Copper catalyzed/mediated synthetic methodology for ebselen and related isoselenazolones

Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.     

2-噻吩基苯酚的合成优化

以廉价的2-溴苯甲醚制取了格氏试剂,通过Kumada偶联反应得到2-噻吩基苯甲醚,再通过吡啶盐酸盐脱甲基得到2-噻吩基苯酚。从催化剂、配体、溶剂等方面对Kumada偶联反应进行了筛选和优化,结果表明Kumada偶联反应时,72℃以Pd（dppf）Cl2（0.001 mol）为催化剂（dppf,二茂铁）,三苯基膦（PPh3）和1,1’-双（二苯基膦）二茂铁（dppf）作为配体,四氢呋喃和乙二醇二甲醚为混合溶剂,反应16 h,得到2-噻吩基苯甲醚,纯度95%,产率65%。再通过吡啶盐酸盐脱甲基得到2-噻吩基苯酚,纯度大于98%,产率65%。该方法原料便宜,后处理简单,收率较高。     

Reactions of diheteroaryl sulfoxides with heteroaryllithiums—ligand coupling and exchange reactions

The reactions of heteroaryl sulfoxides with heteroaryllithiums gave various biheteroaryls and diheteroaryl sulfoxides as ligand coupling and ligand exchange products through sulfurane intermediates. Especially, the reaction of di-2-furyl sulfoxide with 2-pyridyllithium proceeded first by a ligand exchange reaction to form 2-furyllithium and 2-furyl 2-pyridyl sulfoxide, which then underwent ligand coupling with 2-pyridyllithium to afford 2,2′-bipyridyl. Furthermore, it was found that the occurrence of the ligand coupling reaction depends on the stereoisomerism of the sulfurane intermediate formed. © 1996 John Wiley & Sons, Inc.     

钯催化下三正丁基杂环基锡和酰氯及取代芳烃偶联反应的研究

本文研究了在Pd(PPh3)2Cl2(1)催化下的三正丁基-2-呋喃基锡(6a), 三正丁基-2-噻吩基锡(6a), 三正丁基-2-(N-甲基)吡咯基锡(6c)和菊酰氯(5), 肉桂酰氯(7)的交联反应。发现除了三正丁基-2-(N-甲基)吡咯与5的不寻常反应得到2, 5-二取代的吡咯衍生物外, 其余反应皆以70～87%的产率得到交叉偶联产物。本文同时还报道了钯催化下有机锡试剂与取代卤代芳烃反应, 高收率地得到了不对称的杂环基芳烃和双杂环化合物。在合成的交联产物中, 化合物2, 8, 9, 15, 16与17均为新化合物。     

偶合反应化学发光酶免疫分析研究: I. HRP及其标记物的化学发 光测定

本文将辣根过氧化物酶(HRP)催化过氧化氢氧化KI生成I~2的反应与Luminol-I~2的化学发光反应相偶合,提出了测定HRP及其抗原、抗体标记物的高灵敏度的化学发光法。检测下限为7pg,线性范围为10-6000pg。通常使用的HRP直接催化Luminol-H~2O~2化学发光法灵敏度高10-100倍;克服了固相吸附法直接测定HRP标记物的缺陷,提高了测定的选择性。文中还对该偶合反应的机理及其动力学特性进行了研究。     

Heterogeneously catalyzed aerobic oxidative biaryl coupling of 2-naphthols and substituted phenols in water

The oxidative coupling reaction can efficiently be promoted by supported ruthenium catalyst Ru(OH)x/Al2O3. A variety of 2-naphthols and substituted phenols can be converted to the corresponding biaryl compounds in moderate to excellent yields using molecular oxygen as a sole oxidant in water without any additives. The catalysis is truly heterogeneous in nature, and Ru(OH)x/Al2O3 can easily be recovered after the reaction. The catalyst can be recycled seven times with the maintenance of the catalytic performance, and the total turnover number reaches up to 160. The results of competitive coupling reactions suggest that the present oxidative biaryl coupling reaction proceeds via the homolytic coupling of two radical species and the Ru(OH)x/Al2O3 catalyst acts as an one-electron oxidant. Two radical species are coupled to give the corresponding biaryl product, and the one-electron reduced catalyst is reoxidized by molecular oxygen. The amounts of O(2) uptake and H(2)O formation were almost one-quarter and one-half the amount of substrate consumed, respectively, supporting the reaction mechanism. The kinetic data and kinetic isotope effect show that the reoxidation of the reduced catalyst is the rate-limiting step for the coupling reaction.     

