One-step,synthesis of Hantzsch esters and polyhydroquinoline derivatives using new organocatalyst

Herein we report an efficient organocatalyst for the multicomponent Hantzsch reaction under mild condition.The product easily isolated by simple filtration and catalyst can be recovered.

Enantioselective Aldol Reactions and Michael Additions Using Proline Derivatives as Organocatalysts

Six compounds including five proline derivatives have been prepared and tested as chiral organocatalysts for enantioselective aldol reactions and Michael additions. The enantiomeric excesses, which are highly dependent on the molecular structure of catalysts as well as experimental conditions, have reached over 98%.

Carbohydrate-Derived Organocatalysts for the Reduction of Imines with Trichlorosilane

The backbone of D-glucosamine hydrochloride was fine-tuned and modified by protecting the hydroxyl groups. In order to reduce imines with trichlorosilane, the carbohydrate-derived organocatalysts were prepared and screened. Methyl-4,6-O-benzylidene-2-amino-2-deoxy-α-D-glucopyr anoside was found as the best catalyst. The reduction was proceeded under CHCl3 as solvent at 40?C, affording 68% - 94% yield.

Stereoselective Aldol Reaction in Aqueous Solution Using Prolinamido-Glycosides as Water-Compatible Organocatalyst

Prolinamido-glycoside catalyzed asymmetric aldol reaction in aqueous media is reported. The reactions are rapid and highly stereoselective when water is used as solvent. The stereoselectivities were under influence of configurations of a prolyl residue of the catalyst and α-chiral aldehydes. Water soluble prolinamido-glycoside catalysts are easily separable from reaction mixture and can be recycled and re-used several times.

Highly active organocatalyst from a trivalent phosphazenium salt for ring-opening copolymerization of epoxides and cyclic anhydrides enhanced by hydrogen bonding interactions

It is highly desirable to develop simple organocatalysts for the controlled ring-opening alternating copolymerization(ROAC)of epoxides and cyclic anhydrides,leading to high molecular weight polyesters.Hence,a phosphazenium salt,namely tri[tris(dimethylamino)phosphoranylidenamino]phosphonium chloride(P_(4)^(+)Cl^(-)),is developed as a catalyst for the ROAC of epoxides and cyclic anhydrides.Surprisingly,the combination of P_(4)^(+)Cl^(-)with a protonic initiator,such as 1,4-benzenedimethanol(BDM)exhibited high efficiency in the copolymerization of propylene oxide(PO)and phthalic anhydride(PA).This led to the production of polyester with an exceptional high molecular weight(M_n)of up to 126 k Da,which represented a rare example of poly(PO-alt-PA)with Mnsurpassing 100 k Da.Note that the core P atom is trivalent status and the tris[tris(dimethylamino)]phosphoranyl group will share one proton in the P_(4)^(+)Cl^(-)salt.Once combined with protonic species,the P_(4)^(+)Cl^(-)will not only serve as a proton acceptor but also as a hydrogen bonding donor for the cyclic anhydrides.Therefore,it was assumed that the P_(4)^(+)plus proton served dual role in mimic of base/urea pair to effectively catalyze ROAC,which was supported by density functional theory(DFT)calculations.

TBAI辅助三嗪聚合物催化CO_(2)与环氧氯丙烷环加成反应机理的理论研究

二氧化碳排放量的增加对环境造成了重大威胁。利用含氮和卤素的有机催化剂可以催化CO_(2)与环氧化物的环加成反应。用ωB97X-D/def2-TZVP//ωB97X-D/def2-SVP方法,结合SMD溶剂化模型,计算了三嗪骨架聚合物催化剂与四丁基碘化铵(TBAI)助催化剂的复合催化体系(Cat-I)催化CO_(2)与环氧氯丙烷(ECH)加成为环碳酸酯的详细反应机理。计算结果显示,在Cat-I的催化作用下,ECH先活化的路径为最低能量路径。亚胺基氢键供体活化ECH中的C-O键,I-的强亲核性和离去能力协同作用促进反应的进行。其决速中间体(TDI)为起始反应物,决速过渡态(TDTS)为碳酸半酯的闭环步骤的过渡态,表观自由能垒为33.54 kcal/mol,比无助催化剂时的能垒低16.55 kcal/mol。这与105℃、常压下、TBAI为助催化剂时三嗪骨架聚合物催化目标反应的转化率为100%,而无助催化剂时转化率仅为70%的实验事实相符。

