Baylis-Hillman reaction in [bdmim][PF6] ionic liquid

A new use of ionic liquid [bdmim][PF₆] as solvent for the Baylis-Hillman reaction is presented. Unlike the commonly used [bmim][PF₆] that evidently reacts with electrophilic aldehydes under basic conditions, ionic liquid [bdmim][PF₆] is inert and the Baylis-Hillman reaction in [bdmim][PF₆] proceeds smoothly with better yield.     

碱性离子液体的合成及其在Baylis-Hillman 反应中的应用

采用正交实验优化合成了碱性离子液体氢氧化1-丁基-4-二甲氨基吡啶盐, 以其为反应溶剂, 在催化剂DABCO(1,4-二氮杂二环[2.2.2]辛烷)作用下进行了芳香醛与丙烯酸甲酯的Baylis-Hillman 反应研究. 实验结果表明, 在该离子液体的存在下, 芳香醛与丙烯酸甲酯以较快的反应速度和较高产率生成目标化合物. 在此基础上, 进一步研究了水-离子液体复合体系对Baylis-Hillman 反应的影响, 取得了更快的速率及更高的产率.     

Baylis-Hillman Reaction Involving Substituted Cyclic Enones in Aqueous Media

β-Substituted enones have been considered less reactive in Baylis-Hillman reaction. The reaction of cyclicenones is sluggish or does not occur at all under traditional conditions. [1] Therefore, substituted cyclic enones havebeen less explored in Baylis-Hillman reaction due to the extremely low reactivity. In this communication, we reported Baylis-Hillman reaction of substituted cyclic enones using our previously developed conditions with imidazole as catalyst. The reaction proceeded smoothly in aqueous media affording the desired product with good yields and moderate diastereoselectivity.     

An unexpected highly diastereoselective double Baylis-Hillman reaction of per- (or poly)fluorophenyl aromatic aldimines with methyl vinyl ketone

Aza-Baylis-Hillman reaction of per- (or poly)fluorophenyl aromatic aldimines 1 with methyl vinyl ketone (MVK) was studied. It was found that both the used Lewis base and solvent can significantly affect the reaction. Using triphenylphosphine as a Lewis base, the reaction of 1 with MVK proceeded smoothly to give the normal Baylis-Hillman adduct 2 along with the double Baylis-Hillman adduct 3 as by-product in THF. When 1,4-diazabicyclo[2.2.2]octane was used as a Lewis base in DMF, the aza-Baylis-Hillman reaction of 1 with MVK gave the double aza-Baylis-Hillman adduct 3 exclusively in moderate to good yields with excellent diastereoselectivities. The double Baylis-Hillman adduct 3 was conveniently converted to fluorine-containing 4-alkylidene-2-cyclohexen-1-ones under mild reaction conditions in good yields.     

Salt effects on the Baylis-Hillman reaction

The Baylis-Hillman reaction is shown to accelerate in salt solutions of water and the ‘water-like’ structured solvents, like formamide and N-methylformamide in the presence of DABCO. Ethylene glycol, another structured solvent and its salt solutions fail to make any impact on the reaction rates. The salts that are conventionally defined as salting-out or -in do not behave in a similar fashion, when employed in the Baylis-Hillman reactions. The results are supported by solubility measurements. It seems that the cation, anion, nature of solvent and of reactants together ascertain whether a salt will enhance or retard the Baylis-Hillman reaction.     

Azoles: Effective Catalysts for Baylis-Hillman Reaction in Aqueous Media

β-Substituted enones have been considered less reactive in Baylis-Hillman reaction. The reaction of cyclic enones is sluggish or does not occur at all under traditional conditions. Various catalysts have been developed to pro mote the reaction of cyclic enones but with limited success. In previous study, we found that imidazole can catalyze the Baylis-Hillman reaction involving cyclic enones in aqueous THF solution. [1] In our continued efforts, a variety of azole compounds were examined in Baylis-Hillman reaction. We found that the azoles act as effective catalysts in properly adjusted water solution.     

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.     

甲醇溶剂中Baylis-Hillman反应机理的DFT研究

在B3LYP/6-311＋＋G**水平下计算研究了三甲胺催化的丙烯醛和甲醛在甲醇溶剂中的Baylis-Hillman反应, 甲醇溶剂效应采用超分子模型研究, 获得了反应中各物种的优化构型及其能量, 探讨了甲醇溶剂中Baylis-Hillman反应的微观过程.     

Successful Baylis-Hillman reaction of acrylamide with aromatic aldehydes.

Acrylamide and aromatic aldehydes were found to undergo the Baylis-Hillman reaction at ambient temperature in an aqueous medium in the presence of a stoichiometric amount of base catalyst, DABCO, to give the corresponding 3-hydroxy-2-methylenepropionamides in 61-99% yield. A faster competing, but reversible, non-Baylis-Hillman reaction was initially observed under the conditions to form N-acylhemiaminals, which later disappeared, as the desired Baylis-Hillman adduct was formed as the major product over an extended period of time (12-48 h). This represents the first demonstration of the Baylis-Hillman reaction of aldehydes with acrylamides, which were thought to be inert under atmospheric pressure and at ambient temperature.     

