Poly(ethyleneglycol) (PEG): a rapid and recyclable reaction medium for the DABCO-catalyzed Baylis-Hillman reaction

PEG (400) has been used as a rapid and recyclable reaction medium for the Baylis-Hillman reaction with the conventional basic catalyst DABCO (20 mol %) with very good yields of products. Recyclability is achieved with no further addition of DABCO to the reaction medium for over four runs without substantial loss in yields. Incidentally, DABCO is recycled for the first time in this transformation.     

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.     

Reexamination of the traditional Baylis-Hillman reaction

In the Baylis-Hillman reaction of arylaldehydes with methyl vinyl ketone (MVK), we found that, besides the normal Baylis-Hillman adduct 1, the diadduct 2 can also be formed at the same time and the yield of 2 can reach to 55% if increasing the amount of methyl vinyl ketone. But for ethyl vinyl ketone (EVK), methyl acrylate or acrylonitrile, only the normal Baylis-Hillman adduct 4, 7 or 8 was obtained, respectively. The substituent's effects and Lewis base effects were also examined and a plausible reaction mechanism was proposed for the formation of 2.     

A novel ytterbium/perfluoroalkylated-pyridine catalyst for Baylis-Hillman reaction in a fluorous biphasic system

Ytterbium perfluorooctanesulfonate [Yb(OPf)₃] catalyses the highly efficient Baylis-Hillman reaction in the presence of a catalytic amount of a novel perfluoroalkylated-pyridine as a ligand in a fluorous biphasic system (FBS) composed of toluene and perfluorodecalin. The new process can be carried out successfully without the use of a stoichiometric amount of Lewis base. The fluorous phase containing the active catalytic species is easily separated and can be reused several times without significant loss of catalytic activity.     

Baylis-Hillman chemistry: a one pot cross-coupling/allylboration reaction

A one pot sequential cross-coupling/allylboration is described. Baylis-Hillman acetate adducts couple with bis(pinacolato)diboron to form substituted allylboronates, which react with aldehydes in the presence of a silica supported BF₃ catalyst to form highly functionalized homoallylic alcohols in excellent yields.     

The first one-pot oxidative Michael reaction of Baylis-Hillman adducts with indoles promoted by iodoxybenzoic acid

Baylis-Hillman adducts undergo smooth, one-pot oxidative conjugate addition with indoles in the presence of 2-iodoxybenzoic acid (IBX) under neutral conditions to afford a new class of substituted indoles in good yields.     

Fast diastereoselective Baylis-Hillman reaction by nitroalkenes: synthesis of di- and triene derivatives

The Baylis-Hillman reaction is performed using nitroalkenes as activated alkenes, ethyl-2-bromomethylacrylate as electrophilic acceptor and DBU as catalyst base. Nitro dienes are obtained in good yields and very short reaction times. Moreover, starting from appropriate nitroalkenes it is possible to realize one pot the synthesis of trienic systems.     

The Baylis-Hillman reaction: a strategic tool for the synthesis of higher-carbon sugars

The Baylis-Hillman reaction of acyclic sugar-derived aldehydes is invoked as an attractive synthetic strategy for ready access to higher-carbon sugars.     

CH3ReO3/H2O2 in room temperature ionic liquids: an homogeneous recyclable catalytic system for the Baeyer-Villiger reaction

The Baeyer-Villiger oxidation of cyclic ketones can be effected by methyltrioxorhenium/hydrogen peroxide in the ionic liquid [bmim]BF₄. After simple extraction of the lactone with diethyl ether, the catalyst can be repeatedly recycled and efficiently reused for the lactonisation process in the same reaction medium.     

Diastereoselective Baylis-Hillman reaction using N-glyoxyloyl camphorpyrazolidinone as an electrophile: synthesis of optically pure 2-hydroxy-3-methylene succinic acid derivative

The camphorpyrazolidinone derived N-glyoxylate was efficiently prepared and used as an electrophile in the Baylis-Hillman reaction under classical DABCO catalyzed conditions. The corresponding 2-hydroxy-3-methylene succinic acid derivative was generally obtained with excellent diastereoselectivity and moderate chemical yields (51-75%).     

Hydroxyl ionic liquid (HIL)-immobilized quinuclidine for Baylis-Hillman catalysis: synergistic effect of ionic liquids as organocatalyst supports

Hydroxyl ionic liquid (HIL) has been explored as a novel support for Baylis-Hillman catalyst. The HIL-supported catalyst showed a better catalytic activity compared to other IL-immobilized catalyst that has no hydroxyl group attached to the IL scaffold. The hydroxyl group linked on IL played an important role in facilitating efficient catalysis under solvent-free conditions. The corresponding Baylis-Hillman and aza-Baylis-Hillman adducts were obtained in good to excellent yields in all cases examined. The HIL-supported quinuclidine can be readily recovered and reused for six times without significant loss of catalytic activity.     