Potassium phthalimide:An efficient and green organocatalyst for the synthesis of 4-aryl-7-(arylmethylene)-3,4,6,7-tetrahydro-1Hcyclopenta[d]pyrimidin-2(5H)-ones/thiones under solvent-free conditions

An efficient synthesis of Biginelli-type compounds using potassium phthalimide as a green, mild, and commercially available organocatalyst in a one-pot, multi-component cyclocondensation reaction of cyclopentanone, aldehydes, and urea/thiourea is reported. The present methodology is a green approach to access 4-aryl-7-（aryImethylene）-3,4,6,7-tetrahydro-1H-cyclopenta[d]pyrimidin-2（5H）-ones/thiones. It offers several merits such as simple operational procedures, no use of hazardous organic solvents, and cheap and environmentally friendly solid basic catalyst.

An Efficient Asymmetric Domino Reaction of Amino Aldehyde to β,γ-Unsaturated a-Keto Esters Using trans-Perhydroindolic Acid as a Chiral Organocatalyst

An efficient asymmetric domino reaction of amino aldehyde to β,γ-unsaturated a-keto esters was achieved by using trans-perhydroindolic acid ld as a chiral organocatalyst with excellent asymmetric behavior. Under the opti- mal reaction conditions, products with more than 99% de and up to 93% ee were obtained in high chemical yield （up to 98%） for a series of β,γ-unsaturated a-keto esters. The methodology provided an efficient route to dihydro- pyran derivatives containing many substituent groups （including amino groups）.

Novel supramolecular organocatalysts of hydroxyprolinamide based on calix[4]arene scaffold for the enantioselective Biginelli reaction

A series of novel supramolecular organocatalysts of hydroxyprolinamide based on the upper rim of calix[4]arene scaffold have been developed to catalyze enantioselective multi-component Biginelli reaction. Under the optimal conditions, the reactions occurred with moderate-to-excellent enantioselectivities (up to 98% ee). A plausible transition state constructed by the supra- molecular interaction of hydrogen bond and cation-π between catalysts and substrates has been proposed.

A family of novel bifunctional organocatalysts:Highly enantioselective alcoholysis of meso cyclic anhydrides and its application for synthesis of the key intermediate of P2X_7 receptor antagonists

A family of novel squaramides/sulfamides based on 1,2-alkamine was developed as chiral bifunctional catalysts to promote the asymmetric alcoholysis of meso cyclic anhydrides. The hemiesters were obtained in high yield with up to 93% ee. The usefulness of this methodology was demonstrated in the asymmetric synthesis of the key intermediate of P2X7 receptor antagonists.

Lewis base-CO2 adducts as organocatalysts for CO2 transformation

In the recent decade, the development and application of organocatalysis for CO_2 transformation into useful chemicals have attracted much attention. Among these organocatalysts, Lewis base-CO_2 adducts(LB-CO_2) were found to be more efficient.The used Lewis base has great effect on the catalytic activity of its CO_2 adduct. This review reports the recent progress in LB-CO_2 adducts catalyzed the cyclization of CO_2 with epoxides or aziridines to afford cyclic carbonates or oxazolidinones,the carboxylation of CO_2 with propargylic alcohols to α-alkylidene cyclic carbonates, and the reduction of CO_2 to methanol,formamides and methylamines, with the focus on the catalytic mechanism.

Highly Efficient Asymmetric Synthesis Usomg Organocatalyst Derived From(S)-proline

1 Results Much effort has been focused on organocatalytic asymmetric synthesis in these several years. We have already documented highly efficient organocatalytic asymmetric acylation of a wide variety of racemic alcohols and meso-diols catalyzed bya chiral 1,2-diamine derived from (S)-proline[1]. (S)-Homoproline seems to be a potentially interesting organocatalyst, but no examples using (S)-homoproline itself in asymmetric synthesis has been reported. We have accomplished an efficient and practical syn...

