固相β-环糊精包结物诱导7-羟基-2-甲氧基-2-甲基色满的不对称合成

研究了室温下间苯二酚和甲基乙烯基酮分别与β-环糊精（ β-CD）形成包结物后的几种不同固相反应,结果表明包结物A（间苯二酚/β-CD）与包结物B（甲基乙烯基酮/β-CD）反应能够很好地得到目的产物,产率及ee值分别为82.8%和78.4%;间苯二酚与包结物B反应仅得到低光学活性产物（ee值为19.5%）;包结物A与甲基乙烯基酮反应却没有得到手性目的产物。以熔点、X-粉末衍射、固相核磁碳谱及ROESY多种方法对所形成的包结物进行了表征,包结物中主客体的比例（1：1）通过¹H NMR (400 MHz)得以确定,文章对固相环加成反应的机制也进行了初步探讨。     

Structural Studies for Specific Binding Capacity of β‐Cyclodextrin with Ibuprofen

Ibuprofen (Ibu) and β‐cyclodextrin (βCD) and its derivative (hydroxypropyl‐β‐cyclodextrin, HPβCD) complexes spatial geometry information were studyed. Firstly, phase solubility experiment was carried out for S‐(+)‐ibuprofen (SIbu) and cyclodextrins complex. The apparent stability constant (Kc) for 1:1 complexes are 1065 M‐1 (βCD) and 1476 M‐1 (HPβCD) respectively. Secondly, ¹H NMR and two‐dimensional rotating‐frame overhauser effect spectroscopy (2D ROESY) were used for binding study, and confirmed that benzene ring of Ibu is deeply included into the cavity and racemic Ibu (RSIbu) can be discriminated by βCD or HPβCD. Finally, docking model was given by theoretical investigation. The model with ‐4.77 kcal/mol binding energy matches experimental structure.     

Novel Anti‐Microbial Host‐Guest Complexes Based on Cationic β‐Cyclodextrin Polymers and Triclosan/Butylparaben

The preparation of novel cationic β‐cyclodextrin polymers (CPβCDs) and its complexes with butylparaben and triclosan were reported in this paper. FT‐IR and two‐dimensional (2D) ¹H–¹H gradient correlated spectroscopy (gCOSY) NMR spectra confirmed that the antibiotics could be included inside the lipophilic cavities of CPβCDs. The water solubility of the antibiotics was improved significantly after inclusion with CPβCDs. The results also suggest that it was easier for butylparaben, which had relatively small molecular size, to form the complexes with CPβCDs than triclosan. Due to the targeting effect after the inclusion with cationic CPβCDs, the anti‐microbial activity of butylparaben was also enhanced substantially. However, similar improvement was not obvious for triclosan.

     

Synthesis of New Carnosine Derivatives of β‐Cyclodextrin and Their Hydroxyl Radical Scavenger Ability

Several in vitro and in vivo studies have suggested that carnosine can act as a scavenger of reactive oxygen species and intracellular proton buffer. On the other hand, carnosinase is a specific peptidase able to destroy the biological active dipeptide. To overcome this constraint, β‐cyclodextrin (β‐CD) was functionalized with carnosine to give the following new compounds: 6^A‐[(3‐{[(1S)‐1‐carboxy‐2‐(1H‐imidazol‐4‐yl)ethyl]amino}‐3‐oxopropyl)amino]‐6^A‐deoxy‐β‐cyclodextrin ( 1 ), 6^A‐[(β‐alanyl‐L ‐histidyl)amino]‐β‐cyclodextrin ( 2 ), and (2^AS,3^AR)‐3^A‐[(3‐{[(1S)‐1‐carboxy‐2‐(1H‐imidazol‐4‐yl)ethyl]amino}‐3‐oxopropyl)amino]‐3^A‐deoxy‐β‐cyclodextrin ( 3 ). Pulse‐radiolysis investigation showed that the β‐CD derivatives 1 – 3 are excellent scavengers of OH^. radicals. Their activity is not only due to the formation of the stable imidazole‐centered radical, but also to the scavenger ability of the glucose moieties of the macrocycle (Scheme). This effect is independent of the disposition of the imidazole ring. In fact, the quenching constant values are similar for the three compounds.     

