Reactions of 1,3-dioxacycloalkanes and their 2-arsena, 2-bora, 2-germa, 2-sila,and 2-thia analogs with nitriles

New reactions of five-, six-, and seven-membered 1,3-dioxacycloalkanes and their 2-arsena, 2-bora, 2-germa, 2-sila, and 2-thia analogs with nitriles giving rise to 1,3-oxazacycloalkanes and then to amino alcohols are surveyed. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1499–1507, July, 2005.     

Efficient,Iron-Catalyzed Synthesis of 2-Mercaptobenzothiazole Through S-Arylation/Heterocyclization of 2-Haloaniline with Potassium Xanthate

A mild and practical method for the synthesis of 2-mercaptobenzothiazole has been developed by using iron as an efficient catalyst. The present tandem reaction process allows access to a wide range of 2-mercaptobenzothiazoles in good to excellent yields by the reaction of 2-haloaniline with potassium O-ethyl dithiocarbonate in the presence of FeF₃ as a catalyst and 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl as a ligand under an atmosphere of argon.     

4-Formylazetidin-2-ones, synthon for the synthesis of (2R,3S) and (2S,3R)-3-amino-2-hydroxydecanoic acid (AHDA)

An efficient synthesis of 3-amino-2-hydroxydecanoic acid (AHDA), a nonproteinogenic amino acid, using enantiopure 3-benzyloxy-4-formylazetidin-2-one as a building block is described. Both the enantiomers of AHDA have been synthesized from the corresponding enantiomer of 3-benzyloxy-4-formylazetidin-2-one in good yield and optical purity.     

Design,Synthesis and Late-Stage Modification of Indane-Based Peptides via [2+2+2] Cyclotrimerization

Here, we prepared several dipeptides containing 2-aminoindane-2-carboxylic acid (Aic) and carried out further synthetic transformations. Synthesis and purification of modified peptides by using [2+2+2] cyclotrimerization is a challenging task. We are able to modify the unusual amino acids and peptide derivatives by late-stage incorporation of benzylhalo functionality. To incorporate benzylhalo moiety we used [2+2+2] cyclotrimerization in the presence of Mo(CO)₆. These halo derivatives are potential substrates for further modification by Sonogashira reaction, Suzuki–Miyaura cross-coupling, sultine formation, and the Diels–Alder reaction sequence.     

New synthesis of 2-nitroaryldifurylmethanes

A new approach has been developed for the synthesis of 2-nitroaryldifurylmethanes based on the condensation of derivatives of 2-nitrobenzaldehyde and 2-alkylfurans in methylene chloride in the presence of polyphosphoric acid (PPA) silyl ester. The use of such reaction conditions reduces resin formation, which enables the final products to be isolated in higher yields. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1796–1799, December, 2005.     

H_2O_2氧化N_2生成N_2O和H_2O机理的研究

采用量子化学计算方法研究了Ｈ２Ｏ２ 氧化Ｎ２ 生成Ｎ２Ｏ 和Ｈ２Ｏ 的机理．结果发现, Ｈ２Ｏ２ 氧化Ｎ２ 先通过１ 个四元环过渡态形成中间体Ｈ２Ｎ２Ｏ２ 分子,Ｈ２Ｎ２Ｏ２ 再通过一个五元环过渡态形成Ｎ２Ｏ和Ｈ２Ｏ．根据计算得到的每步反应的活化能,得知Ｈ２Ｏ２ 氧化Ｎ２ 生成中间体Ｈ２Ｎ２Ｏ２ 分子是整个反应的控制步骤．     

A facile synthesis of 4-aryl-2H-1-benzopyran-2-ones

Reaction of 2-hydroxybenzophenones (1,3,7,8) with ethoxycarbonyl-methylenetriphenylphosphorane affords 4-aryl-2H-1-benzopyran-2-ones (2,4–6) in excellent yields.

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Eine einfache Synthese für 4-Aryl-2H-1-benzopyran-2-one

Zusammenfassung Die Reaktion der 2-Hydroxybenzophenone1,3,7 und8 mit Ethoxycarbonyl-methylentriphenylphosphoran ergab die 4-Aryl-2H-1-benzopyran-2-one2 und4–6 in ausgezeichneten Ausbeuten.

     

Cu2+/TiO2对甲基橙的光催化降解机理

以自制的掺铜离子的混晶型二氧化钛为光催化剂,考察了甲基橙光催化降解过程中pH值和光源的影响,提出了两种不同的光催化降解机理:在高压汞灯照射下,TiO2的价带电子被激发到导带,光生电子和空穴主要通过Cu2+ 的短路循环而复合,光催化剂的活性降低;在太阳光照射下,甲基橙发生自身光敏化氧化反应,受激电子从单线态或三线态的甲基橙分子跃迁到TiO2的导带,Cu2+起到电荷传递中继站的作用,加速了注入电子向H2O2的转移,从而促进了甲基橙的光催化降解。     

