Concise Synthesis of Chiral Tricyclic Lactams by Tandem Dynamic Kinetic Asymmetric Reductive Amination/Lactamization Using Ammonium Salts

The atom- and step-efficient synthesis of chiral fused tricyclic lactams from readily available ketoesters using cheap ammonium salts as the nitrogen source is reported. This ruthenium-catalyzed system operates through an efficient tandem dynamic kinetic asymmetric reductive amination (ARA)/lactamization and produces chiral fused tricyclic lactams in high yields with excellent diastereo- and enantioselectivity (up to >99 % ee, >20 : 1 dr and 98 % yield). The robust method was also applied to the concise synthesis of key intermediates in the synthesis of rivastigmine analogues and chiral N-heterocyclic carbene catalysts.     

手性相转移催化剂及其不对称催化反应

综述了手性季铵盐和手性冠醚两类手性相转移催化剂及其在不对称催化反应（包括加成，取代，氧化及还原等反应）中的应用，参考文献９７篇。     

Reductive Buchwald-Hartwig Amination of Nitroarenes with Aryl (pseudo)Halides

De novo catalytic syntheses of diarylamines from a palladium-catalyzed reductive Buchwald-Hartwig amination of nitroarenes with aryl (pseudo)halides is described. The exquisite use of upstream nitroarenes as arylamine surrogates, the judicious selection of bis(pinacolato)diboron (B₂pin₂) as a stoichiometric reducing agent, and wide substrate scope including (hetero)aryl halides (Cl, Br and I) and aryl triflates, constitute the striking features of the current protocol. Moreover, application of this technique to the syntheses of advanced intermediates and active pharmaceutical ingredients also proved successful, thus providing an alternative step-economical approach to the syntheses of diarylamine-incorporated molecules. Preliminary mechanistic investigation demonstrates that an amine and a nitrosoarene intermediates might be involved in this reductive event.     

手性金属络合物催化不对称Baeyer-Villiger反应

Baeyer-Villiger反应是有机化学基本反应之一,但是催化不对称Baeyer-Villiger反应的研究尚处于起步阶段。本文按手性配体的不同,评述了手性金属络合物催化不对称Baeyer-Villiger反应的研究,特别是由外消旋或前手性酮制备光学活性内酯的研究进展。     

A Strong-Acid-Resistant [Th6] Cluster-Based Framework for Effectively and Size-Selectively Catalyzing Reductive Amination of Aldehydes with N,N-Dimethylformamide

Utilization of N,N-dimethylformamide (DMF) as an amine source and reductant for synthesizing tertiary amines is a promising way to replace the substrates formaldehyde and dimethylamine, and it is desirable to seek porous acid-resistant catalysts for heterogeneous catalysis of this reaction. Herein, a robust metal–organic framework (MOF) {[Th₆O₄(OH)₄(H₂O)₆(BCP)₃]⋅10 DMF}_n ( 1 ) containing stacked nanocages with a diameter of 1.55 nm was constructed. Compound 1 can maintain its single-crystal structure even kept in air at 400 °C for 3 h, and in DMF or water at 200 °C for 7 days. Density functional theory (DFT) calculations suggested that the high interaction energy between the [Th₆O₄(OH)₄(H₂O)₆]¹²⁺ clusters and ligands was responsible for the excellent stability of 1 . Catalytic investigations revealed that 1 can effectively and size-selectively catalyze the reductive amination of aldehydes with DMF, and it can be reused at least five times without obvious loss in catalytic activity.     

Primary Amines by Transfer Hydrogenative Reductive Amination of Ketones by Using Cyclometalated IrIII Catalysts

Cyclometalated iridium complexes are found to be versatile catalysts for the direct reductive amination (DRA) of carbonyls to give primary amines under transfer‐hydrogenation conditions with ammonium formate as both the nitrogen and hydrogen source. These complexes are easy to synthesise and their ligands can be easily tuned. The activity and chemoselectivity of the catalyst towards primary amines is excellent, with a substrate to catalyst ratio (S/C) of 1000 being feasible. Both aromatic and aliphatic primary amines were obtained in high yields. Moreover, a first example of homogeneously catalysed transfer‐hydrogenative DRA has been realised for β‐keto ethers, leading to the corresponding β‐amino ethers. In addition, non‐natural α‐amino acids could also be obtained in excellent yields with this method.     