非传统介质中的Baylis-Hillman反应

Baylis-Hillman反应是一个为数不多的形成碳—碳键的原子经济反应, 因其产物富含官能团而成为非常有潜力的合成有机多功能分子的有力工具. 然而, 反应速度慢、反应产率低是该反应常遇到的问题. 为了克服这些缺点, 近年来, 许多新颖的溶剂被用于这个反应. 本文综述了这些方面的最新研究进展和发展趋势.     

丙烯醛和甲醛的Baylis-Hillman反应机理的DFT研究

采用密度泛函DFT-B3LYP方法在6-311++G**基组下计算研究了三甲胺催化的丙烯醛和甲醛的Baylis-Hillman反应的微观过程,获得了两种反应通道(分别对应于顺式-丙烯醛和反式-丙烯醛)的势能面.结合CH3OH溶剂效应,探讨了两种反应通道的微观机理.     

Baylis-Hillman reactions in aqueous acidic media

The Baylis-Hillman reaction has been successfully performed under aqueous acidic conditions at pH 1, using a range of substrates and tertiary amines as catalysts.     

Hydroxy-assisted catalyst-free Michael addition-dehydroxylation of Baylis-Hillman adducts in poly(ethylene glycol)

Intramolecular hydrogen bonding facilitates nucleophilic addition of sulfones to Baylis-Hillman adducts in a single step to realize the substituted allyl sulfones. The reaction is performed in PEG (400 MW) as solvent, which allows easy solvent recycling.     

Palladium-catalyzed cross-coupling of Baylis-Hillman acetate adducts with organosilanes

[Reaction: see text]. A cross-coupling reaction between acetates of Baylis-Hillman adducts and organosilanes is described. A nonconventional solvent poly(ethylene glycol) (PEG) is used as the reaction medium.     

Baylis-Hillman反应机理研究进展

介绍了一种形成碳—碳键的方法——Baylis-Hillman反应, 综述了单分子醛、双分子醛反应机理、TiCl₄催化机理、不对称诱导机理以及低温效应、溶剂效应、离子液体反应机理的研究进展.     

Imidazoles: Effective Catalysts for Baylis-Hillman Reaction in Aqueous Media

β-Substituted enones have been considered less reactive in Baylis-Hillman reaction. The reaction of cyclic enones is sluggish or does not occur at all under traditional conditions. Various catalysts have been developed to pro mote the reaction of cyclic enones but with limited success. In previous study, we found that imidazole can catalyze the Baylis-Hillman reaction involving cyclic enones in aqueous THF solution.[1] In our continued efforts, we screened a variety of imidazoles to develop superior catalyst, and we found that the reaction could be greatly accelerated by adjusting the pH value of the water solution.     

液态聚乙二醇作为绿色反应介质在有机反应中的应用

低分子量的液态聚乙二醇（PEG）作为一种新型的绿色有机反应溶剂正受到人们的极大关注。PEG具有好的热稳定性、不挥发、不易燃、无毒、生物可降解、廉价易得,以及易于回收和循环使用。此外,PEG可以溶解众多的有机化合物和有机金属配合物。因此,PEG作为有机溶剂的替代品和作为均相催化剂的载体已经成功地应用到许多有机反应中,它们包括还原反应、氢化反应、氧化反应、不对称双羟基化反应、Heck反应、Suzuki交叉偶联反应、Michael加成反应、不对称Aldol反应、Baylis-Hillman反应、脂肪酶催化的反应和聚合反应等。本文对这一领域的研究进展作一综述。     

First diastereoselective intramolecular Baylis-Hillman reaction: an easy access to chiral alpha-methylene-beta-hydroxylactones

The first diastereoselective intramolecular Baylis-Hillman reaction of chiral substrates is reported wherein both aldehyde and activated olefin coexist as substituents to afford alpha-methylene-beta-hydroxylactones in good yields exclusively as single isomers under the standard base-catalyzed reaction conditions in CH(2)Cl(2). Formation of alkoxylactones by an in situ derivatization of adducts was also observed.     

A FACILE CONVERSION OF THE BAYLIS-HILLMAN ADDUCTS INTO TRIMETHYLSILYL ETHERS WITH HEXAMETHYLDISILAZANE CATALYSED BY IODINE

The hydroxy group of the Baylis-Hillman adducts was protected with trimethylsilyl (TMS) group using the reaction of adducts 1a–h with hexamethyldisilazane (HMDS) catalyzed by iodine under nearly neutral reaction conditions.     

Studies on montmorillonite K10-microwave assisted isomerisation of Baylis-Hillman adduct. Synthesis of E-trisubstituted alkenes and synthetic application to lignan core structures by vinyl radical cyclization

The isomerisation of acetates from the Baylis-Hillman adducts with Mont.K10 clay-microwave combination furnished E-trisubstituted alkenes in high yield. The simple Baylis-Hillman adducts with trimethyl orthoformate and unsaturated alcohols under clay catalytic condition gave densely functionalised-isomerized products under solvent free condition. Application of the propargyl derivatives thus obtained from the isomerisation of the Baylis-Hillman adducts with propargyl alcohol has been demonstrated in the synthesis of lignan core structures by tri-n-butyltin hydride mediated vinyl radical cyclization.