Theoretical and Experimental Study on Reaction Coupling： Dehydrogenation of Ethylbenzene in the Presence of Carbon Dioxide

Dehydrogenation of ethylbenzene (EB) to styrene (ST) in the presence of CO2, in which EB dehydrogenation is coupled with the reverse water-gas shift (RWGS), was investigated extensively through both theoretical analysis and experimental characterization. The reaction coupling proved to be superior to the single dehydrogenation in several respects. Thermodynamic analysis suggests that equilibrium conversion of EB can be improved greatly by reaction coupling due to the simultaneous elimination of the hydrogen produced from dehydrogenation. Catalytic tests proved that iron and vanadium supported on activated carbon or Al2O3 with certain promoters are potential catalysts for this coupling process. The catalysts of iron and vanadium are different in the reaction mechanism, although ST yield is always associated with CO2 conversion over various catalysts. The two-step pathway plays an important role in the coupling process over Fe/Al2O3, while the one-step pathway dominates the reaction over V/Al2O3. Coke deposition and deep reduction of active components are the major causes of catalyst deactivation. CO2 can alleviate the catalyst deactivation effectively through preserving the active species at high valence in the coupling process, though it can not suppress the coke deposition.     

溴化锌-季(鎓)三溴盐催化二氧化碳和环氧化合物偶联反应

研究了溴化锌-季鎓三溴盐催化二氧化碳和环氧化合物偶联反应,考察了反应温度、压力和不同金属盐对反应的影响以及催化剂的循环使用性能.结果表明,在413 K和1.0 MPa条件下,以溴化锌为催化剂,苯基三甲基三溴化铵为共催化剂,无需加入任何溶剂就可以使二氧化碳和环氧化合物发生偶联反应,并以很高的收率得到环碳酸酯.     

Total synthesis of the alkaloids martinelline and martinellic acid via a hetero Diels-Alder multicomponent coupling reaction

[reaction: see text] A concise synthesis of the guanidine alkaloids, (+/-)-martinelline and (+/-)-martinellic acid, using a protic acid catalyzed 2:1 hetero Diels-Alder coupling reaction between N-Cbz 2-pyrroline and methyl 4-aminobenzoate, is described. Protic acid catalysis, rather than Lewis acid catalysis, was necessary to achieve the desired sense of diastereocontrol in the coupling reaction.     

Straightforward access to 2-iminoisoindolines via three-component coupling of arynes, isocyanides and imines

A three-component coupling reaction of arynes, isocyanides and N-tosylaldimines has been developed to offer modest to high yields of diverse 2-iminoisoindolines in one step. Intermediacy of arynes in the coupling has been verified by the reaction of unsymmetrical arynes.     

Catalytic Systems Containing p-Toluenesulfonic Acid for the Coupling Reaction of Formaldehyde and Methyl Formate

The coupling reaction of formaldehyde(FA)and methyl formate(MF)to form methyl glycolate(MG)and methyl methoxy acetate(MMAc),catalyzed by p-toluenesulfonic acid(p-TsOH)as well as assisted by different kinds of solvents or Ni-containing compounds,had been investigated.The results showed that when the reaction was carried out at 140℃,with a molar ratio of FA to MF of 0.65:1, molar fraction of p-TsOH to total feedstock of 11.0%,and reaction time of 3 h,the yield of MG and MMAc was 31.1% and 17.1%,respectively,p-TsOH catalyzed the coupling reaction by means of the synergistic catalysis of protonic acidity and soft basicity.Adding extra solvents to the reaction system was unfavorable for the reaction.The composite catalytic system consisting of p-TsOH and NiX_2(X=Cl,Br,I)exhibited a high catalytic performance for the coupling reaction,and NiX_2 acted as a promoter in the reaction,whose promotion for the catalysis increased in the following order:NiCl_2相似文献   

