碱性离子液体[bmim]OH在Knoevenagel反应和Perkin反应中的应用

以碱性离子液体[bmim]OH作为催化剂, 在无溶剂条件下, 催化Knoevenagel反应和Perkin反应两类缩合反应. 实验结果表明, 该离子液体对Knoevenagel反应具有很高的催化活性, 一系列的芳香醛和活泼亚甲基化合物在室温条件下10～30 min内顺利完成反应, 以85%～95%的高产率生成取代烯烃产物. 离子液体经简单处理后能多次循环使用. 此外, 初步探讨了该碱性离子液体在Perkin反应中的应用.     

Efficient, green and regioselective synthesis of 1,4,5-trisubstituted-1,2,3-triazoles in ionic liquid [bmim]BF4 and in task-specific basic ionic liquid [bmim]OH

Convenient and environmentally benign procedures have been reported for the synthesis of 1,4,5-trisubstituted-1,2,3-triazoles by the reaction of aryl azides with active methylene compounds in ionic liquid [bmim]BF₄ in the presence of l-proline as a catalyst and also in task-specific basic ionic liquid [bmim]OH. The methodologies defined herein avoid the severe conditions as posed by earlier existing methods and proved to be efficient in terms of good yields, operational simplicity, easy workup and short reaction time.     

Masked mercapto acid-driven MCR in task-specific ionic liquid: a new sterocontrolled entry into bicyclic 1,3-thiazines

An unprecedented multi-component reaction for the synthesis of thiosugar-annulated 1,3-thiazines is reported. The envisaged synthetic strategy involves the reaction of d-glucose/d-xylose and 2-methyl-2-phenyl-1,3-oxathiolan-5-one with AcONH₄/RNH₂ in task specific ionic liquid (TSIL), [bmim]SCN which afforded thiosugar annulated 1,3-thiazines in excellent yields (83–93%). The reaction is effected via ionic liquid promoted Michael addition followed by mercaptoacetylative ring transformation in a one-pot procedure and the ionic liquid, [bmim]OH could be easily recycled for further use without any loss of efficiency and be used for the synthesis of [bmim]SCN, thus allowing recycling of the TSIL for further use.     

Recyclable zinc (II) ionic liquid catalyzed synthesis of azides by direct azidation of alcohols using trimethylsilylazide at room temperature

A new efficient method has been reported for the synthesis of azides by direct azidation of alcohols with TMSN₃ in presence of recyclable task specific ionic liquid (TSIL) [bmim]ZnCl₃ as a catalyst in DCM at room temperature. Ionic liquid [bmim]ZnCl₃ was synthesized under solvent free conditions and characterized by IR, ¹H NMR, ¹³C NMR and HRMS. The Lewis acidity of catalyst was also examined using IR spectroscopy. The main features of this new methodology are high yields of products, recyclability of catalyst, scalability of reaction to gram scale and short reaction time.     

离子液体中β-葡萄糖苷酶生物催化合成红景天甙

比较了聚乙二醇修饰的β-葡萄糖苷酶在三种离子液体([bmim]PF6,[bmim]BF4,[bmim]Tf2N)及两种常用有机溶剂(1,4-二氧六环、正己烷)中的催化性能,确定了适宜的反应介质;考察了底物浓度、温度、体系含水量和反应时间等因素对β-葡萄糖苷酶催化合成红景天甙反应的影响.结果表明,在最佳反应介质[bmim...     

[bmim]OH-promoted one-pot,three-component synthesis of β-nitro sulfides in water

A task-specific ionic liquid, [bmim]OH, has been found to be a highly efficient catalyst for one-pot, three-component coupling of aryl aldehydes, nitromethane, and thiols for the synthesis of β-nitro sulfides in water. The main advantages of the present protocol include the use of inexpensive simple substrates and an ionic liquid as a basic catalyst.     

Basic Ionic Liquid Promoted Domino Knoevenagel–Thia‐Michael Reaction: An Efficient and Multicomponent Strategy for Synthesis of 1,3‐Thiazines

An efficient, three‐component strategy for synthesis of 1,3‐thiazines with high atom economy in one‐pot mediated by room temperature basic ionic liquid is described here. The strategy involves basic ionic liquid, [bmim]OH‐catalyzed Knoevenagel condensation between ethyl cyanoacetate and aromatic aldehyde and subsequent thia‐Michael addition with substituted thioureas. The reaction sequence is smooth and quantitative under ambient temperature. [bmim]OH was recovered and reused four times without any appreciable decrease in its reactivity and product yield.     

