壳聚糖负载L-脯氨酸对水中不对称Aldol反应的催化性能

以壳聚糖为载体制备了负载型L-脯氨酸不对称催化剂;将合成产物用于催化丙酮与取代苯甲醛在水中的直接不对称Aldol反应,考察了其催化性能.结果表明,与在有机溶剂中的L-脯氨酸催化剂相比,在水相中的壳聚糖负载L-脯氨酸催化剂表现出更好的催化活性;就间硝基苯甲醛与丙酮在水中的不对称Aldol反应而言,壳聚糖负载L-脯氨酸催化下的产率和ee值分别达95%和48%.此外,壳聚糖负载L-脯氨酸催化剂在水中具有很好的重复使用性能,重复使用10次后相应的产率和ee值分别为88%和68%.     

高分子负载的羟基脯氨酸催化丙酮与邻-和对-硝基苯甲醛的不对称直接Aldol加成反应

以4(R)-羟基脯氨酸为原料，合成了高分子负载的脯氨酸衍生物，并用来催化丙酮对邻-和对-硝基苯甲醛的直接不对称Aldol加成反应，ee值最高可达80％，催化剂至少可以重复利用三次．     

离子对负载L-脯氨酸阴离子催化下的不对称Aldol反应

在水相中,通过阴阳离子结合使L-脯氨酸阴离子负载在基于Merrifield树脂的季铵根阳离子上,制备出功能性高分子离子液体.将该体系作为一种高效、可回收的催化剂用于催化醛与酮的不对称Aldol反应.结果表明:该催化体系在微量水中有很好的催化活性和立体选择性,相应的Aldol反应产物获得了6∶94的dr值以及高达98%的ee值,且该催化体系有较好的重复使用性能.     

固载脯氨酸类手性催化剂的制备及在不对称Aldol反应中的催化作用

制备了两种二氧化硅-甲基纤维素-脯氨酸类手性小分子复合催化剂,证明了它们可以在室温下催化不对称Aldol反应.所得产物产率较高,ee值最高能达到86.8%.这些催化剂比较稳定,并具有一定的重复使用的性能.     

L-脯氨酸催化的不对称Aldol缩合反应实验设计

介绍了L-脯氨酸催化的对硝基苯甲醛与丙酮的不对称Aldol反应的实验设计。室温反应2 h后，柱层析得到（R）-4-（4-硝基苯基）-4-羟基-2-丁酮，利用手性高效液相色谱测试得到产物的ee值。学生实验结果显示，收率范围为53%~74%，对映选择性范围为62%~69%。本实验方案将Aldol反应的研究成果设计成综合性实验，不仅强化训练了学生基本的实验技能和操作，同时拓宽了知识面，培养了学生分析问题、解决问题等方面的综合能力。     

氯甲基化聚苯乙烯负载修饰L-脯氨酸催化不对称Aldol反应研究

以氯甲基化聚苯乙烯为载体,分别以氨基胍、三聚氰胺和4,4′-二氨基苯磺酰苯胺(DASA)为连接臂,合成了三种负载修饰L-脯氨酸催化剂,并且将其用于催化不对称Aldol反应,探索了溶剂和底物对其催化性能的影响,并考察了其重复使用性能.结果表明,DASA负载修饰L-脯氨酸催化剂具有较好的催化活性和选择性,相应的最高产率达83%,e.e.值达86%.     

C2对称性有机小分子催化的高对映选择性Aldol反应

以环己酮与4-硝基苯甲醛直接不对称Aldol缩合为模型反应, 对一系列具有C2对称性的有机小分子催化剂进行了考察, 其中(2S,5S)-吡咯烷-2,5-二羧酸的不对称催化效果最好. 在10 ℃下, 以DMSO为溶剂, 30%摩尔分数催化剂用量, 研究了多个取代芳香醛和环己酮的不对称催化Aldol反应, 对映选择性为87%～99% ee.     

