含氮手性及外消旋配体与铑络合物在苯乙酮不对称氢转移反应中的应用

将由手性配体(1S,2S)-N-对甲苯磺酰基-1,2-二苯基乙二胺与铑金属络合物二-μ-氯-二(1,5-环辛二烯)二铑;外消旋配体(±)-1,1'-联-2-萘胺、手性活化剂(1S,2S)-1,2-二苯基乙二胺与铑金属络合物二-μ-氯-二(1,5-环辛二烯)二铑组成的两种催化剂体系用于催化苯乙酮的不对称氢化反应.由气相色谱法及旋光测定法对反应物的转化率及产物的光学纯度分析的结果表明,手性配体和铑金属络合物组成的手性配体催化体系对苯乙酮的转化率为5.11%,产物的光学纯度为72.16%;而外消旋配体、手性活化剂与铑金属络合物组成的外消旋配体催化体系对苯乙酮的转化率为42.84%,产物的光学纯度为16.17%,由此说明手性配体催化体系较外消旋配体催化体系表现出更高的光学选择性.     

均相体系中含氮双齿膦配体对1-十二烯氢甲酰化反应的影响

含氮双齿膦配体(ph2PCH2)2NCH2CH2OCH2CH2NHCH2CH2PO3Na2(以A表示)在1-十二烯的氢甲酰化反应中的实验结果表明双膦配体的螯合作用降低了催化活性以及双膦-铑配合物有利于直链醛的生成.A与油溶性催化剂HRh(CO)(PPh3)3在合成气氛下发生配体交换形成配合物HRh(CO)(A)(PPh3),其催化活性比单膦-铑配合物的催化活性更低.由于双膦与铑配位后形成的络合物中铑的配位空间更拥挤,因此1-十二烯的端碳原子更容易与铑中心络合配位,形成直链烷基-铑络合物,使得产物醛中直链醛的含量增大.     

手性亚磷酸酯-膦配体的合成、与铑(Ⅰ)的配位性能及催化反应研究

合成了具有立体和电子不对称结构的手性亚磷酸酯-膦配体,使用31P NMR和红外吸收光谱考察了其与金属铑(Ⅰ)离子的配位性能,并研究了得到的配合物对烯烃氢甲酰化反应的催化性能。获得了好的催化活性和区域选择性,但反应的对映选择性很低。     

两相体系中含氮双齿膦配体对1-十二烯氢甲酰化反应的影响

含氮双齿膦配体(Ph2PCH2)2NCH2CH2OCH2CH2NHCH2CH2PO3Na2(以A表示)在1-十二烯的氢甲酰化反应中的实验结果表明双膦配体的螯合作用降低了催化活性和有利于直链醛的生成.A与水溶性催化剂RhCl(CO)(TPPTS)2在合成气氛下发生配体交换后,形成配合物HRh(CO)(A)(TPPTS),其催化活性比单膦-铑配合物的催化活性更低.又由于双膦与铑配位后形成的络合物中铑的配位空间更拥挤,因此1-十二烯的端碳原子更容易与铑中心络合配位,形成直链烷基-铑络合物,使得产物醛中直链醛的含量增大.     

新型水溶性手性钌催化剂的制备及应用

利用发烟硫酸磺化手性双胺双膦配体[（R．R）-C6P2（NH）2]．合成了PNNP-型水溶性手性双胺双膦配体[（R．R）-C6P2（NH）2（SO3Na）4]，并分别与简单的钌、铑络合物反应，制备水溶性手性钌络合物催化剂[（R，R）-C6P2（NH）2（SO3Na）4RuCl2]和铑络合物催化剂[（R，R）-C6P2（NH）2（SO3Na）4RhCl]．经元素分析、红外光谱和核磁共振等对手性配体及手性Ru络合物进行了结构表征．进而用这些水溶性的钌，铑络合物催化剂或水溶性手性配体与铱络合物[IrHCl2（COD）]2组成的混合催化体系研究了多种芳香酮的不对称转移氢化。结果表明．在以异丙醇作为氢源时．对芳香酮的不对称转移氢化都具有较好的催化活性．与铑，铱催化体系相比，水溶性手性钌络合物催化体系具有更高的活性和对映选择性．对于苯乙酮的氢化．其转化率和对映选择性分别达到91.6％和93．0％e．e．．此外，进一步考察了反应温度和KOH用量对水溶性手性钌络合物催化苯乙酮不对称转移氢化性能的影响，并将水溶性手性钌络合物催化体系应用于多种芳香酮的不对称转移氢化，获得了高的收率和对映选择性，分别可达92．0％和96．4％e．e．．研究结果表明，水溶性手性钌络合物[CR．R）-G6P2（NH）2（SO3Na）4RuCl2]是芳香酮不对称氢转移催化氢化的优良催化剂.     

