新型氮杂环卡宾-钌(II)催化剂的合成及催化活性

以1,3-双(2,6-二异丙基苯基)咪唑鎓盐酸盐（IPrHCl, 4a)或1,3-双［2,6-二（1-乙基丙基）苯基］咪唑鎓盐酸盐（IPent·HCl, 5a),及Grubbs 第一代催化剂和2-异丙氧基苯乙烯为原料,经去质子化反应和烯烃复分解反应合成了两种新型的NHC-钌催化剂4c和5c,其结构经¹H NMR, ¹³C NMR和HR-MS(ESI)表征。并研究了4c和5c的性能。结果表明：4c和5c的稳定性较好,对关环复分解反应有良好的催化活性。     

关环复分解反应(RCM)及其催化剂研究进展

综述了近年来关环复分解 (RCM )反应及其催化剂的研究进展 ,对RCM反应发展以来被广泛应用的催化剂 ,如Schrock催化剂和Grubbs催化剂等进行了归纳和总结 ,讨论了RCM反应在全合成中的应用     

贵金属钌基催化剂合成及应用研究进展

钌催化剂是近年来新兴的贵金属催化剂,其负载型催化剂具有节约成本、可回收利用、催化性能优异等优势,受到研究人员的广泛关注.本文对负载型钌基催化剂在氨合成反应、加氢反应、氧化反应的合成及应用进行了综述,主要阐述了反应过程中的载体与助剂、制备方法和催化性能,并对当前反应中存在的问题进行归纳和总结,最后提出负载型钌基催化剂现阶...     

烯合成反应简介

烯合成反应是有机化学中最简单,应用最广的反应之一,(?)常被许多教科书所忽略。本文拟对烯合成反应及其机理问题作简要的论述,并介绍它在有机合成中的一些应用。     

氨合成催化剂及其催化反应机理研究进展

本文综述了氨合成这一最重要的工业多相催化过程80 多年来的研究进展。介绍了氨合成熔铁催化剂、氨合成钌催化剂的发展以及对氨合成催化反应机理的不同看法。     

金属卡宾模板导向的多咪唑鎓盐大环合成

本文报道了一种共价有机大环化合物的高效合成方法。利用双咪唑鎓盐H₂-L1(BF₄)₂(L1=A1,B1)和氧化银反应,生成双核银卡宾大环化合物[Ag₂(L1)₂](BF₄)₂(L1=A1,B1),其中连接在2个卡宾配体上的端烯取代基分别排列在环的两侧。随后,通过金属卡宾模板导向的烯烃复分解反应进行关环,制备得到闭环的双核银卡宾大环化合物[Ag₂(L2)](BF₄)₂(L2=A2,B2)。最后,移除模板银离子即可得到拥有空腔结构的共价有机大环化合物H₄-L2(BF₄)₄(L2=A2,B2)。此类多咪唑鎓盐大环的尺寸和形状可以通过改变氮杂环卡宾前驱体连接单元的长度或者宽度进行精细调节。初步研究表明,该大环受体在碘离子的传感、检测和识别方面具有潜在的应用前景。     

i氨合成催化剂的研究进展*

高稳定性、高活性、低成本的氨合成催化剂的研究已成为新的研究热点。本文从载体的制备和改性方法、钌活性组分还原与负载、助剂的机理及其作用等方面简要地介绍了氧化物负载钌催化剂的最新研究进展,此外,结合密度泛函理论的计算和实验研究成果,介绍了合金型催化剂特别是熔铁型合金催化剂、氮化物金属合金体系及负载型多金属氨合成催化剂的研究现状,指出了氧化物负载钌催化剂及合金型催化剂研究存在的一些问题并展望了氨合成催化剂的发展前景。     

Synthesis of (6,6′)-C-Linked Pseudodisaccharides

A series of (6,6′)-C-linked pseudodisaccharides has been prepared using a general synthetic strategy of olefin metathesis in the presence of Grubbs second-generation catalyst. Yields were excellent in every case.     

Total Synthesis of (+)‐Cryptocaryalactone and of a Diastereoisomer of (+)‐Strictifolione via Ring‐Closing Metathesis (RCM) and Olefin Cross‐Metathesis (CM)

Ring‐closing metathesis (RCM) and olefin cross‐metathesis (CM) reactions were used as the key steps for the synthesis of (+)‐cryptocaryalactone ( 1 ) and the first synthesis of the diastereoisomer 3 of (+)‐strictifolione, starting from the commercially available L ‐malic acid (=(2S)‐2‐hydroxybutanedioic acid).     

Catalytic Performance of Ruthenium‐Supported Ionic‐Liquid Catalysts in Sustainable Synthesis of Macrocyclic Lactones

Thirteen‐ to eighteen‐membered lactones were synthesized by ring‐closing olefin‐metathesis reactions of bis‐olefins with heterogeneous Grubbs‐supported ionic‐liquid catalysts (SILCs), in which homogeneous Grubbs catalysts were confined in pores of alumina with the aid of an ionic liquid. The Grubbs‐SILCs exhibited higher catalytic performance than their homogeneous counterparts and could be repeatedly recovered by simple filtration and re‐used several times.     

