Asymmetric transfer hydrogenation catalyzed by a novel planar chiral N‐heterocyclic carbene–rhodium(I) complex

A novel chelated ferrocene‐based planar chiral N‐heterocyclic carbene‐Rh(I) complex was synthesized by a simple method. It was applied to the asymmetric transfer hydrogenation of prochiral ketones. Enantioselectivities of up to 67% ee were observed. Copyright © 2009 John Wiley & Sons, Ltd.     

Hydrogenation of aldehydes catalyzed by kieselguhr‐supported carboxymethylcellulose‐nickel complex

A new kieselguhr‐supported carboxymethylcellulose‐nickel complex (Kie‐CMC‐Ni) has been prepared by a simple method, which has been found to catalyze the hydrogenation of benzaldehyde, valeraldehyde and isobutyraldehyde to the corresponding alcohols in high yield (100, 92 and 86% respectively). The catalyst could be reused without obvious loss of its catalytic activity. Copyright © 2004 John Wiley & Sons, Ltd.     

Oxidation of benzyl alcohol with dioxygen catalyzed by an inorganic polymer–platinum complex

An inorganic polymer–platinum complex, magnesiasupported polytitanzane–platinum complex (MgO Ti N Pt), was prepared and used to catalyze the oxygenation of benzyl alcohol. It was found that this kind of catalyst has great activity and stability in the reaction. The objective product (benzaldehyde) was obtained in 100% yield in 6 hr under a moderate reaction temperature and atmospheric oxygen pressure. This inorganic polymer complex was also very stable during the reaction.     

Asymmetric hydrogenation of ketones catalyzed by silica‐supported chitosan‐iron‐nickel complex

A new silica‐supported biopolymer‐metal complex, silica‐supported chitosan‐iron‐nickel complex was prepared by a very simple method. This complex catalyst can be used as a catalyst in the asymmetric hydrogenation of propiophenone to (R)‐(+)‐1‐phenyl‐1‐propanol and acetophenone to (R)‐(+)‐1‐phenyl ethanol in 91.7 and 77.7% optical yields, respectively, at 110°C and under 70 kg/cm² pressure. The catalyst could be reused several times without any remarkable change in the catalytic activity. Copyright © 2004 John Wiley & Sons, Ltd.     

Asymmetric transfer hydrogenation of ketones catalyzed by nickel complex with new PNO-type ligands

The new polydentate mixed-N,P,O chiral ligands have been synthesized by the condensation of bis（o-formylphenyl）- phenylphosphane and R-phenylglycinol in CHCl₃,and fully characterized by IR,NMR and EIMS spectra.These ligands were employed with a simple Ni complex Ni（PPh_s）₂Cl₂ in situ as catalytic systems for asymmetric transfer hydrogenation of ketones,and the corresponding optical alcohols were obtained with up to 84%ee under mild conditions.     

Catalytic behaviors of silica‐supported natural biopolymer–oxalic acid–Pt complexes in hydrogenation

Three kinds of natural biopolymers, gelatin, alginic acid and sodium carboxymethylcellulose (NaCMC), were reacted with oxalic acid in the presence of silica to yield complexes on the surface of silica, followed by reaction with H₂PtCl₆ 6H₂O to form Pt complexes, SiO₂–gelatin–(COOH)₂–Pt, SiO₂–alginic acid–(COOH)₂–Pt, and SiO₂–NaCMC–(COOH)₂–Pt, respectively. These complexes were able to catalyze the hydrogenation of 1‐heptene to give n‐heptane and that of nitrobenzene to give aniline at 25 °C and under 1 atm H₂ in 100% yields. Experimental data show that the catalysts were very stable and could be reused without any remarkable change in catalytic activity. Copyright © 2000 John Wiley & Sons, Ltd.     

手性二胺修饰的Ru-TPP/γ-Al2O3催化苄叉丙酮不对称加氢反应

在温和条件下制备了三苯基膦(TPP)作保护剂的负载钌催化剂Ru-TPP/γ-Al2O3,以(1S,2S)-1,2-二苯基乙二胺,(S)-1,1-二(对甲氧苯基)-2-异丙基乙二胺,(8S,9S)-9-氨基(9-脱氧)二氢辛可尼定和(1S,2S)-环己二胺为手性修饰剂,考察了Ru-TPP/γ-Al2O3在苄叉丙酮不对称加氢反应中的催化性能.结果表明,以(1S,2S)-1,2-二苯基乙二胺作为修饰剂时,催化剂具有较高的活性和选择性.在有K2CO3存在的异丙醇和水的混合溶液中,在氢气压力4MPa,40℃和8h的条件下,苄叉丙酮的转化率达到了99%,对羰基加氢的选择性大于98%,不饱和醇的光学纯度ee值为47%.     