手性亚磷酸酯一膦配体的合成、与铑（Ⅰ）的配位性能及催化反应研究

合成了具有立体和电子不对称结构的手性亚磷酸酯-膦配体，使用，^31P NMR和红外吸收光谱考察了其与金属铑（Ⅰ）离子的配位性能，并研究了得到的配合物对烯烃氢甲酰化反应的催化性能。获得了好的催化活性和区域选择性，但反应的对映选择性很低。     

新型含氮联苯基手性配体的合成

含有轴手性联芳基结构单元的含氮手性配体在不对称催化反应中具有广泛的应用.在各类手性配体中,不对称因素如手性轴、手性中心和手性面等对手性配体的手性诱导能力具有重要的调控作用.以轴手性联苯基作为支撑骨架,以含有手性中心的光学纯的α-氨基酸为手性源,合成了含有α-氨基酸残基和联苯基结构单元的具有光学活性的新型含氮手性配体.     

手性含氮四齿配体催化苯丙酮的不对称氢转移氢化

利用8-羟基喹啉与手性环己基二胺的反应，合成了对空气和水稳定的手性含氮四齿配体（R，R）-C5N4；进而分别与钌、铑或铱等金属络合物组合，现场生成催化体系，用于苯丙酮的不对称氢转移氢化反应；考察了碱添加量、配体用量和底物与催化剂用量摩尔比对反应性能的影响．结果表明，该配体与RhHCO（PPh3）3的混合体系效果较好，可得到68％ee的对映选择性．     

有机小分子催化不对称环氧化

光学活性的环氧化合物是有机合成的重要原料.不对称环氧化反应可以使潜手性的烯烃转化为带有手性碳的环氧化合物,这个反应在医药、农药、香料等合成上具有重要的意义.有机小分子催化烯烃的不对称环氧化是一种高效,绿色的光学活性环氧化合物的合成方法,目前该类反应主要是通过手性酮和手性亚胺盐来催化实现的.文章介绍了该类反应的催化机理,并概述了这两类有机小分子催化的不对称环氧化反应的研究进展.     

新颖手性胺基膦配体在烯胺不对称催化氢化反应中的应用

将新颖的手性胺基磷配体，6，6'－二甲氧基－2，2'－双（二苯胺基膦）－1，1'－连苯的铑铬合物应用于烯胺类化合物的不对称催化氢化反应中，发现这个铑络合物是一个有效的手性催化剂，各种手性胺产物的转化率为100％，光学选择性（ee）也达到了51％－43％。     

Hydroformylation of olefins catalyzed by chiral phosphite-Rh（I） complexes

A series of chiral phosphite ligands based on chiral binaphthol have been designed and synthesized. Their Rhodium(I) complexes were found to be efficient catalysts for the asymmetric hydroformylation of styrene and vinyl acetate and showed excellent catalytic activities and chemos-electivities as well as good regioselectivities (branched alde-hyde/linear aldehyde). The enantioselectivities up to 37.0% ee and 38.1% ee were achieved in the hydroformylation of styrene and vinyl acetate respectively. The chiral bidentate phosphite ligands provided better enantioselectivities, however lower regioselectivities than the chiral mono-dentate phosphite ligand.     

金属有机化合物在催化不对称合成中的应用

不对称合成是当前有机化学研究的热点和前沿。催化不对称合成是制备光学活性化合物的有效方法,金属有机化合物作为试剂或催化剂在这一领域得到了广泛的应用。本文简要综述了金属有机化合物在不对称合成中的应用与进展。     

Efficient Synthesis of Optically Active Alcohols

1 Introduction Optically active secondary alcohols are versatile building blocks for synthesis of unnatural biological active compounds and functional materials. Therefore, study on efficient synthesis of optically active alcohols is becoming an important subject in synthetic organic chemistry. Catalytic asymmetric reduction of carbonyl compounds is a practical method to create chiral alcohols. For the past decades, a large number of catalytic methods have been developed to achieve this goal. …     

Proline-catalysed Mannich reactions of acetaldehyde

Small organic molecules recently emerged as a third class of broadly useful asymmetric catalysts that direct reactions to yield predominantly one chiral product, complementing enzymes and metal complexes. For instance, the amino acid proline and its derivatives are useful for the catalytic activation of carbonyl compounds via nucleophilic enamine intermediates. Several important carbon-carbon bond-forming reactions, including the Mannich reaction, have been developed using this approach, all of which are useful for making chiral, biologically relevant compounds. Remarkably, despite attempts, the simplest of all nucleophiles, acetaldehyde, could not be used in this way. Here we show that acetaldehyde is a powerful nucleophile in asymmetric, proline-catalysed Mannich reactions with N-tert-butoxycarbonyl (N-Boc)-imines, yielding beta-amino aldehydes with extremely high enantioselectivities-desirable products as drug intermediates and in the synthesis of other biologically active molecules. Although acetaldehyde has been used as a nucleophile in reactions with biological catalysts such as aldolases and thiamine-dependent enzymes, and has also been employed indirectly, its use as an inexpensive and versatile two-carbon nucleophile in asymmetric, small-molecule catalysis will find many practical applications.     