CO2和N2电还原中缺陷及界面工程的最新进展

实现碳氮循环是人类社会发展的迫切要求,也是催化领域的热门研究课题。在可再生能源的推动下,电催化技术引起了人们的广泛关注,且可以通过改变反应电压获得不同的目标产品。基于此,电催化技术被认为是缓解当前能源危机和环境问题的有效策略,对实现碳中和具有重要意义。其中,电催化CO₂还原反应(CO₂RR)和N₂还原反应(N₂RR)是一种有前途的小分子转化策略。然而,CO₂和N₂均为线性分子,其中C＝O和N≡N键的高解离能导致了它们高的化学惰性。此外,最高占据分子轨道(HOMO)和最低未占分子轨道(LUMO)之间的巨大能量间隙使它们具有高的化学稳定性;且CO₂和N₂的低质子亲和力使它们难以被直接质子化。另一方面,由于CO₂RR和N₂RR与析氢反应(HER)具有相近的氧化还原电位,造成其与HER之间存在竞争性关系,这也是致使催化剂在CO₂RR和N₂RR转化效率低的重要影响因素。因此,CO₂RR和N₂RR仍然面临着过电位高及法拉第效率低等问题。为了克服这些瓶颈,人们为提升CO₂RR和N₂RR电催化剂性能做出了很多努力。众所周知,电催化过程发生在催化剂表面,主要涉及质量传递和电子转移等过程。由此可见,催化剂的性能与其质量和电子传输能力密切相关,而调控催化剂表面结构可以优化活性点的质量和电子转移行为。电催化剂的缺陷和界面工程可通过表面原子工程来实现电子结构调控,对于提高气体吸附能力、抑制HER、富集气体及稳定中间产物等具有重要意义。到目前为止,所报道的各种缺陷和复合电催化剂在提高CO₂RR和N₂RR催化性能等方面均表现出巨大的潜力。在此,我们综述了CO₂RR和N₂RR中催化剂缺陷工程及界面工程的最新进展;首先讨论了四种不同的缺陷(空位、高指数晶面、晶格应变和晶格无序)对CO₂RR和N₂RR性能的影响;然后,总结了界面工程在聚合物-无机复合材料催化剂中的重要作用,并给出了典型实例;最后,展望了原子级电催化剂工程的发展前景,提出了开发和设计高效CO₂RR和N₂RR电催化剂的未来发展方向。     

Concise syntheses of 2-aminoindans via indan-2-ol

2-Amino-5,6-dimethoxyindan hydrochloride was synthesized in seven steps and with an overall yield of 48%. Indan-2-ol was converted to 5,6-dibromo-indan-2-ol in three steps by acetylation, electrophilic bromination and deacetylation. Dimethoxylation of 5,6-dibromoindan-2-ol with NaOCH₃ in the presence of CuI gave 5,6-dimethoxy-indan-2-ol, which was converted to 2-amino-5,6-dimethoxyindan hydrochloride by azidation, followed by Pd-C catalyzed hydrogenation. Similarly, 2-amino-5-bromoindan was synthesized in five steps and with an overall yield of 50%. Indan-2-ol was converted to 2-aminoindan by azidation followed by Pd-C catalyzed hydrogenation. The reaction of 2-aminoindan with 2.5 equiv Br₂ afforded 2-amino-5,6-dibromoindan.     

Synthesis of 2-Arylimidazo[l, 2-a]pyrimidines in Ionic Liquids

Room temperature ionic liquids were used as a "green" recyclable alternative to conventional solvents in the synthesis of pharmaceutically useful compounds 2-arylimidazo[1, 2-a] pyrimidines through Tschotschibabin reaction of a-bromoacetophenones with 2-aminopyrimidine in good yields.     

Crystal Structure of (1R,4R;1S,4S)2-Amino-3-Cyano-1,4-Diphenyl-2-Cyclopentene-1-ol

1INTRODUCTIONIntheearly1970'sthreegroupsofinvestigatorsL,~,'foundthatlow-valenttita-nium,preparedbythereactionofstrongreducingagentswithtitaniumtrichlorideortitaniumtetrachlorideintetrahydrofuran,canabstractoxygenfromketonesoraldehydes,leadingtotheforma-tionofolefins.Theinterestinthereactioninducedbylow--valenttitaniumreagentsisincreasingandalargenumberoffunctionalgroupscanbereduceds4-6).Recent-ly,wefoundthatthetitlecompoundisObtainedbycy-cllzatlonreactionof(3--oxo-1,3-diphenyl)propyl-pro…     

Synthesis and unusual [2+2]-cycloaddition reactions of ethyl 4-chloro-2-oxobut-3-ynoate with unactivated alkenes

The highly activated acetylenes, ethyl 4-chloro-2-oxobut-3-ynoate and ethyl 4-bromo-2-oxobut-3-ynoate, were prepared from readily available bis(trimethylstannyl)acetylene in two steps with high overall yield. An unusual ability of the former to furnish [2+2]-cycloadducts with 1,1-disubstituted alkenes in the absence of irradiation and catalysts was discovered. The cycloaddition of ethyl 4-chloro-2-oxobut-3-ynoate to the 1,2-disubstituted alkenes was shown to be effectively catalyzed with stannic chloride.     