Synthesis and characterization of hybrid materials based on 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid and Dawson-type tungstophosphate K7[H4PW18O62]·18H2O and K6[P2W18O62]·13H2O

In this study, we synthesized hybrid materials using well-Dawson polyoxometalates (POMs), K₇[H₄PW₁₈O₆₂]·18H₂O or K₆[P₂W₁₈O₆₂]·13H₂O and a room temperature ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF₄]). K, W, P and CHN elemental analysis showed that one mole of [H₄PW₁₈O₆₂]⁷⁻ reacts with 6 moles of BMIM⁺ and one mole of [P₂W₁₈O₆₂]⁶⁻ reacts with 4 moles of BMIM⁺ to form, respectively, K[BMIM]₆H₄PW₁₈O₆₂ and K₂[BMIM]₄P₂W₁₈O₆₂. X-ray diffraction illustrated amorphous structure of the hybrid materials. FT-IR spectra showed the presence of both 1-butyl-3-methylimidazolium cation and the Dawson anion. TG analysis displayed a relative thermal stability of the hybrid materials compared to the parents Dawson POMs. Cyclic voltammetry showed that the reduction peak potentials of the Dawson anion in the hybrid materials shift towards negative values and the shift is more pronounced for K[BMIM]₆H₄PW₁₈O₆₂ compared to K₂[BMIM]₄P₂W₁₈O₆₂. This was attributed to a decrease in the acidity of the Dawson POM anion in the hybrid material.     

Protic guanidinium ionic liquid as a green and highly efficient catalyst for the synthesis of functionalized spirochromenes under solvent-free conditions

A simple and efficient method for the synthesis of functionalized spirochromenes is explained using protic guanidinium ionic liquid as a catalyst under solvent-free conditions at room temperature. This procedure is simple, clean, and excellent yields are obtained in short reaction times.     

A simple,efficient thermally promoted protocol for Huisgen-click reaction catalyzed by CuSO4·5H2O in water

A thermally promoted and CuSO₄-catalyzed new version of the Huisgen-click reaction is presented in this Letter. Notably, this protocol was suitable not only for the reactions between organic azides and alkynes, but also for one-pot three-component reactions among alkyl halides, NaN₃, and alkynes.     

Remarkable rate acceleration of water-promoted nucleophilic substitution of Baylis-Hillman acetate: a facile and highly efficient synthesis of N-substituted imidazole

Without additional reagents, the Baylis-Hillman acetates 2 underwent nucleophilic substitution reaction with imidazole readily in aqueous THF solution to afford the corresponding N-substituted imidazole derivatives 3 in good to excellent yields. Moreover, the reaction between the in situ generated DABCO salt of Baylis-Hillman acetates 4 and imidazole occurs in aqueous THF providing the S_N2 type products 5. The simpler operational procedure, better stereoselectivity and higher efficiency over conventional method make the present protocol practical for the preparation of imidazole derivatives.     

1-Benzopyran-4(4H)-ones as novel activated alkenes in the Baylis-Hillman reaction: a simple and facile synthesis of indolizine-fused-chromones

1-Benzopyran-4(4H)-one derivatives have been successfully employed as novel activated alkenes in the Baylis-Hillman coupling with heteroaromatic-aldehydes, nitrobenzaldehydes and isatin-derivatives and the corresponding adducts, derived from pyridine-2-carboxaldehyde, have been transformed into a novel indolizine-fused-chromone framework.     

Simple and one-pot synthesis of tri and tetracyclic frameworks containing [1,8]naphthyridin-2-one moiety from the Baylis-Hillman adducts

A facile synthesis of tri and tetracyclic frameworks containing [1,8]naphthyridin-2-one skeleton from the Baylis-Hillman alcohols via the Johnson-Claisen rearrangement, followed by the treatment with Fe/AcOH in simple one-pot multi-step process is described.     

综合创新设计实验:“均相反应、异相回收”[PIMPS]H2PW12O40双功能催化剂在酯化、氧化反应中的应用*

磺酸类离子液体及多酸催化剂是近年来应用广泛的2类高效环境友好型催化剂,实现2类催化剂组装成单组分双功能化环保型催化剂并运用到大学有机化学实验中,替代现行实验中常用的强腐蚀性、强氧化性的浓硫酸,是未来实验内容改革的方向之一。本实验合成的[PIMPS]H₂PW₁₂O₄₀(PIMPS=1-丙基-3-磺酸基丙基咪唑磺酸盐)催化剂经¹H NMR、IR确证了结构,并将其应用于苯甲酸乙酯合成、苯甲硫醚氧化反应中。实验结果表明,此单组分催化剂具有酸催化、氧化催化双功能特性,催化效果良好,具有可重复使用、无腐蚀性等显著优点。在催化反应中兼具均相催化和非均相催化特点,催化剂能够实现在反应体系中的均相反应、异相回收。通过此实验的开展,培养了学生依据绿色化学理念发现问题、解决问题的创新能力和创新意识,有利于学生深入理解单组分双功能催化剂的概念,有效地达到理论和实践的有机结合。     

Fructose-derived ionic liquids: recyclable homogeneous supports

A new homogeneous support has been developed that is based on a fructose-derived ionic liquid. It has been applied to the preparation of a series of supported Diels-Alder adducts. The cleavage of these adducts from the ionic liquid has resulted in some interesting observations regarding the base stability of imidazolium cations. Using a transesterification cleavage, the ionic support can be recovered and recycled.     

Synthesis of 1,2-azidoalcohols from epoxides using a task-specific protic ionic liquid: 1-hydrogen-3-methylimidazolium azide

A task-specific ionic liquid as an environmentally eco-friendly green catalyst has been synthesized and used in the ring opening of epoxides under green conditions. In order to use protic ionic liquids (PIL), we decided to synthesize 1,2-azidoalcohols via a ring opening reaction of epoxides with 1-hydrogen-3-methylimidazolium azide ([Hmim]N₃), which actually acts as a solvent, a reagent and an activator of the epoxide ring. The reaction was carried out in short times (50–70 min) at 70 °C to give 1,2-azidoalcohol in 80–94% isolated yields.