Ionic Liquid Promoted Multicomponent Reaction: A Good Strategy for the Eco‐Compatible Synthesis of Functionalized Pyrroles

Task specific [bmim]BF₄ was found to be reusable, alternative, and effective reaction media for multicomponent synthesis of highly functionalized pyrroles. Generality of the procedure was established by synthesizing various pyrroles from wide range of aromatic/aliphatic amine, phenacyl bromide, and electrophilic alkynes by utilizing this protocol without any acid or metal catalyst. Ecocompatibility, short reaction time, excellent yield, recyclability of [bmim]BF₄, low cost, easy work‐up, and mild reaction conditions are additional advantages of the procedure in the context of sustainable and green chemistry.     

An efficient conjugate hydrothiocyanation of chalcones with a task-specific ionic liquid

A new and efficient method of conjugate hydrothiocyanation of chalcones along with the preparation of a probe for demonstrating the utility of the resulting β-thiocyanato ketones in heterocyclic synthesis is reported. Chalcones undergo an efficient conjugate hydrothiocyanation with the task-specific ionic liquid (TSIL), 1-n-butyl-3-methylimidazolium thiocyanate ([bmim]SCN) followed by reaction with AcONH₄ or an amine to afford chemically and pharmaceutically interesting 2-amino-1,3-thiazines at room temperature in a one-pot procedure. After isolation of the product, the ionic liquid [bmim]OH could be used for the synthesis of [bmim]SCN, thus allowing recycling of the TSIL for further use.     

Hydrotalcite catalysis in ionic liquid medium: a recyclable reaction system for heterogeneous Knoevenagel and nitroaldol condensation

Knoevenagel condensation proceeds efficiently in recyclable [bmim]PF₆ and [bmim]BF₄ without any catalyst, and hydrotalcites in ionic liquid serve as a safe and recyclable reaction system for both Knoevenagel as well as nitroaldol condensations.     

碱性离子液体催化“一锅法”合成1,4-二氢吡喃并[2,3-c]吡唑

在碱性离子液体氢氧化1-丁基-3-甲基咪唑([bmim]OH)催化作用下,由芳香醛、丙二腈、苯甲酰乙酸乙酯和肼或苯肼"一锅法"合成了一系列1,4-二氢吡喃并[2,3-c]吡唑化合物.实验中考察了催化剂、反应温度、催化剂用量、溶剂对反应的影响,确定了最优反应条件,给出了可能的反应机理.此外催化剂可以方便地收回,且循环使用四次其催化活性并没有显著降低.目标产物经过了1H NMR,IR,MS和元素分析确证.合成方法条件温和、反应时间短、产率高且对环境友好.     

Efficient and Green Approaches for the Synthesis of 4H-Benzo[g]chromenes in Water,Under Neat Conditions,and Using Task-Specific Ionic Liquid

Facile and convenient procedures have been described for the synthesis of 4H-benzo[g]chromenes by one-pot condensation of aromatic aldehydes, malononitrile/ethyl cyanoacetate, and 2-hydroxy-1,4-naphthoquinone. The reaction has been accomplished using catalytic cetyltrimethylammonium bromide (CTAB) in water under reflux or under neat conditions at 110 °C. A task-specific ionic liquid, 1-butyl-3-methyl imidazolium hydroxide ([bmim]OH), has also been found to be an effective catalyst for this transformation. The protocols prove to be environmentally benign and offer advantages of good yields, short reaction times, and simple workup procedures. The ionic liquid could be recycled and reused for up to four runs without appreciable loss in the activity.     

Room Temperature Ionic Liquid： a Powerful Additive of Mn（Salen） Catalyzed Oxidation of sec-Alcohols

A simple, mild, efficient Mn(salen)-catalyzed oxidation system of secondary alcohols, in which the ionic liquid [bmim]PF6 acts as a powerful additive, has been described. The reaction proceeded with higher efficiency. The catalyst was more easier to recycle in ionic liquid [bmim]PF6 with a well-proportioned CH2Cl2 than in the single CH2Cl2 or ionic liquid.     

Ru-[bmim]BF4 的制备及催化苯选择加氢反应性能

以离子液体1-丁基-3-甲基咪唑四氟硼酸盐([bmim]BF4)-水混合溶剂为介质,采用化学还原法制备了Ru-[bmim]BF4催化剂,并利用紫外-可见光谱、红外光谱、透射电镜、X射线衍射和X射线光电子能谱对催化剂进行了表征.结果表明,Ru在[bmim]BF4中分散较好,粒径~2nm,且离子液体中咪唑阳离子与部分Ru形成了金属卡宾配合物.利用苯选择加氢反应对该催化剂性能进行了评价,发现Ru-卡宾配合物存在时,催化剂活性较低,但环己烯选择性较高.在本文反应条件下,苯转化率为12.2%,环己烯选择性为40.5%.重复使用该催化剂时,由于Ru-卡宾配合物在反应中转变为Ru0,其催化活性增加,但环己烯选择性下降.继续多次使用该催化剂,其性能基本保持稳定.     