Total synthesis of leustroducsin B

Leustroducsin B was synthesized via a convergent route based on division of the leustroducsin molecule into three segments A, B, and C. Two coupling reactions (Julia coupling reaction and Nozaki-Hiyama-Kishi (NHK) reaction) were employed for coupling of segments A and B: segment A1 for the Julia coupling reaction was prepared by a combination of Sharpless asymmetric epoxidation and an epoxide-cleavage reaction with an organoaluminum reagent, while segment A2 for the NHK reaction was synthesized from optically active alcohol that had previously been prepared by lipase-catalyzed kinetic resolution. Segment B, whose structure was modified with some functional groups, was synthesized from (R)-malic acid by a combination of Wittig reaction and Sharpless asymmetric dihydroxylation, and segment C, containing a cyclohexane moiety, was prepared by asymmetric Diels-Alder reaction. Segment B was first coupled with segment A1 via the Julia coupling reaction, but the yield was low due to unexpected epimerization. The NHK reaction of segment A2 proceeded to give the coupling product in good yield. This product was coupled with segment C via Wittig and Stille coupling reactions, and finally, phosphorylation was carried out by partial hydrolysis of a cyclic phosphate to give leustroducsin B.     

低价钛诱导的芳香邻二酮及α-羟基酮的还原偶联反应

Treatment of aromatic 1 , 2-diketones or aromatic a-hydroxy ketones with an activated low-valent titanium reagent, prepared by reduction of TiCl3·1/3AlCl3 with a Zn-Cu reagent, gave an intermolecular coupling reaction leading to the (Z)-1, 2.3.4-tetraaryl-2-butenes. Apossible coupling reaction process was proposed for the aromatic a-hydroxy ketones.     

Efficient synthesis and properties of novel near-infrared electrochromic anthraquinone imides

An efficient synthesis of novel near-infrared electrochromic 6-substituted (NO2, Br) anthraquinone imides, i.e., 2a and 2b, was established. Bearing functional groups suitable for further structural modifications by nucleophilic substitution reaction and various metal-catalyzed coupling reactions (e.g., Suzuki coupling), 2a and 2b were easily transferred to 1a by reaction with 4-methoxyphenol and 1b by reaction with 4-hexyloxyphenylboronic acid, respectively. These new imides are electrochromic and absorb intensely in the near-infrared range of 700-1600 nm upon electrochemical reduction.     

金属醋酸盐催化合成聚丁二酸乙二醇酯预聚体和碳酸二甲酯

研究了醋酸盐催化碳酸乙烯酯（EC）和丁二酸二甲酯（DS）同时合成聚丁二酸乙二醇酯 (PES) 预聚体和碳酸二甲酯(DMC)的耦合反应新工艺。 采用气相色谱-质谱联用定性分析馏分组成;红外光谱、核磁共振表征了预聚物的结构;采用乌式粘度计测试了预聚物的特性粘数;气相色谱定量测定馏分碳酸二甲酯的收率以考察耦合反应的进度。 以对该反应催化效果最佳的无水醋酸锂为催化剂考察了物料配比、反应温度、反应时间、催化剂用量对耦合反应的影响,结果表明,最佳的工艺条件为：反应温度195～200 ℃,n(EC)∶n(DS)=2∶1,n(cat)∶n(EC+DS)=0.02∶1,反应时间为2 h,耦合反应所得的DMC收率为48.0%,聚丁二酸乙二醇酯预聚物的特性粘数为0.3787。     

Highly regio- and stereoselective halohydroxylation reaction of 1,2-allenyl phenyl sulfoxides. Reaction scope,mechanism, and the corresponding pd- or ni-catalyzed selective coupling reactions

A highly regio- and stereoselective halohydroxylation of 1,2-allenyl sulfoxides with X(+) and water was developed. The reaction shows E-stereoselectivity. In the iodohydroxylation reaction, I(2) was used to introduce the iodine atom. For bromohalohydroxylation, CuBr(2), NBS, or Br(2) can be used. When using I(2), NBS, or Br(2), the addition of LiOAc.2H(2)O is necessary for high yields of the halohydroxylation products. The chlorohydroxylation reaction was preformed by milling 1,2-allenyl sulfoxides and CuCl(2).2H(2)O with silica gel. Under the catalysis of a Pd(0) complex, the halohydroxylation products, that is, E-2-halo-1-phenylsulfinyl-1-alken-3-ols, can undergo Sonogashira, Suzuki, and Negishi cross-coupling reactions leading to Z-2-substituted-1-phenylsulfonyl-1-alken-3-ols. The C-S bond of the coupling product may undergo a further coupling reaction with organozincs under the catalysis of an Ni catalyst. Here, the presence of a hydroxyl group is important for a smooth coupling involving the C-S bond. Thus, optically active stereodefined multisubstituted allylic alcohols can be prepared by the reaction of the easily available optically active propargylic alcohols with sulfinyl chloride followed by E-halohydroxylation and a selective Pd- or Ni-coupling reaction.     

