Efficient and Eco-friendly Process for the Synthesis of Bi（indolyl）-methanes Catalyzed by Sodium Hydrogensulfate Monohydrate in Ionic Liquid n-Butylpyridinium Tetrafluoroborate

Indole fragment is featured widely in a wide variety of pharmacologically and biologically active compounds1. A large number of bi(indolyl)methanes have been reported to be isolated from terrestrial and marine natural sources, viz. parasitic bacteria, tun…     

Synthesis of a novel multi-SO<Subscript>3</Subscript>H functionalized ionic liquid and its catalytic activities

A novel multi-SO₃H functionalized ionic liquid is synthesized and a detailed account of its catalytic activities in acetalization and acetylation is given. The results showed that the ionic liquid is very efficient in the conventional acid-catalyzed reactions with good to excellent yields within a short reaction time. Operational simplicity, small amounts required, low cost of the catalyst, high yields, scalability and reusability are the key features of this methodology, which indicates the high potentialities of the novel ionic liquid to be used in environmentally friendly processes.     

Knoevenagel Condensation Catalyzed by 1,1,3,3‐Tetramethylguanidium Lactate

Knoevenagel condensation between malononitrile or ethyl cyanoacetate and carbonyl compounds could be effectively promoted by 1,1,3,3‐tetramethylguanidium lactate, a basic ionic liquid, under mild conditions. Good to high isolated yields could be obtained. The ionic liquid can enhance the reaction rates significantly even though it was used in catalytic amount. The ionic liquid could be prepared simply and reused efficiently.     

Reduction of Aldehydes and Ketones with Potassium Borohydride as Reductant

A series of aldehydes and ketones were reduced by potassium borohydride in an ionic liquid/water ([bmim]PF6/H2O) biphasic system to afford corresponding alcohol with high purity in excellent yields. The ionic liquid/water biphasic system could promote the chemoselectivity and the substituents such as nitro group and chlorine remained intact. Aromatic ketones were not as active as aromatic aldhydes and cyclic ketones owing to their higher steric hindrance. The ionic liquid could be recycled and reused. This protocol has notable advantages of no need of phase transfer catalyst and organic solvents, mild conditions, simple operation, short reaction time, ease work-up, high yields and recycling of the ionic liquid.     

Three-Component,One-Pot Synthesis of Benzo[b][1,4]oxazines in Ionic Liquid 1-Butyl-3-methylimidazolium Bromide

Benzo[b][1,4]oxazines have been synthesized in good to excellent yields in the presence of the ionic liquid 1-butyl-3-methylimidazolium bromide [bmim]Br under relatively mild conditions without any added catalyst, The method offers the advantages of good yields and short reaction times, and the ionic liquid can be easily separated from the product and reused.     

Novel biodegradable protonic ionic liquid for the Fischer indole synthesis reaction

Novel eco-friendly tetramethylguanidinium propanesulfonic acid trifluoromethylacetate ([TMGHPS][TFA]) ionic liquid was developed as catalyst and medium for the Fischer indole synthesis of a wide variety of hydrazines and ketones. The indole products were isolated in high yields and with minimal amounts of organic solvent. This reaction showed that [TMGHPS][TFA] can be regenerated and reused with reproducible yields without eroding the integrity of the ionic liquid.     

Green protocol for conjugate addition of thiols to alpha,beta-unsaturated ketones using a [bmim]PF6/H2O system

Alpha,beta-unsaturated ketones undergo conjugate addition rapidly with thiols in a hydrophobic ionic liquid [bmim]PF(6)/H(2)O solvent system (2:1) in the absence of any acid catalyst to afford the corresponding Michael adducts in high to quantitative yields with excellent 1,4-selectivity under mild and neutral conditions. The enones show enhanced reactivity in ionic liquids, thereby reducing reaction times and improving the yields significantly. The use of ionic liquids helps to avoid the use of either acid or base catalysts for this conversion. The recovered ionic liquid was reused four to five times with consistent activity.     

Ambiphilic dual activation role of a task-specific ionic liquid: 2-hydroxyethylammonium formate as a recyclable promoter and medium for the green synthesis of β-nitrostyrenes

A cost-effective task-specific ionic liquid, 2-hydroxyethylammonium formate, efficiently promotes the condensation of nitroalkanes with various aldehydes to produce β-nitrostyrenes in high to excellent yields at room temperature. This reaction does not involve any hazardous organic solvent and toxic catalyst. The ionic liquid is recovered and recycled for subsequent reactions. In addition, a novel mechanism has been proposed invoking ambiphilic dual activation influence of the ionic liquid.     

Effect of ionic liquids in unimolecular solvolysis reactions involving carbocationic intermediates

Solvolysis studies of pivaloyl triflate were performed using ionic liquid/methanol solvent mixtures. The rearranged carbocation intermediate reacts with methanol via nucleophilic attack or elimination of a proton. Relative amounts of products were determined through ¹H NMR analysis. For most ionic liquids, increasing the ionic liquid:methanol ratio leads to increased yields of elimination product. Product ratios vary based on Kamlet–Taft solvatochromic parameters of hydrogen bond donating and accepting ability of the ionic liquid.     