The first ionic liquid-promoted three-component coupling strategy for an expeditious synthesis of β-nitrocarbonitriles/thiocyanates

A novel and convenient three-component coupling reaction of nitromethane, aromatic aldehydes and trimethylsilyl cyanide (TMSCN) or ammonium thiocyanate has been developed for an expeditious synthesis of β-nitrocarbonitriles or β-nitrothiocyanates, respectively, via C-C and C-S bond-forming reactions. The synthetic protocol strategically involves a one-pot sequential Henry reaction and a Michael addition efficiently promoted by the same ionic liquid [bmim]OH. The main advantages of the present approach include the use of inexpensive simple substrates and an ionic liquid as an efficient reaction promoter for the mild synthesis in a one-pot procedure.     

A Green and Novel Method of Synthesizing 2,2'-Arylmethylene Bis(3-hydroxy-5,5-dimethylcyclohex-2-enone) Catalyzed by L-Histidine in Ionic Liquid

An efficient and green approach to the synthesis of 2,2′‐arylmethylene bis(3‐hydroxy‐5,5‐dimethylcyclohex‐2‐enone) using L‐histidine as the catalyst is described. In addition, room temperature ionic liquid 1‐butyl‐3‐methylimidazonium tetrafluoroborate [bmim]BF₄ was used as green recyclable alternatives to volatile organic solvents for this condensation reaction. This green catalytic system can be recycled several times with no decreases in yields and reaction rates.     

咪唑阴离子型碱性离子液体的合成及其催化Knoevenagel缩合反应

设计合成了由1-丁基-3-甲基咪唑阳离子与咪唑阴离子搭配的[bmim]Im新型碱性离子液体并对其碱性进行研究.[bmim]Im离子液体的碱性与[bmim]OH的碱性接近且强于[bmim]OAc.在水溶液及室温条件下,2%的[bmim]Im离子液体对系列芳香醛与活泼的亚甲基化合物之间的Knoevenagel缩合反应具有较好的催化性能,目标产物的收率达到86%～95%,选择性为100%.同时,该催化剂体系具有良好的循环性能.     

1‐Butyl‐3‐methylimidazolium Hydrogen Sulfate [Bmim]HSO4: An Efficient Reusable Acidic Ionic Liquid for the Synthesis of 1,8‐Dioxo‐Octahydroxanthenes

1‐Butyl‐3‐methylimidazolium hydrogen sulfate [bmim]HSO₄ as an acidic ionic liquid was prepared and used as a catalyst for the synthesis of 1,8‐dioxo‐octahydroxanthenes in excellent yields and short reaction times at 80 °C. The ionic liquid was easily separated from the reaction mixture by water extraction and was recycled four times without any loss in activity.     

A Novel Green Preparation of a, a''''-Bis (substituted benzylidene)-cycloalkanones Promoted by FeCl_3 6H-2O in Ionic Liquid

a, a'-Bis(substituted benzylidene)cycloalkanones were efficiently prepared from cycloalkanones and benzaldehydes in [bmim][BF4] by using iron(III) chloride hexahydrate as a catalyst. It is shown that [bmim][BF4] and iron(III) chloride hexahydrate can be quantitatively recovered and be reused effectively for many times. Compared with the known methods, this novel process has the advantage of being an envkonmentally benign process together with good yields and mild reaction conditions.     

Ionic liquid media resulted in the first asymmetric aminohalogenation reaction of alkenes

[reaction: see text] The first asymmetric aminohalogenation of functionalized alkenes has been established. The ionic liquid [bmim][BF4] was found to be the only effective media for success as normal organic solvents failed to give any product for this reaction. The reaction is also very convenient to perform by simply mixing the three reactants, cinnamates, N,N-dichloro-p-toluenesulfonamide, and catalyst, together with 4 A molecular sieves at room temperature in [bmim][BF4] in any convenient vial of appropriate size without special protection from inert gases. Good chemical yields (60-72%) and diastereoselectivities (up to 75% de) have been obtained with a good scope of substrates. The resulting individual diastereomers have been cleanly separated via column chromatography. The absolute stereochemistry of the reaction was unambiguously determined by X-ray structural analysis.