茚及其衍生物的催化不对称合成

茚及其衍生物广泛存在于自然界中,其中多官能团化的茚类化合物大多具有重要的生物活性,因而非常具有成为药物的先导化合物的潜力。特别是茚类化合物的不对称合成吸引了有机化学家们的广泛关注,最近有许多相应的合成方法研究被报道,包括外消旋体拆分、手性辅基及底物诱导的合成和手性催化合成等。本文总结了茚及其衍生物的催化不对称合成研究进展,重点介绍过渡金属及有机小分子不对称催化反应,并对该领域的研究前景进行了展望。     

Alkylation of carboxylic acid derivatives with dialkoxytitanacyclopropane reagents

Methods for the generation of dialkoxytitanacyclopropanes (dialkoxytitanium olefin complexes) are surveyed. Alkylation of carboxylic acid derivatives with these reagents giving rise to -titanio ketones and related species, which are spontaneously transformed into the corresponding cyclopropane compounds or react with external electrophiles, are considered.     

Catalytic Asymmetric Dearomatization Reactions

This Review summarizes the development of catalytic asymmetric dearomatization (CADA) reactions. The CADA reactions discussed herein include oxidative dearomatization reactions, dearomatization by Diels–Alder and related reactions, the alkylative dearomatization of electron‐rich arenes, transition‐metal‐catalyzed dearomatization reactions, cascade sequences involving asymmetric dearomatization as the key step, and nucleophilic dearomatization reactions of pyridinium derivatives. Asymmetric dearomatization reactions with chiral auxiliaries and catalytic asymmetric reactions of dearomatized substrates are also briefly introduced. This Review intends to provide a concept for catalytic asymmetric dearomatization.     

Synthesis and Catalytic Asymmetric Reaction of Chiral Pyridine Prolinol Derivatives

The enantioselective reduction of prochiral ketones with borane in the presence of a chiral ligand leading to enantiomerically pure secondary alcohols has received considerable attention in recent years. [1] Enantiomerically pure secondary alcohols are important intermediates for the synthesis of various other organic compounds such as halides, esters, ethers, ketones and amines. To the best of our knowledge, the use of pyridine prolinol derivatives in the reduction of ketones has not been reported so far. Thus, it should be of interest to investigate the catalytic a bility of such ligands. We have an ongoing project in the synthesis and application of chiral pyridine derivatives in chiral molecular recognition[2] and we want to evaluate the effect resulting from the introduction of a pyridinyl moiety onto the catalysts. We expect that the cooperation of pyridine unit and chiral prolinol unit in new ligands may result in unique properties for catalytic reaction.     

Asymmetric Copper-Catalyzed Carbomagnesiation of Cyclopropenes

The highly diastereo- and enantioselective formation of polysubstituted cyclopropanes was easily achieved through the asymmetric copper-catalyzed carbomagnesiation reaction of nonfunctionalized cyclopropene derivatives. The carbometalated species generated in situ readily undergo C−C and C−X bond-forming reactions with various electrophiles with complete retention of configuration.     

Organocatalytically Enantioselective Approach to Polysubstituted Tetrahydropyridines and Piperidines

A convenient and highly enantioselective method for assembly of functionalized 1,2,3,4,5‐pentasubstituted tetrahydropyridines and piperidines was developed. This method relies on preparing the required enantiopure cyclic semi‐acetals via an organocatalyzed Michael addition/cyclization cascade reaction of aldehydes and α‐keto‐α,β‐unsaturated esters, and subsequent reductive amination/condensation with primary amines.     

β-胺基丙烯酸酯衍生物的不对称催化氢化反应研究进展

综述了近年来β-胺基丙烯酸酯衍生物的不对称催化氢化反应的研究工作, 并讨论了影响氢化反应活性与对映选择性的各种因素.     

