手性噻唑烷-铑(I)配合物催化的苯乙酮不对称硅氢化反应

由L-半胱氨酸甲酯与α-吡啶甲醛缩合制备了2-(α-吡啶基)-4-羧甲基-1, 3-噻唑烷手性配体。用该手性配体与[Rh(COD)]2反应原位生成的Rh(I)配合物为催化剂进行了苯乙酮的不对称硅氢化反应。反应的化学产率达91%, 光学产率达82.1%e.e.。考察了各种反应条件对催化剂性能的影响。     

手性噻唑烷-铑(I)配合物催化的苯乙酮不对称硅氢化反应

由L-半胱氨酸甲酯与α-吡啶甲醛缩合制备了2-(α-吡啶基)-4-羧甲基-1, 3-噻唑烷手性配体。用该手性配体与[Rh(COD)]2反应原位生成的Rh(I)配合物为催化剂进行了苯乙酮的不对称硅氢化反应。反应的化学产率达91%, 光学产率达82.1%e.e.。考察了各种反应条件对催化剂性能的影响。     

磺化聚苯乙烯大孔树脂催化醛、酮与乙二醇缩合

合成了交换量不同的磺化聚苯乙烯大孔树脂,并将其运用于催化环已酮与乙二醇、苯甲醛与乙二醇的缩合反应。实验表明,磺化聚苯乙烯大孔树脂对醛、酮与乙二醇的缩合反应的催化效果良好,在0.2mol酮(或醛)中加入0.1g树脂,催化环己酮与乙二醇缩合反应的产率最高可达98.2%,催化苯甲醛与乙二醇缩合反应的产率可达73.3%。同时还发现磺化聚苯乙烯大孔树脂的交换量与催化合成缩酮、缩醛的产率有关,交换量为1.00mmol/g时其产率最高,催化性能较稳定。交换量小和交换量太大的树脂催化产率低。该树脂可以重复使用。催化反应完成后,树脂与反应液的分离十分方便,且催化剂对环境没有污染。     

阿魏酸甲酯的一锅法绿色合成

以香兰素、丙二酸二乙酯为主要原料,以甘氨酸为催化剂,无水甲醇为溶剂,经水解、酸化和Knoevenagel缩合等反应一锅式合成了阿魏酸甲酯。较适宜的反应条件为n(香兰素):n(丙二酸二乙酯):n(甘氨酸)=1.0:1:8:0.15、反应时间8 h、甲醇用量110ml,产率72.3%。     

磷钨酸铜绿色催化合成缩醛(酮)及其催化活性测定

合成了绿色杂多酸盐催化剂磷钨酸铜;将环己酮、苯甲醛同乙二醇、1,2-丙二醇的缩合反应作为探针反应,测定了催化剂的催化活性,比较系统地考察了催化剂用量、物料配比、反应时间、带水剂用量等因素对反应产率的影响.结果表明:在底物醛(酮)用量0.2 mol、醛(酮)/乙二醇(1,2-丙二醇)摩尔比1.0/1.5、催化剂用量0.5 g、带水剂环己烷用量18 mL、一定温度下回流反应2.0 h,1,4-二氧螺[4,5]癸烷产率为83.3%,3-甲基-1,4-二氧螺[4,5]癸烷产率为89.7%,2-苯基-1,3-二氧环戊烷产率为66.7%,4-甲基-2-苯基-1,3-二氧环戊烷产率为78.5%.     

钨过氧酸盐离子液体催化过氧化氢氧化苯甲醇制苯甲酸

用甲基三辛基氯化铵和钨酸钠一步法合成甲基三辛基季铵钨酸盐离子液体[(CH3)N(n-C8H17)3]2W2O11,以该离子液体为催化剂,在无反应溶剂条件下催化过氧化氢氧化苯甲醇生成苯甲酸。 考察了反应温度、催化剂用量以及氧化剂过氧化氢用量对苯甲酸产率的影响。 确定优化条件：反应温度70 ℃,苯甲醇用量5 mmol,催化剂用量是底物的0.4%(摩尔分数),30%过氧化氢用量2 mL,苯甲醇的转化率可达99%,苯甲酸选择性为98%。 该方法具有反应条件温和、产率高和选择性好的优点。     

无溶剂条件下氨基磺酸锂催化合成氧杂蒽化合物

在无溶剂条件下, 芳香醛与 5,5-二甲基-1,3-环己二酮或1,3-环己二酮经氨基磺酸锂催化缩合反应合成了氧杂蒽. 结果表明, 当催化剂用量为3%(摩尔分数)时, 在120 ℃反应 40~70 min, 产率高达 90% 以上. 此外, 探讨了该反应的氨基磺酸锂催化机理. 该合成方法具有操作简单, 反应时间短、 产率高及对环境友好等优点, 是现有氧杂蒽化合物合成方法的一个重要补充.     

无溶剂条件下活性炭固载硫酸催化酮和芳香醛的Cross-Aldol缩合反应

以活性炭固载硫酸(acsa)为催化剂,在无溶剂条件下催化酮和芳香醛的Cross-Aldol反应,成功合成了16个相应的α,β不饱和缩合产物,反应时间30～100min,产率可达65%～94%.该方法不仅反应时间短,产率高,催化剂可以重复利用,后处理简单,而且还对环境友好.产物经熔点,IR,1HNMR,13CNMR确证.     