Oxidation of methanol catalyzed by silica-supported polystannazane–copper complex

Silica-supported polystannazane–copper complex has been prepared and used as a catalyst for the oxidation of methanol. The results showed that the catalyst could catalyze the oxidation of methanol to formaldehyde at a high yield and selectivity at 30°C and under 1 atm mild conditions. The N/Cu mole ratio in the complex, temperature and the amount of NaOH additive had much influence on the catalytic activity. The complex was stable during the reaction and could be used repeatedly.     

Asymmetric transfer hydrogenation of aromatic ketones catalyzed by the iridium hydride complex under ambient conditions

The chiral Ir catalytic system generated in situ from iridium hydride complex and chiral diaminodiphosphine ligand was employed in asymmetric transfer hydrogenation of aromatic ketones to give the corresponding optically active alcohols, with up to 99% ee in high yield were obtained even when the substrate-to-catalyst molar ratio reached 10000:1.     

手性二胺修饰的镍配合物催化苯乙酮及其衍生物的不对称加氢反应

本文研究了由手性修饰剂(S,S)D-DPEN(DPEN:1,2一二苯基乙二胺)在反应条件下与NiCl2(PPh3)2原位生成的手性催化剂对苯乙酮及其衍生物不对称加氢反应的催化性能,考察了反应温度、反应压力、(S,S)-DPEN浓度等变化因素对催化活性和对映选择性的影响。结果表明,在15℃,氢气压力为8.0MPa,乙醇作溶剂时,苯乙酮加氢产物(R)-苯乙醇的对映选择性达到了77.2%e.e。     

Asymmetric hydrogenation of methyl 3,5-dioxohexanoate catalyzed by ru-binap complex: a short step asymmetric synthesis of dihydro-60methyl-2-H-pyran-2-one

Hydrogenation of methyl 3,5-dioxohexanoate 3 using Ru₂Cl₄((R) or (S)-binap)₂(NEt₃) as the catalyst gave dominantly anti 3,5-dihydroxyester 9, which was then converted into unsaturated lactone 4. The pathway of the hydrogenation reaction was also investigated.     

α‐Amino acid: an effective ligand for asymmetric catalysis of transfer hydrogenation of ketones

Ruthenium complexes, prepared by mixing the potassium salt of α‐amino acids and [RuCl₂(arene)]₂, acted as catalysts for the asymmetric transfer hydrogenation of ketones from 2‐propanol in the presence of KOH. For example, the transfer hydrogenation of acetophenone from 2‐propanol was catalyzed effectively by the ruthenium complex prepared from potassium L ‐prolinate and [RuCl₂(p‐cymene)]₂ to give (R)‐1‐phenylethanol in 72% yield with 81% ee. The yields and enantioselectivities of the product were influenced strongly by the structure of the α‐amino acidate ligand, arene ligand, and substrate, by the amount of additional base, and by the concentration of the substrates. The best enantiomeric excesses of the products was 92%, when 1‐tetralone was subjected to this reaction using a prolinated ruthenium complex bearing p‐cymene. Furthermore, the potassium salts of dipeptides were tested as a ligand for this transfer hydrogenation. Copyright © 2001 John Wiley & Sons, Ltd.     

浸渍溶剂对Pt/炭-氧化铝催化氢化2-氧-4-苯基丁酸乙酯的影响

螯合辅助溶剂挥发共组装法制备的炭-氧化铝复合材料为载体,分别使用水、乙醇或二者混合物为氯铂酸的分散介质,浸渍制备炭-氧化铝复合材料负载Pt催化剂.通过XRD,N2物理吸附以及TEM表征可知,乙醇作为浸渍溶剂时,最有利于Pt的分散,而混合溶剂浸渍制备的催化剂Pt颗粒最大.2-氧-4-苯基丁酸乙酯不对称加氢反应结果表明,氯铂酸水溶液浸渍得到的催化剂Pt纳米粒子的粒径有利于获得高的光学选择性,催化剂经辛可尼丁修饰后,以乙酸为反应溶剂,可获得最高84.8%的光学选择性.此外,该催化剂重复利用性能优异,可以重复利用22次,活性没有下降.     