New Chiral Pyridine Prolinol Derivatives and Preliminary Study on Asymmetric Catalytic Reaction

Two new chiral pyridine prolinol derivatives have been synthesized from N-alkylation of (S)-α,α-diphenyl-2-pyrrolidinemethanol with 2-bromomethylpyridine and 2, 6-dibromo-methyl-pyridine. The catalytic asymmetric borane reduction of prochiral ketones and the asymmetric addition ofdiethylzinc to benzaldehyde were investigated.     

Preparation of Metal Ion-Planted Mesoporous Silica by Template Ion-Exchange Method and Its Catalytic Activity for Asymmetric Oxidation of Sulfide

For the preparation of metal ion-planted MCM-41 we have developed a template ion-exchange method, in which the template ions of as-synthesized MCM-41 are exchanged for the metal ions in aqueous media. The cations of Al, Ti, Cr, Mn, Zn, and Zr could be incorporated with high dispersion, while those of Fe, Co, Ni, Cu, Ga, Pd, and Pt formed small particles on the outside of the MCM-41 particles. Investigation on the time course of the template ion-exchange process suggested that the exchange proceeded first between the template ion and a proton and subsequently between the proton and a metal cation. Among the resulting metal ion-planted MCM-41s, Mn-MCM-41 showed excellent activity for the epoxidation of aromatic olefins. Trans-stilbene oxide was obtained in 93% yield from stilbene in MeCN–DMF solution at 328 K for 96 h. Ti-MCM-41 was the most suitable catalyst for the oxidation of sulfide with H₂O₂. It should be noted that the oxidation proceeded asymmetrically on Ti-MCM-41 in the presence of optically active tartaric acid in a CH₂Cl₂ solution. The chemical yield and optical yield of sulfoxide reached 54 and 30% ee, respectively.     

New Methods and Synthetic Applications of Asymmetric Nitrogen Transfer

Structure/reactivity relationships of N-alkoxycarbonyl- and N-carboxamidooxaziridines are explored, and conditions are discovered for the efficient amination of sulfides and primary amines. Reactions of these oxaziridines with alkenes are also examined, and lead to interesting new heteroatom transfer reaction products. Finally, the aminative rearrangement of 2-alkoxydihydropyrans leads to a useful stereocontrolled synthesis of pyrrolidines which can undergo synthetic manipulations to give [2.2.1]- and [3.2.1]-azabicycles.     

Substituted Tetraaza‐ and Hexaazahexacenes and their N,N′‐Dihydro Derivatives: Syntheses,Properties, and Structures

The palladium‐catalyzed coupling of a substituted o‐diaminoanthracene and a substituted o‐diaminophenazine to substituted 2,3‐dichloroquinoxalines furnishes 10 differently substituted N,N′‐dihydrotetraaza‐ or ‐hexaazahexacenes with the quinoxaline group of the azaacenes carrying fluorine, chlorine, or nitro groups. The N,N′‐dihydrotetraazahexacenes with hydrogen, chlorine, and fluorine subtituents are oxidized to azaacenes, whereas only the parent N,N′‐dihydrohexaazahexacenes, with hydrogen substituents, are oxidized by MnO₂. The resultant azaacenes are characterized by their optical and spectroscopic data. In addition, single‐crystal X‐ray structures have been obtained for the parent tetraazahexacenes and their difluoro‐substituted derivatives. The di‐ and tetrachloro derivatives of the N,N′‐dihydrohexaazahexacene have also been structurally characterized.     

Synthesis of Polysubstituted Pyrrolizidines from Proline Derivatives and Conjugated Nitroolefins

The stereochemistry of 1,3-dipolar cycloaddition of azomethine ylides derived from aromatic aldehydes and i-proline alkyl esters with several nitroolefins was investigated. Cyclic and acyclic nitroolefins add to the anti form of the ylide in a highly diastereoselective but poorly regioselective manner to give pyrrolizidine derivatives. In a few cases, the stereochemical results strongly support a stepwise mechanism.     