Crystal Structures of β‐Cyclodextrin Inclusion Complexes with 7‐Hydroxycoumarin and 4‐Hydroxycoumarin and Substituent Effects on Inclusion Geometry

Two inclusion complexes of β‐cyclodextrin‐7‐hydroxycoumarin ( 1 ) and β‐cyclodextrin‐4‐hydroxycoumarin ( 2 ) were prepared and their crystal structures were investigated by single crystal X‐ray crystallography under cryogenic condition. Both structures consist of stacks of face‐to‐face cyclodextrin dimers arranged in brickwork‐like pattern along the crystallographic a‐axis. For complex 1 , each of the two dimeric β‐cyclodextrins includes one 7‐hydroxycoumarin molecule that penetrates deeply into the cyclodextrin dimer and locates its lactonering at the center of the dimer cavity. For complex 2 , each cyclodextrin dimer accommodates three 4‐hydroxycoumarin molecules. One of them is sandwiched between two units of the cyclodextrin dimer, the other two are shallowly included in the cavities of the dimeric cyclodextrins respectively and protrude their lactone rings from the primary end of the cyclodextrin. The substituent effects of guest molecules on inclusion geometry of various coumarin molecules in β‐cyclodextrin were examined.     

IrIII and RuII Complexes Containing Triazole‐Pyridine Ligands: Luminescence Enhancement upon Substitution with β‐Cyclodextrin

Novel 2‐(1‐substituted‐1H‐1,2,3‐triazol‐4‐yl)pyridine (pytl) ligands have been prepared by “click chemistry” and used in the preparation of heteroleptic complexes of Ru and Ir with bipyridine (bpy) and phenylpyridine (ppy) ligands, respectively, resulting in [Ru(bpy)₂(pytl‐R)]Cl₂ and [Ir(ppy)₂(pytl‐R)]Cl (R=methyl, adamantane (ada), β‐cyclodextrin (βCD)). The two diastereoisomers of the Ir complex with the appended β‐cyclodextrin, [Ir(ppy)₂(pytl‐βCD)]Cl, were separated. The [Ru(bpy)₂(pytl‐R)]Cl₂ (R=Me, ada or βCD) complexes have lower lifetimes and quantum yields than other polypyridine complexes. In contrast, the cyclometalated Ir complexes display rather long lifetimes and very high emission quantum yields. The emission quantum yield and lifetime (Φ=0.23, τ=1000 ns) of [Ir(ppy)₂(pytl‐ada)]Cl are surprisingly enhanced in [Ir(ppy)₂(pytl‐βCD)]Cl (Φ=0.54, τ=2800 ns). This behavior is unprecedented for a metal complex and is most likely due to its increased rigidity and protection from water molecules as well as from dioxygen quenching, because of the hydrophobic cavity of the βCD covalently attached to pytl. The emissive excited state is localized on these cyclometalating ligands, as underlined by the shift to the blue (450 nm) upon substitution with two electron‐withdrawing fluorine substituents on the phenyl unit. The significant differences between the quantum yields of the two separate diastereoisomers of [Ir(ppy)₂(pytl‐βCD)]Cl (0.49 vs. 0.70) are attributed to different interactions of the chiral cyclodextrin substituent with the Δ and Λ isomers of the metal complex.     

β‐Cyclodextrin Pseudopolyrotaxanes with π‐Conjugated Polymer Axles

Summary: β‐Cyclodextrin (β‐CD) pseudopolyrotaxanes containing poly(thiophene‐2,5‐diyl), PTh , or poly(3‐methylthiophene‐2,5‐diyl)s, P3MeTh s, as an axle were prepared. Structures of the pseudopolyrotaxanes and their inclusion behavior with β‐CD were investigated. The UV‐vis measurements revealed that inclusion of P3MeTh s by β‐CD depended on the flexibility of the main chain and their molecular weight.

Formation of the inclusion complex of β‐CD and PTh .     

Synthesis and Characterization of β—Cyclodextrin Bonded Metal Porphyrins

Reactions of 5-(p-aminophenyl)-10,15,20-triphenyl porphyrin (1) with Ru3(CO)12 or M(OCOCH3)2 (M=Ni,Mn) afforded metalloporphyrins(4-6),respectively.6-Deoxy-6-io-do-β-cyclodextrin(2) and mono(6-O-trifluoromethanesulfonyl) permethylated β-cyclodextrin(3) reacted with complexes 4-6 to give β-cyclodextrin bonded metal porphyrins (7-9) and permethylated β-cyclodextrin bonded me-tal porphyrins (10-12) respectively.These new complexes were identified by MS,IR,UV-visible and ^1H NMR spectra,and elemental analysis.     