Simple and efficient nickel-catalyzed cross-coupling reaction of alkynylalanes with benzylic and aryl bromides

Highly efficient and simple coupling reactions of benzylic and aryl bromides with aluminium acetylide catalyzed by NiCl(2)(PPh(3))(2) are reported. The coupling reactions proceed at room temperature employing 4 mol% catalyst, affording coupling products in excellent yields of up to 95% in short reaction times. The system worked efficiently with aryl and heterocyclic bromides as well.     

Coriolis coupling and nonadiabaticity in chemical reaction dynamics

The nonadiabatic quantum dynamics and Coriolis coupling effect in chemical reaction have been reviewed, with emphasis on recent progress in using the time-dependent wave packet approach to study the Coriolis coupling and nonadiabatic effects, which was done by K. L. Han and his group. Several typical chemical reactions, for example, H+D(2), F+H(2)/D(2)/HD, D(+)+H(2), O+H(2), and He+H(2)(+), have been discussed. One can find that there is a significant role of Coriolis coupling in reaction dynamics for the ion-molecule collisions of D(+)+H(2), Ne+H(2)(+), and He+H(2)(+) in both adiabatic and nonadiabatic context.     

Acrylate formation via metal-assisted C-C coupling between CO2 and C2H4: reaction mechanism as revealed from density functional calculations

The reaction path for the formation of a binuclear hydrido-acrylate complex in a CO(2)-C(2)H(4) coupling process is explored in detail by locating the key intermediates and transition states on model potential energy surfaces derived from density functional calculations on realistic models. The formation of the new C-C bond is shown to take place via oxidative coupling of coordinated CO(2) and C(2)H(4) ligands resulting in a metalla-lactone intermediate, which can rearrange to an agostic species allowing for a beta-hydrogen shift process. The overall reaction is predicted to be clearly exothermic with all intermediates lying below the reactants in energy, and the highest barrier steps correspond to C-C coupling and beta-hydrogen transfer. The phosphine ligands are found to play an important role in various phases of the reaction as their dissociation controls the coordination of CO(2), the formation of the agostic intermediate, and the dimerization process; furthermore, their presence facilitates the oxidative coupling by supplying electrons to the metal center. Our results provide a theoretical support for the reaction mechanism proposed from experimental observations. The effect of the solvent medium on the relative energy of reaction intermediates and transition states is examined and found important in order to predict reliable energetics.     

The adsorption and reaction of a titanate coupling reagent on the surfaces of different nanoparticles in supercritical CO2

The adsorption and reaction in supercritical CO2 of the titanate coupling reagent NDZ-201 on the surfaces of seven metal oxide particles, SiO2, Al2O3, ZrO2, TiO2 (anatase), TiO2 (rutile), Fe2O3, and Fe3O4, was investigated. FTIR and TG analysis indicated that the adsorption and reaction were different on different particle surfaces. On SiO2 and Al2O3 particles, there was a chemical reaction of the titanate coupling reagent on the surfaces. On the surfaces of ZrO2 and TiO2 (anatase) particles, there were two kinds of adsorption, weak and strong adsorption. On the surfaces of TiO2 (rutile), Fe2O3, and Fe3O4 particles, there was only weak adsorption. The acidity or basicity of the OH groups on the particle surface was the key factor that determined if a surface reaction occurred. When the OH groups were acidic, the titanate coupling reagent reacted with these, but otherwise, there was no reaction. The surface density of OH groups on the original particles and the amount of titanate coupling reagent adsorbed and reacted were estimated from TG analysis. The reactivity of the surface OH groups of Al2O3 particles was higher than that of the SiO2 particles.