The Morita-Baylis-Hillman reaction in aqueous-organic solvent system

We have found that water and organic solvents mixed at different proportions can give good to excellent yields and short reaction times for the Morita-Baylis-Hillman reaction. The present Letter details our findings in the Morita-Baylis-Hillman reaction between several aromatic aldehydes and methyl acrylate or acrylonitrile. The selection of the catalyst was also evaluated and DABCO affored the best results when compared to DBU, DMAP, HMT, Imidazole and Triethylamine.     

Improved catalysis of Morita-Baylis-Hillman reaction. The strong synergic effect using both an imidazolic ionic liquid and a temperature

The effect of different catalytic conditions for the Morita-Baylis-Hillman reaction has been evaluated both experimentally and by chemometry. The use of either ultrasound at 0 °C, ultrasound with an imidazolic ionic liquid at 0 °C or the ionic liquid catalyst at 0 and 50 °C was systematically tested. A strong synergic effect, which significantly increases the reaction rates and yields, was observed when the reactions were performed using an imidazolic ionic liquid catalyst at both 0 and 50 °C.     

Thiourea-catalyzed Morita-Baylis-Hillman reaction

Here, we describe our studies on the thiourea-catalyzed Morita-Baylis-Hillman (MBH) reaction. Chemoselective activation of carbonyl compounds via hydrogen bonding to thiourea as a catalyst is the key to drastic rate acceleration of this reaction. The application of chiral bis-thiourea-type organocatalysts, which can form a chiral double hydrogen-bonding network, is effective for enantioselective MBH reaction. A cooperative system of bis-thiourea compounds, synthesized from 1,2-diaminocyclohexane, and a Lewis base effectively promotes the MBH reaction at lower temperature, affording the MBH adducts in 33-95% yield with 44-90% ee. A plausible transition state model of the enantioselective MBH reaction is presented.     

Polymeric ionic liquid as novel catalyst for the Prins reaction

A series of micro-mesoporous polymeric ionic liquids (PILs) have been successfully synthesized by the method of anion and cation copolymerization. Then use FT-IR, N₂ adsorption–desorption isotherms, SEM, and TG to characterize them. Furthermore, the catalytic performance of the synthesized PILs was investigated for the Prins reaction of propylene with 1, 3, 5-trioxane. Among the four PILs synthesized, VIMBs-DVB-SSA has better catalytic activities for the Prins reaction. Under the optimal conditions, 100 °C, 8 wt%, 4 h and n (propylene)/n (1, 3, 5-trioxane) = 4:1, the conversion of formaldehyde (99.8%) and selectivity (81.7%) for 4-methyl-1, 3-dioxane. In addition, the effects of reaction time, catalyst dosage, and reaction temperature and mole ratio of reaction substrates on the reaction were also investigated. The prepared catalyst had good thermal stability and can be reused easily.     

季膦离子液体促进的Morita-Baylis-Hillman反应

膦类离子液体,因其好的热稳定性以及在弱碱性介质中的惰性等优异特点,正在受到越来越多的关注.以廉价的三丁基膦和各种卤代烃为原料,制备了一系列季膦离子液体,然后以其与水组成的复合体系为反应介质,在催化剂1,4-二氮杂二环[2.2.2]辛烷(DABCO)作用下,进行了各种醛与丙烯腈、丙烯酸甲酯及丙烯酰胺的Morita-Baylis-Hillman反应研究.实验结果表明,在室温条件下,溴化乙基三丁基膦与水组成的复合溶剂体系,有效地促进了各种芳香醛及脂肪醛的Morita-Baylis-Hillman反应,不仅反应速度快,而且目标产物产率高.     

α-Hydroxymethylation of conjugated nitroalkenes via the Morita-Baylis-Hillman reaction

The Morita-Baylis-Hillman reaction (MBHR) of conjugated nitroalkenes has been successfully carried out for the first time. A variety of aromatic and heteroaromatic nitroalkenes react with formaldehyde at room temperature in the presence of stoichiometric amounts of imidazole and catalytic amounts of anthranilic acid in THF providing moderate to good yields of the multifunctional adducts in most of the cases.     

Diels-Alder reaction in protic ionic liquids

Protic imidazolium ionic liquids have been tested as reaction media in the Diels-Alder reaction between cyclopentadiene and two dienophiles (dimethyl maleate and methyl acrylate). Good conversions and endo/exo selectivities were achieved. The activation of the dienophile by hydrogen bonding with protic imidazolium ILs was demonstrated.     

Selenonium ionic liquid as efficient catalyst for the Baylis-Hillman reaction

The new acidic ionic liquid phenyl butyl ethyl selenonium tetrafluoroborate, [pbeSe]BF₄, was successful used as a co-catalyst in the Baylis-Hillman reaction of aldehydes and electron-deficient alkenes. The Baylis-Hillman adducts were obtained in moderated to good yields and in relatively short reaction times under mild conditions.     