Catalytic enantioselective [2+2]-cycloaddition reaction of 2-methoxycarbonyl-2-cyclopenten-1-one by chiral copper catalyst

A new catalytic system for enantioselective [2+2]-cycloaddition reaction of 2-methoxycarbonyl-2-cyclopenten-1-one with thioacetylene derivatives is described. The use of a catalytic amount (20-30 mol%) of copper(II) salt with chiral bis-pyridine ligand was found to be effective in promoting the [2+2]-cycloaddition reaction, furnishing the corresponding bicyclic compound in good yield and good enantioselectivity.     

超细粉TiO2光催化氧化SO2的研究

Ti O2 作为性能优良的光催化氧化剂在有机污染物的光降解方面已得到了广泛重视 [1～ 3] .已经发现 ,Ti O2 超细粉末的晶型、表面积、表面修饰及基团密度等均影响其光催化活性 .本文通过 Ti O2 对SO2 的光催化氧化性能研究了 Ti O2 的光催化活性受表面态的影响 ,并给出了 SO2 的光催化氧化反应的机制及动力学关系 .1　实验部分1 .1　仪器与试剂　表面光电压谱仪 ( SPS,吉林大学研制 ) ;MK 型电子能谱仪 ;370 0型气相色谱仪 ;石英光化学反应瓶 (自制 ,30 0 m L) ;40 0 W高压汞灯 .采用 Sol- gel法制备 Ti O2 超细粉 [4 ] ,经 32 0 ,4…     

An efficient HCl promoted Petasis reaction of 2-pyridinecarbaldehydes,amines and 1,2-oxborol-2(5H)-ols

A Petasis reaction of 2-pyridinecarbaldehydes with various amines and 4-substituted 1,2-oxaborol-2(5H)-ols was developed. In the presence of HCl, the reaction proceeded smoothly under very mild conditions and the corresponding desired products were obtained in medium to excellent yields. This method allows the access a wide range of highly functionalized allylic alcohols, which might be useful compounds in medicinal and material chemistry.     

HYDROGENATION OF CO_2 OVER ULTRAFINECuO-ZnO-SiO_2 CATALYST-REACTION CONDITIONS AND MECHANISM

IntroductionAsoncofthemostabundantandcheapestcarbonsourccs,Co2u,ithsteadilyincreasingconcentrationintheatmospherenotonlyleadstothelossofcarbonsource,butalsocausesgrccnhouseeffects.Recently,Co2wastestedasafecdstockformcthanolproductionovcrdiffcrentcatalystsclse.'hcrell'21,butmostofthesecatalystswerebasedonthecombinationofcoppcrandzincandpreparedbycoprecipitation,ioncxchangcor'l3'4]Accordingtoextensivestudiesaboutsupports,SiO2wasoncoftheimpregnationl3'4]Accordingtoextensivestudiesaboutsupport…     

Novel synthesis of the 2-azaanthraquinone alkaloid, scorpinone, based on two microwave-assisted pericyclic reactions

The total synthesis of the 2-azaanthraquinone alkaloid, scorpinone (4), isolated from the mycelium of a Bispora-like tropical fungus, has been completed in nine steps. The two key steps involve a microwave-assisted thermal electrocyclic reaction for the synthesis of an 8-oxygenated isoquinoline skeleton from a 1-aza 6π-hexatriene system, and a regioselective microwave-assisted [4+2] cycloaddition for the construction of a 2-azaanthraquinone framework.     

Synthesis of substituted 1-(2-arylvinyl)-2-azolyl-1-pyridylethanols-1

A series of new 1-(2-arylvinyl)-2-azolyl-1-pyridylethanols-1 has been obtained with various positions of the nitrogen atom in the pyridine fragment and with substituents in the benzene ring, by the reaction of (2-arylvinyloxiran-2-yl)pyridines with triazole and imidazole, for agrochemical screening. The compounds mentioned displayed high fungicidal activity. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1167–1174, August, 2007.     

固体强酸催化剂S_2O_8~(2-)/ZrO_2-Al_2O_3-M_2O_3(M=Cr,Ce,La)的制备

固体强酸具有酸强度高 ,不腐蚀设备 ,不污染环境 ,与产物分离方便等特点 ,是一种对环境友好的催化剂。业已发现固体强酸对许多重要的有机反应如烃类异构化、傅克酰基化、傅克烷基化、酯化、缩合、聚合、氧化等具有良好的催化活性 ,可替代传统的浓 H2 SO4 及 Al Cl3、HF等高污染催化剂。在前文 [1]基础上 ,本文通过添加 Cr2 O3、Ce2 O3和 La2 O3对催化剂 S2 O2 - 8/Zr O2 - Al2 O3改进后制备出 S2 O2 - 8/Zr O2 -Al2 O3- M2 O3( M=Cr,Ce,La)系列固体强酸催化剂 ,用对乙酸和正丁醇的酯化转化率评价了催化活性 ,用 XRD、BET、流…