Highly chemo- and stereoselective intermolecular coupling of diazoacetates to give cis-olefins by using Grubbs second-generation catalyst

Highly stereoselective formation of cis-2-ene-1,4-diesters by homo- and heterocoupling of alpha-diazoacetates in the presence of Grubbs second-generation catalyst is demonstrated. The dual reactivity of the catalyst in alkene metathesis and diazocoupling has been exploited in the synthesis of 12-26-membered macrocyclic dienyl dilactones by one-pot carbene dimerisation/ring-closing metathesis.     

Immobilization of the Grubbs second-generation ruthenium-carbene complex on poly(ethylene glycol): a highly reactive and recyclable catalyst for ring-closing and cross-metathesis

A poly(ethylene glycol)-bound Hoveyda-Grubbs Ru catalyst derived from the Grubbs second-generation Ru carbene complex was synthesized and shown to be highly reactive in the ring-closing metathesis of a wide variety of diene substrates, yielding di-, tri-, and tetra-substituted carbocyclic and heterocyclic olefins. The immobilized catalyst also proved to be highly reactive and recyclable in cross-metathesis and ring-opening/cross-metathesis. In all cases tested, the catalyst exhibited a high level of recyclability and reusability.     

Substantiating the influence of pore surface functionalities on the stability of Grubbs catalyst in mesoporous SBA-15 silica

The influence of pore surface functionalities in mesoporous SBA-15 silica on the stability of a model olefin metathesis catalyst, namely Grubbs I, is substantiated. In particular, it is demonstrated that the nature of the interaction between the ruthenium complex and the surface is strongly depending on the presence of surface silanols. For this study, differently functionalized mesoporous SBA-15 silica materials were synthesized according to standard procedures and, subsequently, the Grubbs I catalyst was incorporated into these different host materials. All of the materials were thoroughly characterized by elemental analyses, nitrogen physisorption at -196 °C, thermogravimetric analyses, solid-state NMR spectroscopy, and infrared spectroscopy (ATR-IR). By such in-depth characterization of the materials, it became possible to achieve models for the surface/catalyst interactions as a function of surface functionalities in SBA-15; for example, in the case of purely siliceous silanol-rich SBA-15, octenyl-silane modified SBA-15, and silylated equivalents. It was evidenced that large portions of the chemisorbed species that are detected spectroscopically arise from interactions between the tricyclohexylphosphine and the surface silanols. A catalytic study using diethyldiallylmalonate in presence of the various functionalized silicas shows that the presence of surface silanols significantly decreases the longevity of the ring-closing metathesis catalyst, whereas the passivation of the surface by trimethylsilyl groups slows down the catalysis rate, but does not affect significantly the lifetime of the catalyst. This contribution thus provides new insights into the functionalization of SBA-15 materials and the role of surface interactions for the grafting of organometallic complexes.     

Grubbs catalyst-mediated cycloisomerization of allenenes

The novel ruthenium benzylidene catalyst-mediated cycloisomerization of allenenes, having an alkyl appendage at the allenic terminus, resulting in the construction of cyclohexene, tetrahydropyran, and tetrahydropyridine skeletons was developed.     

The Olefin Reaction between Crude Palm Oil Fatty Acid Methyl Ester (CPO FAME) and Ethylene Using Grubbs II Catalyst

Renewable materials derived from vegetable oils are now widely developed for obtaining green polymers. One of the applications of those polymers is in the field of Enhanced Oil Recovery (EOR) where the polymers are put in the injection wells to increase water viscosity resulting in higher efficiency of oil production. Indonesia is very rich in crude palm oil and therefore, it was chosen as the starting material for polymer synthesis. The objective of this work is to prepare the monomer first, by doing the olefin metathesis reaction between crude palm oil FAME (fatty acid methyl ester) and ethylene. The reaction was carried out using a Grubbs II catalyst in order to obtain methyl 9-decenoate which is used later as the monomer for EOR application. The resulting product was characterized using Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared (FTIR) spectroscopy as well as Gas Chromatography Mass Spectrometry (GC-MS). Based on the functional group analysis, it was found that methyl 9-decenoate has successfully been synthesized.     

Grubbs Metathesis Enabled by a Light-Driven gem-Hydrogenation of Internal Alkynes

[(NHC)(cymene)RuCl₂] (NHC=N-heterocyclic carbene) complexes instigate a light-driven gem-hydrogenation of internal alkynes with concomitant formation of discrete Grubbs-type ruthenium carbene species. This unorthodox reactivity mode is harnessed in the form of a “hydrogenative metathesis” reaction, which converts an enyne substrate into a cyclic alkene. The intervention of ruthenium carbenes formed in the actual gem-hydrogenation step was proven by the isolation and crystallographic characterization of a rather unusual representative of this series carrying an unconfined alkyl group on a disubstituted carbene center.     

Synthesis of 1,3-cyclohexadienes by tandem diene-alkyne metathesis: improved procedure

A practical synthesis of 2-substituted 1,3-cyclohexadienes by the cross enyne metathesis between alkynes and 1,5-hexadiene is reported. The isolation of the 1,3-cyclohexadienes has been hampered by the formation of an inseparable triene by-product. The use of a second consecutive cross alkene metathesis to give water-soluble products allowed removal of this by-product. Using this one-pot procedure, a synthesis of cyclohexadienes from simple starting materials was developed. The procedure was used in a three-step synthesis of a functionalized tetrahydroquinoline using Pd(II)-catalyzed chloroacetoxylation (Bäckvall reaction) for cyclohexadiene functionalization.