An imidazolium tosylate salt as efficient and recyclable catalyst for acetylation in an ionic liquid

A novel non-metallic salt, 1-butyl-3-methylimidazolium tosylate ([bmim][OTs]) dissolved in the ambient temperature ionic liquid of 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF₄]), was found to be the efficient catalyst for acetylation with the advantages of good recyclability, avoidance of metal contamination, mild reaction conditions, and wide availability for substrates (alcohols, phenols, and amines), could completely replace organic bases, metal Lewis acids, or metallic triflates to fulfill acetylation by a nucleophilic catalytic mechanism, which was supported by ¹³C NMR analysis. Correspondence: Ye Liu, Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Chemistry Department of East China Normal University, Shanghai 200062, China.     

Polystyrene-supported chloroaluminate ionic liquid as a new heterogeneous Lewis acid catalyst for Knoevenagel condensation

Non-hygroscopic polystyrene-supported chloroaluminate ionic liquid was prepared from the reaction of Memfield resin with 1- methylimidazole followed by reaction with aluminum chloride.This Lewis acidic ionic liquid is environmentally friendly heterogeneous catalyst for the Knoevenagel condensation of aromatic and aliphatic aldehydes with ethyl cyanoacetate.The catalyst is stable(as a bench top catalyst) and reusable.     

Chloride based ionic liquids as promoting agents for Meerwein reaction in solventless conditions

Chloride based ionic liquids were used as chloride source in Meerwein reaction either in [bmim]X (bmim = 1-butyl-3-methylimidazolium, X = BF₄, PF₆) as solvents or in solventless conditions. Satisfactory yields (49-71%) with diversely substituted diazonium salts were achieved by using 1,3-dibutylimidazolium chloride in the presence of a bimetallic Zn/Cu catalyst.     

A substrate controlled, very highly diastereoselective Morita-Baylis-Hillman reaction: a remote activation of the diastereofacial selectivity in the synthesis of C-3-branched deoxysugars

The Morita-Baylis-Hillman (MBH) reaction of p-nitrobenzaldehyde with C (6) acyl protected enuloside 1 in the presence of TiCl₄/TBAI yielded highly diastereoenriched C-3-branched deoxysugar derivative or MBH adduct 1′a in high yield, while reactions of unprotected enuloside 2a and C (6) alkyl protected enulosides 2d-e with p-nitrobenzaldehyde under the same conditions afforded the adducts 2′a and 2′d-e, respectively, in low yield with moderate selectivity. Several representative aromatic and aliphatic aldehydes were selected to undergo MBH reaction with 1 to give their respective adducts in very good yield with a very high diastereoselectivity. A plausible mechanism based on the assumption of a Zimmerman-Traxler-type transition state was proposed to explain the excellent selectivity observed with adducts derived from 1. The synthetic application of these adducts were shown by their stereoselective reduction to corresponding threo isomers in very good yield.     

Thiazolinium salt: an efficient catalyst for the Mukaiyama reaction

Mukaiyama aldol reaction between benzaldehyde and Danishefsky diene is promoted by ionic liquid-type salts. Hence, thiazolinium salts have been found to be the most efficient for this transformation. On a mechanistic point of view, only the Mukaiyama process is observed without any hetero Diels-Alder cycloaddition. In some cases, cyclisation of the Mukaiyama adduct occurred without addition of TFA. Interestingly, the thiazolinium catalyst can be recycled at least 10 times without loss of activity.     

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.     

A green and novel procedure for the preparation of ionic liquid

A green and novel procedure is described for the preparation of a series of ionic liquid containing alkylimidazolium-based or N-alkylpyridinium-based cations and hexafluorophosphate-based or tetrafluoroborate-based anions in one-pot solvent-free conditions to give excellent yields with shortened time.     

A facile and economical procedure for the synthesis of maleimide derivatives using an acidic ionic liquid as a catalyst

Seven maleimide derivatives were synthesized in good yields and high purity from the corresponding maleamic acids using a Brønsted acidic room temperature ionic liquid (RTIL) as a catalyst. The products were obtained through merely a decanting and removal of the solvent, suggesting that this procedure is superior to the conventional routes, in which the strong organic/inorganic acids were used as the catalysts, as well as a complicated post-processing procedure for the separation and purification of the products was employed.     

An efficient,recoverable fluorous organocatalyst for accelerating the DABCO-promoted Morita-Baylis-Hillman reaction

A convenient method for Morita-Baylis-Hillman reaction of arylaldehydes with methyl acrylate has been developed by using fluorous-tag organocatalyst 1-[4-(perfluorooctyl)phenyl]-3-phenylthiourea and DABCO at room temperature.The fiuorous, organocatalyst could be recovered from the reaction mixture by fiuorous solid-phase extraction(F-SPE) with excellent purity for direct reuse.     

Enantioselective Morita-Baylis-Hillman (MBH) reaction promoted by a heterobimetallic complex with a Lewis base

A new double-activation catalysis is presented for the Morita-Baylis-Hillman (MBH) reaction of an α,β-unsaturated ketone and an aldehyde by the combined use of a heterobimetallic asymmetric complex and tributylphosphine ((n-Bu)₃P) to afford the α-methylene-β-hydroxy ketone with up to 99% ee.     

First application of chiral ionic liquids in asymmetric Baylis-Hillman reaction

The first example of the use of chiral ionic liquids as reaction media in the asymmetric Baylis-Hillman reaction was described using N-alkyl-N-methylephedrinium salts. Good yields and significant enantiomeric excesses were obtained.