手性口恶唑硼烷酮催化不对称Aldol反应的研究

以廉价易得的手性氨基酸为原料合成了一系列氮磺酰化氨基酸配体,并将之与硼烷原闰制备成手性恶唑硼烷酮催化苯甲醛与烯醇硅醚的不对称Aldol反应,获得了较好的效果。对各种影响反应结果的因素进行了讨论,并对其不对称诱导机理进行了探讨。结果表明D-苯基甘氨酸衍生的手性恶唑硼烷酮催化剂对这种反应的催化效明显好于L-缬氨酸、L-亮氨酸、L-异亮氨酸等其它脂肪侧链氨基酸衍生的恶唑硼烷酮催化剂。其所得产物的化学产率和ee值分别为38.7%和81.7%。     

Merrifield树脂负载的L-脯氨酰L-苏氨酸二肽催化剂的合成及其对不对称Aldol反应的催化性能

制备了Merrifield树脂负载的L-脯氨酰L-苏氨酸二肽催化剂.将制备的催化剂用于催化直接不对称Aldol反应,并探索了溶剂、表面活性剂、催化剂用量、底物等不同条件对其催化性能的影响.结果表明,该催化剂在Tween-20水溶胶束中有很高的催化活性和较好的立体选择性,Aldol反应中部分产率达到85%以上,e.e.值达到78%,且该催化剂具有一定的重复使用性能.     

负载L-脯氨酸的温敏性共聚物的制备及其在水相中催化直接不对称Aldol反应

我们首先通过含N-boc保护手性单体与苯乙烯、N-异丙基丙烯酰胺(Nipamn)RAFT共聚,并进一步采取脱保护的方法制备一种负载L-脯氨酸的温敏性共聚物。该两亲性共聚物在水相中能够有效地催化直接不对称Aldol反应。此外,我们还研究了不同反应温度(0℃、25℃、35℃、50℃)对该催化剂的催化活性和立体选择性的影响,实验结果证明,该催化剂在其最低临界溶解温度(LCST)上下均有较高的催化活性和立体选择性,并且无论是其转化率还是ee值都能达到96%以上。     

A highly efficient organocatalyst for direct aldol reactions of ketones with aldehydes [corrected

L-proline amides derived from various chiral beta-amino alcohols that bear substituents with various electron natures at their stereogenic centers are prepared and evaluated for catalyzing the direct Aldol reaction of 4-nitrobenzaldehyde with acetone. Catalysts with strong electron-withdrawing groups are found to exhibit higher catalytic activity and enantioselectivity than their analogues with electron-donating groups. The presence of 2 mol % catalyst 4g significantly catalyzes the direct Aldol reactions of a wide range of aldehydes with acetone and butanone, to give the beta-hydroxy ketones with very high enantioselectivities ranging from 96% to >99% ee. High diastereoselectivity of 95/5 was observed for the anti Aldol product from the reaction of cyclohexanone, and excellent enantioselectivity of 93% ee was provided for anti Aldol product from the reaction of cyclopentanone.     

光响应负载型脯氨酸的合成及其在水相中催化不对称羟醛缩合反应的应用

应用RAFT聚合法合成了含脯氨酸、香豆素及聚乙二醇的光响应负载型催化剂(P),其结构经¹H NMR和元素分析表征。紫外光谱分析表明：在紫外光照前后, P的结构会发生变化。催化性能测试结果表明：P在紫外光照前后均能实现水相中催化环己酮和4-硝基苯甲醛之间的羟醛缩合反应,收率65%~76%, dr>93/7, ee>95%。     

负载脯氨酸及其衍生物催化的不对称C-C键形成反应研究进展

近年来脯氨酸及其衍生物催化的不对称有机反应受到了广泛关注,将其负载于载体上使用也引起了人们的极大兴趣.负载方式大致分为3种:共价键负载,离子对结合或物理吸附等作用负载,以及在离子液体中的两相催化剂.本文对近年来出现的负载脯氨酸及其衍生物催化的不对称反应(Aldol反应、Michael加成反应)研究进展进行了综述.     

Interaction between chicken protein tyrosine phosphatase 1 (CPTP1)-like rat protein phosphatase 1 (PTP1) and p60(v-src) in v-src-transformed Rat-1 fibroblasts

CPTP1 is a nontransmembrane chicken protein tyrosine phosphatase having 92% sequence homology to the corresponding 321 amino acids of human protein tyrosine phosphatase 1B (HPTP1B). Using anti-CPTP1 antibody, we identified CPTP1-like rat PTP1 of 51 kDa in Rat-1 and v-src-transformed Rat-1 fibroblasts. Here we show that CPTP1-like rat PTP1 binds to p60(v-src) in vivo and CPTP1 also can associate with p60(v-src) in cell lysate of v-src- transformed Rat-1 fibroblasts. Interaction between HPTP1B-type PTPs, CPTP1-like rat PTP1 and CPTP1, and p60(v-src) was reduced by vanadate treatment for 13 h due to down regulation of the protein level of p60(v-src) in vivo. Interestingly, CPTP1-like rat PTP1 was coimmunoprecipitated with a 70-kDa protein which has a possibility to be tyrosine- phosphorylated by p60(v-src) in v-src-transformed Rat-1 fibroblasts. These results suggest that HPTP1B-type PTPs may play an important role in p60(src) dependent signal pathway in eucaryotic cells.     