Enantioselective Synthesis of Chiral Amides by a Phosphoric Acid Catalyzed Asymmetric Wolff Rearrangement**

The enantioselective addition of potent nucleophiles to ketenes poses challenges due to competing background reactions and poor stereocontrol. Herein, we present a method for enantioselective phosphoric acid catalyzed amination of ketenes generated from α-aryl-α-diazoketones. Upon exposure to visible light, the diazoketones undergo Wolff rearrangement to generate ketenes. The phosphoric acid not only accelerates ketene capture by amines to form a single configuration of aminoenol intermediates but also promotes an enantioselective proton-transfer reaction of the intermediates to yield the products. Mechanistic studies elucidated the reaction pathway and explained how the catalyst expedited the transformation and controlled the enantioselectivity.     

(S)-2-吡咯烷基甲醇衍生物的合成及其催化二乙基锌和醛的不对称加成反应

以天然L-脯氨酸为原料, 经酯化、氨基保护、格氏反应和催化氢解等4步反应合成了光学活性的β-氨基醇. 将其作为催化剂用于二烷基锌和醛的不对称加成反应, 分别考察了催化剂结构、用量、溶剂、反应温度等因素. 结果表明, 当催化剂质量分数为5%, 甲苯作溶剂, 在-10 ℃下, 以(S)-N- 苄基-2-吡咯烷-α,α-二(α-萘基)甲醇(3)作催化剂时, 所得仲醇的对映体过量(e.e.)最高为82%, 产率高达到100%.     

非螯合型手性双膦/钌催化的不对称氢化反应

对RuCl₃和手性双膦(2S,5S)-2,5-双-(二苯膦)-1,4∶3,6-双脱水-2,5-双去氧-L-艾杜醇(BDPI)催化的不对称氢化反应进行了研究,反应的转化率为100%,光学收率受[双膦]/[RuCl₃]比值的影响较大.在α-乙酰胺基肉桂酸的催化氢化反应中,[双膦]/[RuCl₃]=2.0时e.e.值最大,为68%;对衣糠酸的催化氢化,[双膦]/[RuCl₃]=3时e.e.值最大,为92%.     

Chiral Phosphino‐ and (Phosphinooxy)‐Substituted N‐Heterocyclic Carbene Ligands and Their Application in Iridium‐Catalyzed Asymmetric Hydrogenation

Enantiomerically pure iridium complexes with phosphino‐ and (phosphinooxy)‐substituted N‐heterocyclic carbene (NHC) ligands were synthesized. Investigation of their electronic properties showed a similar trans influence of the phosphino (or phosphinooxy) and the NHC units. The complexes were tested in iridium‐catalyzed hydrogenation. While low conversions were observed with unfunctionalized olefins, the catalysts proved to be suitable for hydrogenation of the α,β‐unsaturated ester 20 , allylic alcohol 21 , and imine 22 . The enantioselectivities were, however, moderate.     

Novel Chiral PNNP-Ru Complexes:Synthesis and Application in Asymmetric Transfer Hydrogenation of Ketones

The efficient catalytic systems generated in situ from RuCl2(PPh3)3 and chiral ligands N,N-bis[2-(di-o- tolylphosphino)-benzyl]cyclohexane-1,2-diamine(2) were employed for asymmetric transfer hydrogenation of aromatic ketones, giving the corresponding optically active alcohols with high activities(up to 99% conversion) and excellent enantioselectivities(up to 96% e.e.) under mild conditions. The chiral ruthenium(Ⅱ) complex (R,R)-3 has been prepared and characterized by NMR and X-ray crystallography.     