活性炭负载壳聚糖催化室温无溶剂Knoevenagel缩合反应

通过活性炭(AC)负载壳聚糖(CS)的方法,制备了负载型的"壳聚糖/活性炭"催化剂(CS/AC)。利用FT-IR、XRD、TG-DTG、SEM、BET、元素分析等方法对催化剂进行表征,并系统研究了该催化剂在Knoevenagel缩合反应中的催化性能。结果表明,催化剂具有较好的活性,在室温无溶剂条件下,可以催化一系列芳香醛化合物与活泼亚甲基化合物进行缩合反应,产率均在80%以上;且反应体系放大100倍时,仍然保持较高的催化效率;此外,该催化剂具有较好稳定性,重复使用8次后,仍然保持较高的催化活性。     

NaHSO4·H2O催化合成苯甲酸甲酯

以NaHSO4*H2O催化苯甲酸与甲醇的酯化反应,合成了苯甲酸甲酯.研究结果表明,NaHSO4*H2O具有较高的催化活性.考察了苯甲酸/甲醇摩尔比、催化剂用量及反应时间对酯产率的影响.在优化反应条件[n(苯甲酸)∶n(甲醇)∶n(NaHSO4*H2O)=1∶2∶0.29,回流8h]下,苯甲酸甲酯产率达85.3%.     

新型功能离子液体水相催化芳醛与5,5-二甲基-1,3-环己二酮的反应

以N,N,N′,N′-四甲基乙二胺、1,3-丙磺酸内酯为原料,经酸化合成了功能化离子液体N,N,N′,N′-四甲基N,N′-二磺丙基二硫酸氢盐(TSIL)。 TSIL离子液体兼具Bronsted 酸性官能团和季铵盐相转移催化剂的结构,能够实现水相中芳醛与5,5-二甲基-1,3-环己二酮反应,得到氢化氧杂蒽衍生物。 结果表明,合成的TSIL具有较高的催化活性,在水相中于100 ℃下回流2～3 h即可完成反应,产率可达80%～93%。 反应生成的取代氢化氧杂蒽与离子液体的水溶液不相溶,通过简单的过滤可实现产物与催化体系的分离,简化了分离过程,方法操作简便、环境友好、催化剂可回收并重复使用。     

Perfluoroalkylated-pyridine catalyzed Aldol condensations of aldehydes and ketones in a fluorous biphasic system without fluorous solvent

Aldol condensation of different ketones with various aromatic aldehydes proceeds efficiently in the presence of catalytic amount of perfluoroalkylated-pyridine in a fluorous biphasic system without fluorous solvent, which has prompted various concerns involving cost, solvent leaching, and environmental persistence. The catalyst can be recovered by simple cooling and precipitation and used again.     

Microwave-assisted Knoevenagel condensation in aqueous over triazine-based microporous network

A high nitrogen-containing triazine-based microporous polymeric (TMP) network was used as an efficient metal-free catalyst for Knoevenagel condensation of ethylcyanoacetate with aromatic aldehydes. The reactions were performed in water as an environmentally benign medium, under microwave irradiation within a short reaction time of 10 min. The conversions of substituted aromatic aldehydes and selectivities for Knoevenagel products were found to be in the ranges of 44–99 and 65–99 %, respectively. The electron-withdrawing substituent showed higher conversion and selectivity as compared to electron-donating substituents. The TMP network can be readily recovered and reused up to three runs without loss in catalytic activity and selectivity.     

Boron trifluoride supported on nano-SiO2: an efficient and reusable heterogeneous catalyst for the synthesis of bis(indolyl)methanes and oxindole derivatives

Boron trifluoride supported on nano-SiO₂ was used as an efficient and heterogeneous catalyst for the electrophilic substitution reaction of indole with various aromatic aldehydes and isatins in methanol to afford the corresponding bis(indolyl)methanes and oxindole derivatives in high yields at room temperature and under reflux conditions, respectively. The catalyst can be reused several times without loss of its catalytic activity.     

((3-(3-硅胶丙基)硫基)丙基)硫酸酯作为可回收催化剂用于合成4,4'-芳亚甲基-双(1H-吡唑-5-醇)(英文)

Sulfuric acid ([3-(3-silicapropyl)sulfanyl]propyl)ester is employed as a recyclable catalyst for the condensation reaction between aromatic aldehydes and 3-methyl-l-phenyl-5-pyrazolone. This condensation reaction was performed in ethanol under refluxing conditions giving 4,4'-alkylmethylene-bis(3-methyl-5-pyrazolones) in 74-90% yields. The heterogeneous catalyst was recycled and used in eleven runs for the reaction between benzaldehyde and 3-methyl-l-phenyl-5-pyrazolone without losing catalytic activity.     

Selective synthesis of alpha,beta-unsaturated ketones by dibutyltin dimethoxide-catalyzed condensation of aldehydes with alkenyl trichloroacetates

Various alpha,beta-unsaturated ketones were stereoselectively synthesized in high yields up to 94% by a condensation reaction between alkenyl trichloroacetates and aldehydes using dibutyltin dimethoxide as a catalyst in the presence of methanol. This process is superior to the classical Claisen-Schmidt condensation with respect to mildness of the base catalyst and product selectivity.     

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…     

Nickel-Catalyzed α-Allylation of Aldehydes and Tandem Aldol Condensation/Allylation Reaction with Allylic Alcohols

An additive-free nickel-catalyzed α-allylation of aldehydes with allyl alcohol is reported. The reaction is promoted by 1 mol % of in situ formed nickel complex in methanol, and water is the sole by-product of the reaction. The experimental conditions allow the conversion of various α-branched aldehydes and α,β-unsaturated aldehydes as nucleophiles. The same catalyst and reaction conditions enabled a tandem aldol condensation of aldehyde/α-allylation reaction.     

Dibutyltin dimethoxide-catalyzed aldol reaction of enol trichloroacetates

A catalytic aldol condensation of aldehydes with enol trichloroacetates was achieved using dibutyltin dimethoxide as a novel catalyst in a mixed solvent consisting of THF and MeOH. Various β-hydroxy ketones were diastereoselectively obtained in high yields up to 99%.