Imidazol-1-yl-acetic acid as a novel green bifunctional organocatalyst for the synthesis of 1,8-dioxooctahydroxanthenes under solvent-free conditions

Imidazol-1-yl-acetic acid is introduced as a new, efficient and recyclable green bifunctional organocatalyst for the synthesis of 1,8-dioxooctahydroxanthenes under solvent-free conditions. This catalyst is water soluble and can be separated from the products by simple filtration. The filtrate can be evaporated to dryness and recrystallized from cool methanol to give the recovered catalyst. This organocatalyst was used for the synthesis of 1,8-dioxooctahydroxanthenes under solvent-flee conditions and recycled up to 8 consecutive runs without any losing of its efficiency.

Asymmetric Aldol Reaction Catalyzed by Modularly Designed Organocatalysts

The self-assembly of the precatalyst modules, which are amino acids and cinchona alkaloid derivatives, leads to the direct formation of the desired organocatalysts without any synthesis. These modularly designed organocatalysts （MDOs） may be used for catalyzed asymmetric aldol reaction the corresponding aldol products may be obtained in mediocre diastereoselectivities （up to 79 ： 21 dr）. Depending on structure of the aldehyde substrates, to excellent ee values （up to 92% ee） with moderate

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 fluorous organocatalyst could be recovered from the reaction mixture by fluorous solid-phase extraction （F-SPE） with excellent purity for direct reuse.

Recent advances in gold-complex and chiral organocatalyst cooperative catalysis for asymmetric alkyne functionalization

Homogeneous gold catalysis has demonstrated the preponderant capability of realizing a broad range of synthetically versatile alkyne functionalization over the last two decades.Though catalytic asymmetric alkyne transformation has focused on the principle of using gold catalysts either associated with chiral phosphine ligand or combined with chiral counterion,a variety of breakthroughs have been reported with the application of gold-complex and chiral organocatalyst cooperative catalysis strategy,which could enable the challenging transformations that cannot be realized by mono-catalysis with excellent stereoselectivity.This review will cover two general protocols in this field,including relay catalysis and synergistic catalysis,with emphasis on the detailed cooperative catalysts models to illustrate the roles of the two catalysts and highlight the potential synthetic opportunities offered by asymmetric cooperative catalysis.

Chiral N-formyl amino alcohol as Lewis basic organocatalyst for enantioselective hydrosilylation of ketimines

Easily accessible (1R,2S)-1,2-diphenyl-2-formamidoethanol has been developed as an effective Lewis base catalyst in the enantioselective hydrosilylation of ketimines, affording high isolated yields (up to 94%) and moderate to high enantioselectivities (up to 82% ee) for a broad range of ketimines.

氨基甲酸酯型有机催化剂的制备及应用

碳酸乙烯酯(EC)和四乙烯五胺(TEPA)通过加成反应制备了用于酯交换合成碳酸甲乙酯(EMC)的氨基甲酸酯型有机催化剂(TEPA-EC)。采用FTIR、NMR对其结构进行了表征,分析了其催化机理,考察了合成和使用条件对催化效率的影响,对TEPA-EC的稳定性和耐水性进行了测试。结果表明,TEPA-EC中的叔胺基甲酸羟乙酯基团通过协同氢键催化酯交换反应;EC与TEPA按物质的量比5∶1在140℃反应2 h制得的TEPA-EC具有较高的催化活性。对于n(DMC)∶n(EtOH)=2∶1在78℃反应7 h的酯交换反应,当EtOH 4.60 g、TEPA-EC用量为1%时(以原料总质量计,下同),EtOH的转化率为59.50%、EMC的选择性为83.77%,催化效率与工业化应用的乙醇钠相当;用量3%的TEPA-EC在8次重复使用和14次带水循环使用过程中,EtOH的转化率、EMC的选择性分别在62.35%、86.03%和57.33%、87.91%左右,优于乙醇钠的稳定性和耐水性。

有机催化剂在不对称合成中的应用

根据不同结构类型综述了近几年来各种有机催化剂的特点、机理及其在不对称合成中的应用研究进展.