L-Proline Functionalized Polymers Prepared by RAFT Polymerization and Their Assemblies as Supported Organocatalysts

We have prepared a range of well-defined copolymers of styrene and L-proline functionalized styrene (5-11 kDa) using reversible addition-fragmentation chain transfer (RAFT) polymerization techniques and explored their use in supported catalysis. Upon deprotection of the L-proline functionalities, the solution self-assembly of these copolymers was investigated in mixed solvent systems. The resulting assemblies were characterized by dynamic light scattering, transmission electron microscopy (on graphene oxide substrates, along with cryo-TEM and tomography), and scanning electron microscopy. The application of these functional assemblies as supported catalysts for the aldol condensation reaction was explored using cyclohexanone and 4-nitrobenzaldehyde. The rate and selectivity of solution catalysis in our self-assembled system were comparable to those of L-proline, and a significant advantage of our system was that the polymer support could be utilized at lower catalyst loadings with comparable activity and also could be recycled a number of times while maintaining activity and selectivity.     

A biosensor for L-proline determination by use of immobilized microbial cells

A biosensor to quantify L-proline within 10(-5)-10(-3) mole/L concentration is described. Immobilized Pseudomonas sp. cells grown in a medium containing L-proline as the only source of carbon and nitrogen were used to create the biosensor. The cells oxidized L-proline specifically consuming O2 and did not react with other amino acids and sugars. The change in oxygen concentration was detected with a Clark oxygen membrane electrode. The cells were immobilized by entrapment in polyvinyl alcohol (PVA) cryogel. The resultant biocatalyst had a high mechanical strength and retained its L-proline-oxidizing ability for at least two months.     

A concept of supported amino acid ionic liquids and their application in metal scavenging and heterogeneous catalysis

Novel supported task-specific ionic liquids have been developed for the first time via the ionic-pair coupling of imidazolium cation of the modified polystyrene support with L-proline. The materials have shown an efficient metal scavenging ability (e.g., CuI, Pd(OAc)2, Pd0, and IrCl3) without the aid of a nonimmobilized ionic liquid, which relies on the highly synergistic effect of the coordination with the nitrogen atom and the COO- group of the L-proline moiety, electrostatic forces, and steric protection. The resulting metal-soaked supported ionic liquids can be used as efficient heterogeneous catalysts. These materials have been investigated in the CuI-catalyzed N-arylation of nitrogen-containing heterocycles and exhibit much higher catalytic activity and a more extensive structural range of aryl and heteroaryl halides than those exhibited by free L-proline in combination with CuI both in the ionic liquid ([BMIM][BF4]) and in the corresponding homogeneous reaction conditions. The CuI-soaked catalyst 4a-2 can be recycled for nine runs at least without any considerable loss of activity. To the best of our knowledge, our catalytic process is among the most efficient approaches to the N-arylation of imidazoles with aryl halides so far reported. Furthermore, the Pd-soaked material 4a-2 also shows higher catalytic activity in the solvent-free hydrogenation of styrene to ethylbenzene. This new concept is generally applicable and may easily be extended to other supported task-specific ionic liquids.     

二苯并-18-冠-6在交联聚乙烯醇微球表面的固载化

通过氯甲基化反应,将冠醚二苯并-18-冠-6(DBC)转变为氯甲基化的冠醚(CMDBC),使交联聚乙烯醇(CPVA)微球表面的羟基与CMDBC之间发生亲核取代反应,从而实现冠醚的固栽化,制得了固载有冠醚的功能微球DBC-CPVA.在建立了冠醚DBC固载量测定方法(溴百里香酚蓝-固相萃取法)的基础上,重点研究了主要因素对DBC固栽化过程的影响规律.结果表明:反应温度与溶剂性质对DBC在CPVA微球上的固载化反应有较大的影响,在70℃极性较强的N,N-二甲基甲酰胺(DMF)溶剂中,可制得冠醚DBC固载量为1.72 mmol/g的DBC-CPVA功能微球.