selenazolo[5,4-b]pyridines and unsymmetrical diorganyl selenides,and evaluation of antioxidant and anticholinesterasic activities

We describe here an alternative method to prepare bis(2-pyridyl) diselenide derivatives using reduced selenium species, generated in situ, and different 2-chloropyridines promoted by p-TSOH in PEG-400 as solvent. This is a straightforward protocol to prepare bis(3-amino-2-pyridyl) diselenides unprecedented to date. Still, this article describe the employment of synthesized bis(3-amino-2-pyridyl) diselenide and a diverse array of aryl aldehydes to afford the corresponding 2-aryl-selenazolo[5,4-b]pyridines in satisfactory yields and, in a short reaction time under basic condition. Furthermore, when the bis(3-amino-2-pyridyl) diselenide reacted with aliphatic halides, in the presence of NaBH₄, a wide range of unsymmetrical diorganyl selenides was obtained. To complete this investigation the bis(3-amino-2-pyridyl) diselenide was evaluated for its inhibitory effect on the acetylcholinesterase (AChE) activity and free radical-scavenging capacity. Results demonstrated that this compound was antioxidant and inhibitor of the AChE activity, being a promising therapeutic agent for the treatment of Alzheimer’s disease and other neurodegenerative disorders.     

Lithium diselenide in aprotic medium - a convenient reagent for synthesis of organic diselenides

The reduction of selenium with lithium in THF in the presence of diphenylacetylene as a catalyst afforded lithium diselenide, which reacted with electrophiles giving alkyl or aryl diselenides 1 - 3 and selenides 4, as by-products. The useful method for preparation of diselenides based on this reaction was elaborated.     

Rhodium-catalyzed regio- and stereoselective 1-seleno-2-thiolation of 1-alkynes

Rhodium complex RhH(PPh(3))(4) and 1,1'-bis(diphenylphosphino)ferrocene catalyze the regio- and stereoselective additions of diaryl disulfides and diaryl diselenides to 1-alkynes giving (Z)-1-arylseleno-2-arylthio-1-alkenes. The catalyst promotes the addition reaction of dibutyl disulfide and dibutyl diselenide to 1-octyne with a similar selectivity giving (Z)-1-butylseleno-2-butylthio-1-octene but with a lower catalytic activity. The same product is obtained with a higher yield, when excess dibutyl disulfide is used against dibutyl diselenide in the presence of RhH(PPh(3))(4) and 1,4-diphenylphosphinobutane.     

Aromatic Ring Strain in Arylselenenyl Bromides: Role in Facile Synthesis of Selenenate Esters via Intramolecular Cyclization

The synthesis and reactivity of 2,6‐disubstituted arylselenium compounds derived from 2‐bromo‐5‐tert‐butylisophthalic acid ( 43 ) are described. The syntheses of bis(5‐tert‐butylisophthalic acid dimethyl ester)diselenide ( 46 ) and bis(5‐tert‐butylisophthalic acid diisopropyl ester)diselenide ( 47 ) have been achieved by the reaction of the corresponding ester precursors with disodium diselenide. Reduction of diselenide 46 with lithium aluminum hydride affords 2,2′‐bis(5‐tert‐butylbenzene‐1,3‐dimethanol)diselenide ( 53 ). Diselenides 46 and 47 exhibit intramolecular Se???O interaction. Compound 53 does not show any intramolecular Se???O interaction. The anomalous Se???O nonbonded coordination observed in the single‐crystal X‐ray structures of compounds 46 , 47 and 53 is compared and contrasted. The corresponding selenenyl bromides 54 and 55 , derived from the reaction of diselenides 46 and 47 with bromine, are quite stable in the solid state. However, they undergo hydrolysis and subsequent intramolecular cyclization upon heating or after having been kept in solution over a period of time to give the corresponding selenenate esters 56 and 57 . The X‐ray crystallographic study and density functional theory calculations on 54 at the B3LYP/6‐31G(d) level of theory indicate a significant distortion in planarity of the aromatic ring. Glutathione peroxidase‐like activities of diselenides 46 and 47 and their selenenate esters 56 and 57 have been studied both by thiophenol and bioassay methods. The very low glutathione peroxidase‐like activity of the diselenides ( 46 and 47 ) and their selenenate esters ( 56 and 57 ) in the thiophenol assay is attributed to the presence of the relatively strong Se???O intramolecular interaction in the selenenyl sulfide intermediates. The interaction retards the catalytic activity through both thiol exchange and an intramolecular cyclization reaction.     

The Synthesis of 1-Phenoxy-3- Arylseleno-2-Propanol

A general and efficient synthetic method of 1-phenoxy-3-arylseleno-2-propanol by reducing diary1 diselenides with sodium borohydride in basic environment and their reaction with epoxypropoxyphenols are described.     

Synthesis of 4‐(Phenylamino)quinazoline‐2(1H)‐selones and Diselenides from Isoselenocyanates: Dimroth Rearrangement of an Intermediate

The reaction of anthranilonitriles 8 with phenyl isoselenocyanates ( 1a ) in dry pyridine under reflux gave 4‐(phenylamino)quinazoline‐2(1H)‐selones 9 (Scheme 2). They are easily oxidized and converted to diselenides of type 11 . The analogous reaction of 8a with phenyl isothiocyanate ( 1b ) yielded the quinazoline‐2(1H)‐thione 10 (Scheme 2). A reaction mechanism via a Dimroth rearrangement of the primarily formed intermediate is presented in Scheme 3. The molecular structures of 10 and 11a have been established by X‐ray crystallography. Unexpectedly, no selone or diselenide was obtained in the case of the reaction with 3‐aminobenzo[b]furan‐2‐carbonitrile ( 14 ). The only product isolated was the selenide 16 (Scheme 4), the structure of which has been established by X‐ray crystallography.