手性胺醇稀土配合物的合成、荧光性质及其催化芳香酮的不对称氢化反应

合成了三种新的含C₂-对称轴的手性胺醇(PhOHCHCH₂)₂NCH₂C₆H₄R (R＝OCH₃, L₁; R＝CH₃, L₂; R＝Cl, L₃), 将其与无水氯化稀土LnCl₃•4THF (Ln＝La, Sm, Gd)反应生成了九个新的胺醇类稀土配合物LLnCl•2THF (L＝L₁, L₂, L₃; Ln＝La, Sm, Gd). 用元素分析、热重分析、红外和紫外光谱等手段对它们进行了表征. 荧光光谱显示一些配合物具有荧光性能. 原位催化芳香酮的不对称氢化反应表明: L₁/SmCl₃•4THF体系催化苯乙酮不对称氢化反应的转化率达71%, 相应的对映体过量值达32%.     

金属催化的不对称氢化反应研究进展与展望

手性过渡金属络合物催化的不对称氢化反应是合成光学活性化合物的重要方法. 本文从手性配体及手性催化剂、不对称催化新反应、新方法和新策略三个方面简要评述新世纪以来过渡金属催化的不对称氢化反应研究领域的新进展. 从新世纪初至今, 手性单磷配体得到了复兴, 出现了如MonoPhos、SiPhos、DpenPhos等高效单齿亚磷酰胺酯配体; 磷原子手性(P-手性)配体也得到了快速发展, 如BenzP*、ZhanPhos、TriFer等已成为新的高效手性双膦配体; 螺环骨架手性配体成为新世纪手性配体设计合成的亮点, 除了SiPhos、SIPHOX、SpinPHOX等高效手性螺环配体外, 手性螺环吡啶胺基磷配体SpiroPAP的铱催化剂成为目前最高效的分子催化剂. 不对称催化氢化新反应研究也取得了突破, 如非保护烯胺、杂芳环化合物及N-H亚胺的氢化等反应都实现了高对映选择性. 自组装手性催化剂、树枝状手性催化剂、铁磁性纳米负载的可回收手性催化剂, 以及“混合”配体手性催化剂等新方法和新策略也在不对称催化氢化反应中得到了应用. 然而, 手性过渡金属络合物催化的不对称氢化研究仍然充满挑战, 也期待新的突破.     

氮氧双功能salen催化剂在酮的不对称硅氰化反应中的应用

通过在催化剂的不同位置同时引入LALB（Lewis acid/Lewis base）双功能基团（包括氮氧偶极基团和金属钛中心）来改善其催化活性和立体控制能力,合成基于salen骨架结构的新型氮氧双功能催化剂.在相对温和的条件下成功的将该类双功能催化剂应用于酮的不对称硅氰化反应,表现出了中等程度的选择性和非常高的反应活性...     

Asymmetric transfer hydrogenation of ketones using Ru(0) nanoparticles modified by Chiral Thiones

The catalytic asymmetric transfer hydrogenation (ATH) of acetophenone in isopropanol by Ru(0) nanoparticles (NPs) obtained by the in‐situ reduction of Ru (II) half‐sandwich complexes of chiral 2‐oxazolidinethiones and 2‐thiozolidinethiones was examined and compared with the catalytic activity of Ru(0) NPs formed in‐situ by the reduction of [Ru(p‐cymene)(Cl)₂]₂ in presence of optically active ligands such as (S)‐4‐isobutylthiazolidine‐2‐thione, (S)‐4‐Isopropyl‐2(?2‐pyridinyl)‐2‐oxazoline, (8S, 9R)‐(?)‐cinchonidine, (S)‐leucinol, (S)‐phenylalaninol, and (S)‐leucine. Three of the best catalytic systems were then examined for ATH of thirteen aromatic ketones with different electronic and steric properties. A maximum of 24% ee was obtained using NPs generated from the Ru (II) half‐sandwich complex with (S)‐4‐isobutylthiazolidine‐2‐thione in the TH of acetophenone. The NPs were characterized by TEM and DLS measurements. Kinetic studies and poisoning experiments confirmed that the reaction is catalyzed by the chiral NPs formed in‐situ. Complete characterization of the complexes, including the X‐ray crystallographic characterization of two complexes, was also carried out.     

钯或镍催化的有机镁及有机锌的不对称交叉偶联反应

综述了钯或镍的手性配合物催化的有机金属试剂与芳基及烯基卤化物的不对称交叉偶联反应,着重介绍了手性配体的发展及其对反应产物ee值的影响。对一些已研究得较清楚的反应的可能立体识别机理也作了介绍。