合成二茂钛衍生物的超分子界面催化反应研究

设计了一种超分子催化合成二茂钛衍生物的反应模型,并通过水溶性β-环糊精聚合物(WS-β-CDP)催化两相法合成二茂钛衍生物的反应得到了证实.利用荧光光谱和电子吸收光谱对反应过程进行了在线监测,发现WS-β-CDP可作为超分子微反应器,优先与配体可逆地形成超分子配合物,将配体激活,并在两相界面与二氯二茂钛发生反应,形成目标产物;之后,产物脱离空腔留在了有机相,而下一个配体则进入反应器继续反应.同时发现,体系中WS-β-CDP的存在对提高二茂钛物种的稳定性非常有利,并使其安全pH值提高至10.60.     

Catalytic Asymmetric Synthesis of Allylic Alcohols and Derivatives and their Applications in Organic Synthesis

Allylic alcohols represent an important and highly versatile class of chiral building blocks for organic synthesis. This Review summarizes the plethora of methods developed for the catalytic asymmetric synthesis of enantioenriched allylic alcohols. These include: dynamic kinetic resolution (DKR/DKAT), nucleophilic 1,2‐addition to carbonyl groups, allylic substitution, oxidation of C? H bonds, the addition of O nucleophiles to π systems, reduction of unsaturated carbonyl compounds, and an alternative route from enantioenriched propargylic alcohols. Furthermore, these catalytic asymmetric processes are exemplified by their applications in the syntheses of complex molecules such as natural products and potential therapeutic agents.     

Direct Amination of Naphthazarin,Juglone, and Some Derivatives

Mono‐ and diamino‐derivatives of naphthazarin, 2‐methoxynaphthazarin, juglone and their methylethers were prepared by reaction with ammonia. The structure of the products was established by NMR studies. Some compounds were tested for cytotoxic activity.     

多取代吡啶类化合物的合成及生物活性

多取代吡啶类化合物的合成及生物活性;多取代吡啶;合成;生物活性     

A Lacunary Polyoxovanadate Precursor and Transition-Metal-Sandwiched Derivatives for Catalytic Oxidation of Sulfides

A SeO₃-centered lacunary Keggin-type heteropolyoxovanadate (hetero-POV) K₆H₂[SeV₁₀O₂₈(SeO₃)₃] ⋅ 14 H₂O ( 1 ) was isolated by one-pot reaction of KVO₃ and SeO₂ under acidic conditions. X-ray studies revealed that it comprised a single {VO₅}-capped trivacant B-α-type Keggin ion [SeV₉O₃₃(VO)]¹⁴⁻ with its lacunary sites decorated by three {SeO₃} pyramids. Interestingly, this new basic hetero-POV building block was further used as a precursor to assemble with different transition-metal (TM) ions, yielding a series of TM-sandwiched POVs K₆H₈[(SeV₁₀O₂₈(SeO₃)₃)₂(M(H₂O)₄)] ⋅ 24 H₂O (M²⁺=Mn²⁺ ( 2 ), Co²⁺ ( 3 ), Zn²⁺ ( 4 )). All four compounds were characterized by single-crystal X-ray structure analysis, IR, X-ray photoelectron spectroscopy (XPS), EPR, and ⁵¹V NMR spectroscopy. Importantly, three TM-sandwiched derivatives exhibited effective catalytic activity for the heterogeneous oxidative desulfurization of sulfides at room temperature.     

Preparation and Catalytic Properties of Polymer Supported Dendritic Metal Complex

Polymer supported materials are extensively used as oxidizing agent, reducing agent catalysts, photosensitizers ion exchange resins and agriculturally and pharmacologically active agents1. The application of polymer metal complexes has been widely investigated2. The polymer supported complex undergoes swelling in a suitable solvent medium and provides enough surface area in carrying out electron transfer reactions, which clearly emphasizes the influence of a polymer network in heterogeneous catalysis.In the present, we have succeeded in the grafting of "dendrimer-like" hyperbranched polymer onto the surface of chloromethyl polystyrene reactions.All the catalysts show promising catalytic activities for the oxidation of iso-propylbenzene in the mild reaction condition, in each case, hypnone 1, 2-phenyl-2-propanol 2 were obtained as the major products