Basic Ionic Liquid： A Reusable Catalyst for Knoevenagel Condensation in Aqueous Media

IntroductionThe Knoevenagel condensation of aldehydes/ketones and activated methylene compounds is one ofthe most common synthetic methods to produce func-tionalized alkenes. Theα,β-unsaturated productsobtained by this method have been widely used as th…     

Room temperature ionic liquid promoted improved and rapid synthesis of 2,4,5-triaryl imidazoles from aryl aldehydes and 1,2-diketones or α-hydroxyketone

An improved and rapid one-pot synthesis of 2,4,5-triaryl imidazoles in a room temperature ionic liquid is described, which does not need any added catalyst. Different ionic liquids based on 1-n-butyl and 1,3-di-n-butyl imidazolium salts were screened and their efficacy in terms of acidity and polarity have been correlated with yields and reaction period. The one-pot methodology resulting in excellent isolated yields in short reaction times is characterized by simple work up procedures and efficient recovery and recycling of the ionic liquid, which acts as a promoter.     

离子液体/水混合溶剂促进芳醛与罗丹宁的缩合反应

在室温条件下, 离子液体1-正丁基-3-甲基咪唑四氟硼酸盐([bmim]BF₄)与水组成的混合溶剂能有效催化一系列芳醛与罗丹宁反应, 以80%～93%的产率生成相应的5-芳亚甲基-2,4-噻唑二酮. 离子液体[bmim]BF₄催化活性高, 反应在10～120 min内完成. 实验结果表明该法反应条件温和、产率高、反应时间短、后处理简单、离子液体可重复使用.     

Ionic Liquids as Reagent and Reaction Medium: Preparation of Alkyl Aryl Ethers

Summary. Room temperature ionic liquid, [bmIm]OH, is used as a green recyclable reaction medium and reagent for the alkylation of phenols in excellent yields. The recovered ionic liquid was reused five to six times with consistent activity.     

Knoevenagel reaction in [MMIm][MSO₄]: synthesis of coumarins

The ionic liquid 1,3-dimethylimidazolium methyl sulfate, [MMIm][MSO?], together with a small amount of water (the amount taken up by the ionic liquid upon exposure to air), acts efficiently as both solvent and catalyst of the Knoevenagel condensation reactions of malononitrile with 4-substituted benzaldehydes, without the need for any other solvent or promoter, affording yields of 92%-99% within 2-7 min at room temperature. When L-proline is used as an additional promoter to obtain coumarins from o-hydroxybenzaldehydes, the reaction also proceeds in high yields. Work-up is very simple and the ionic liquid can be reused several times. Some of the coumarins obtained are described for the first time.     

Facile Synthesis of Ureas in Ionic Liquid

The urea functional group is of importance in a wide range of biological compounds such as enzyme inhibitors1 and pseudopeptides2. Substituted ureas are widely applied in fine chemical industry, especially pesticides3 and pharmaceuticals4. Many investigations have been made to search for an efficient and practical method to synthesize ureas. The typical procedure for the synthesis of ureas is treating isocyanates with primary or secondary amines in organic solvents5. In the presence of trans…     

Synthesis of Ethyl Isoxazole‐3‐Carboxylates Using an Ionic Liquid as a Soluble Support

A regioselective 1,3‐dipolar cycloadditions of ionic liquid‐supported vinyl ethers, derived from ionic liquid‐supported α‐phenylselenomethyl ether, with ethyl cyanoformate N‐oxide gave supported isoxazoline derivatives, which were then cleaved from the ionic liquid support under mild acidic conditions to afford ethyl isoxazole‐3‐carboxylates. This new synthetic method is simple and efficient and the products are obtained in good yields.     

Ionic Liquid–Mediated Knoevenagel Condensation of Meldrum's Acid and Aldehydes

A simple, efficient, and green protocol for Knoevenagel condensation of Meldrum's acid and aldehydes in ionic liquid at room temperature without any catalyst is described. The reaction has been performed in different ionic liquids. The enhancement in the rate is observed in Brönsted acidic ionic liquid 1‐methylimidazolium trifluoroacetate [Hmim]Tfa, which furnishes quantitative yields with 4–30 min in most of the cases. Furthermore, ionic liquid is easily reused without any appreciable loss in activity.     

离子液体介质中一锅法合成2-氨基-4-苯基-6-(苯基硫基)-3,5-二氰基吡啶衍生物

考察了各种不同介质中,芳醛、丙二腈和苯硫酚为原料的一锅反应,发现在离子液体1-正丁基-3-甲基咪唑四氟硼酸盐([bmim]BF4)介质中,反应能够在较短时间内高产率地生成2-氨基-4-苯基-6-(苯基硫基)-3,5-二氰基吡啶衍生物,且没有1,4-二氢吡啶副产物的生成.该方法具有反应条件温和、产率高、选择性好和环境友好等优点,且离子液体容易回收,可循环使用.     

FeCl3-Catalyzed Pechmann Synthesis of Coumarins in Ionic Liquids

The synthesis of coumarin derivatives via Pechmann reaction using anhydrous FeCl₃ as Lewis acid catalyst in ionic liquid medium has been carried out. The best results were obtained (yields as high as 89%) with ionic liquids having bis(triflic)imide as a counteranion. The ionic liquid could easily be recovered and reused.     

Arylation of Sensitive 1-(Pyrrolidin-1-yl)-diazen-1-ium-diolate in Ionic Liquids

The purpose of this research was to investigate the stability and reactivity of 1-(pyrrolidin-1-yl)diazen-1-ium-1,2-diolate (PYRRO/NO) in dimethylformamide (DMF, as the reference solvent) and compare them to those obtained using different ionic liquids. The results of our experiments showed that PYRRO/NO is more stable (based on reactivity) in ionic liquid [EMIM][Ms] (with reaction yields up to 52%) than in DMF, that substitution products can be separated directly and quantitatively from the ionic liquid using a single flash-column separation, and that the ionic liquids can also be recovered and reused in a second iteration of the same reaction to achieve similar yields.