Asymmetric Cyclopropanation Catalyzed by a Copper—（Schiff—base）Complex with Double Chiral Centers

The catalytic asymmetric cyclopropanation ofolefins with diazoacetate esters has been one of themost important methodologies for the formation ofchiral cyclopropane compounds[1,2 ] .The design andthe synthesis of an efficientcatalystare a challeng-ing task for organic chemists.The catalysts con-taining various metals and optically active ligandshave been employed for the reaction[3 ,4] . The cop-per- ( Schiff- base) complex was reported by Nazokiet al.[5] ,which exploited the area of catalyti…     

Direct Asymmetric Reductive Amination for the Synthesis of Chiral β‐Arylamines

The highly efficient and direct asymmetric reductive amination of arylacetones catalyzed by an iridium complex for the preparation of enantiomerically pure β‐arylamines is described. The monodentate phosphoramidite ligand exhibits superb reactivity (TONs of up to 20 000) and enantioselectivity (up to 99 % ee). Additives played important roles in this reductive coupling reaction.     

Direct Reductive Amination of Aldehydes and Ketones with 2,4-Ionene-Based Borohydride Exchange Resin as a Novel Polymer-Supported Reducing Agent

Direct reductive amination of aldehydes and ketones were accomplished efficiently using high-capacity, ionene-based, polymer-supported borohydride reagent in isopropyl alcohol at reflux under neutral conditions. The reagent is easily prepared by mixing aqueous solution of 2,4-ionene bromide with an alkaline solution of sodium borohydride at room temperature. The generality of reaction was established using both aliphatic and aromatic aldehydes, ketones, and amines.     

Chiral Frustrated Lewis Pair@Metal-Organic Framework as a New Platform for Heterogeneous Asymmetric Hydrogenation

Asymmetric hydrogenation, a seminal strategy for the synthesis of chiral molecules, remains largely unmet in terms of activation by non-metal sites of heterogeneous catalysts. Herein, as demonstrated by combined computational and experimental studies, we present a general strategy for integrating rationally designed molecular chiral frustrated Lewis pair (CFLP) with porous metal–organic framework (MOF) to construct the catalyst CFLP@MOF that can efficiently promote the asymmetric hydrogenation in a heterogeneous manner, which for the first time extends the concept of chiral frustrated Lewis pair from homogeneous system to heterogeneous catalysis. Significantly, the developed CFLP@MOF, inherits the merits of both homogeneous and heterogeneous catalysts, with high activity/enantio-selectivity and excellent recyclability/regenerability. Our work not only advances CFLP@MOF as a new platform for heterogeneous asymmetric hydrogenation, but also opens a new avenue for the design and preparation of advanced catalysts for asymmetric catalysis.     

Asymmetric Hydroformylation Using a Rhodium Catalyst Encapsulated in a Chiral Capsule

Supramolecular capsules can be used to change the activity and selectivity of a catalyst through the influence of the second coordination sphere, reminiscent of how enzymes control the selectivity of their processes. In enzymes, this approach is used to also control the enantioselectivity of reactions in which the active catalytic site is often not chiral but the second coordination sphere is. We are interested in the possibility to generate a chiral second coordination sphere around an otherwise achiral transition metal complex for asymmetric catalysis. In this paper we show that the ligand template approach can be used to generate a chiral second coordination sphere around a rhodium complex, which is used in asymmetric hydroformylation.     

一种均相催化、两相回收的手性配体的合成及其催化烯烃不对称双羟化反应

在金鸡纳生物碱衍生物配体存在下，四氧化锇催化的烯烃的不对称双羟化反应(AD)已广泛用于手性药物、精细化学品和天然产物的合成.AD反应也是合成抗癌药物紫杉醇C13-片段的实用方法之一．然而，由于配体和四氧化锇价格昂贵以及锇的毒性限制了AD反应的工业生产．近年来，在     

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．     

Reductive Amination of Aldehydes and Ketones in a Heterogeneous System in THF and under Solvent-Free Conditions Using Sodium Borohydride-Silica Phosphoric Acid

Summary. A chemoselective, fast, efficient, and high yielding method for the preparation of amines by reductive amination of aldehydes and ketones using sodium borohydride in the presence of silica phosphoric acid in THF and under solvent-free conditions at room temperature is described.