Tagging major quantitative trait loci for sheath blight resistance in a rice variety, Jasmine 85

This study was conducted with a clonal F₂ population of rice from a cross between Jasmine 85, a resistant variety, and Lemont, a susceptible cultivar. The rice plants belonging to each F₂ clone were divided into two plots, which were put in two replicates, respectively. Clonal parents were tested as controls. The plants were inoculated by short toothpicks incubated with RH-9, a virulent isolate of the pathogenic fungus,Rhizoctonia solani, which causes rice sheath blight. The extreme resistant and susceptible clonal lines were selected for construction of resistant and susceptible DNA pools, respectively. A total of 94 polymorphic markers evenly distributed on 12 rice chromosomes were used for bulked segregant analysis, three positive ones were found polymorphic between the two DNA pools, and three major QTLs for sheath blight resistance, Rh-2, Rh-3 and Rh-7, were identified. The three major QTLs were located on chromosomes 2, 3 and 7, and could explain 14.4%, 26.1% and 22.2% of the phenotypic variation.     

钯催化不对称氢化反应和氢解反应

实现了α-酰氧基芳基酮的化学选择性和对映选择性氢化及氢解反应,分别得到重要的手性二醇单酯、简单酮和手性α-酰氧基芳基酮.手性产物经过衍生,可应用于多种具有生物活性的天然产物和药物的合成中.该催化反应的底物与催化剂比例(S/C)可高达5 000~6 000,证明了均相钯催化氢化具有工业应用前景.     

聚乙二醇增强Rh—6G水溶液发光能力的机制研究

从添加聚乙二醇后的Rh-6G激光染料溶液的宏观性质及聚乙二醇与Rh-6G分子的相互作用的微观结构两个方面,探讨聚乙二醇增强Rh-6G荧光发射的机制。     

Optically active alcohols: Resolution and synthesis from asymmetric reduction of prochiral ketones

The recent methods of resolution, enantiomeric excess determination and synthesis of optically active alcohols from asymmetric reduction of prochiral ketones are reviewed in the article with references. Important functions and applications of optically active alcohols in biological and chemical research area are described in an introduction part. The following part deals with resolution and enaniiomeric excess determination of racemic alcohols. The next part discusses asymmetric reduction of prochiral ketone and related compounds, which including: (a) Reduction by chirally modified aluminum and boron hydrides: (b) Catalytic reduction with chiral transition metal, complexes: (c) Enantioselective reduction by hydride transfer from carbon: (d) Biocatalytic reduction: (e) Asymmetric synthesis of chiral nonracemic alcohols with help of physical methods. A conclusion about optically active, alcohols from asymmetric reduction of ketones followes in the final part of article. Foundation item: Supported by the Fundation of High Education Ministry for the Scholars Back from Abroad Biography: HU Xian-ming (1950-), male, Associate Professor, Ph. D. (Univ of Groningen), email: xmhu@wh.edu.cn.     

磺化聚苯硫醚—铑配合物催化的氢甲酰化

光电子能谱对水溶性碘化聚苯硫醚—铑配合物催化剂的测定结果表明,其中铑的价态为Rh~1,以链节/金属摩尔比为5的该配合物为催化剂,在互不相溶的水/有机溶剂二相介质中对十一烯酸甲酯的氯甲酰化反应进行了初步研究,考察了不同的温度、压力、pH值等反应条件对氢甲酰化反应的影响,在P_(H3)为1～3MPa内,随着氢分压的增大,产物的转化率和正异构比都随之增加,水相最佳反应pH值为8。     

Asymmetric spiroacetalization catalysed by confined Brønsted acids

Acetals are molecular substructures that contain two oxygen-carbon single bonds at the same carbon atom, and are used in cells to construct carbohydrates and numerous other molecules. A distinctive subgroup are spiroacetals, acetals joining two rings, which occur in a broad range of biologically active compounds, including small insect pheromones and more complex macrocycles. Despite numerous methods for the catalytic asymmetric formation of other commonly occurring stereocentres, there are few approaches that exclusively target the chiral acetal centre and none for spiroacetals. Here we report the design and synthesis of confined Br?nsted acids based on a C(2)-symmetric imidodiphosphoric acid motif, enabling a catalytic enantioselective spiroacetalization reaction. These rationally constructed Br?nsted acids possess an extremely sterically demanding chiral microenvironment, with a single catalytically relevant and geometrically constrained bifunctional active site. Our catalyst design is expected to be of broad utility in catalytic asymmetric reactions involving small and structurally or functionally unbiased substrates.