Interaction of β‐Cyclodextrin with Cetyltrimethylammonium Bromide in the Presence of Neutral Red and Its Application to the Spectrophotometric Determination of β‐Cyclodextrin

The effects of addition of β‐cyclodextrin (β‐CD) to the neutral red‐cetyltrimethylammonium bromide (CTAB) associates in pH 7 phosphate buffer solutions were investigated. Addition of β‐CD to neutral red‐CTAB association causes decomposition of the associate by displacement of neutral red with β‐CD. The inclusion complex of CTAB with β‐CD is more stable than that with neutral red. The results indicate that formation of inclusion complex of CTAB with β‐CD prevents its association with neutral red, and inclusion complex formation of β‐CD and neutral red in the presence of CTAB takes place after total consumption of CTAB. The competition of β‐CD and neutral red on the interaction with CTAB can be used for the simple, rapid and sensitive spectrophotometric determination of β‐CD.     

β-环糊精与有机胺之间包合作用的理论与实验研究

通过实验和理论计算方法研究了β-环糊精(CD)与乙二胺1及它的三个类似物: 二乙烯三胺2、三乙胺3和乙二胺四乙酸4之间的包合作用. 利用旋光法确定了β-CD与客体分子形成1:1型主–客体包合物, 在298.2 K下测定了包合物在水中的稳定常数(K). 采用半经验PM3方法考察了β-CD与短链脂肪胺1~7、环状脂肪胺8~11以及芳香胺12~13的分子间结合能力, 报道了β-CD与这些客体分子间的包合络合过程并讨论了这些包合体系之间的包合差异性. 变形能和水合能对包合体系的相互作用能的贡献均相当小. β-CD包合物的稳定性取决于主、客体分子之间的尺寸匹配. 对于β-CD与客体1~4形成的包合物而言, 旋光法测定的包合物的K值的顺序与PM3计算得到的包合物络合能绝对值的排序有很好的一致性.     

Synthesis of β‐Arylacyl/β‐Heteroarylacyl‐β‐alkylidene Malonates and Their Application in Substituted Pyridone Synthesis

A novel approach has been developed for the synthesis of β‐arylacyl/β‐heteroarylacyl‐β‐alkylidine malonates in moderate to good yields by the reaction of Stork aryl and heteroaryl enamine with β‐chloroalkylidene malonates. The reaction involves conjugate (Michael) addition of Stork enamine on β‐chloroalkylidene malonates and elimination of chloride ion. These Michael adducts were utilized as intermediates for the synthesis of highly substituted 1,4‐dialkyl‐2‐oxo‐6‐aryl/hetreoaryl‐1,2‐dihydro‐pyridine‐3‐carboxylic acid ethyl esters via 5 + 1 ring annulation protocol.     

Neutral and Cationic β‐Ketoiminato Bismuth Complexes

The first examples of neutral and cationic bismuth complexes bearing β‐ketoiminato ligands were isolated by employing salt metathesis route. BiCl₃ reacts with [O=C(Me)]CH[C(Me)N(K)Ar] ( 1 ) resulting in a homoleptic β‐ketoiminato bismuth complex Bi[{O=C(Me)}CH{C(Me)NAr}]₃ ( 2 ). The reaction between BiCl₃ and [(CH₂)₂{N(K)C(Me)CHC(Me)=O}₂] ( 3 ) leads to the formation of a cationic bismuth complex [Bi{(CH₂)₂(NC(Me)CHC(Me)=O)₂}]₄[Bi₂Cl₁₀] ( 4 ).     

Synthesis of Furanyl β‐Diketone‐based Heteroleptic Iridium(III) Complexes and Studies of Their Photo‐Luminescence Properties

Four iridium complexes containing furan moieties were synthesized and characterized. The positioning of the furan unit had a strong effect on the optical properties of the complexes. The synthetic methodologies developed pave the way for the introduction of oligofuran compounds in Ir^III heteroleptic complexes for OLED applications.     

Preparation of Protected β2‐ and β3‐Homocysteine, β2‐ and β3‐Homohistidine,and β2‐Homoserine for Solid‐Phase Syntheses

The Ser, Cys, and His side chains play decisive roles in the syntheses, structures, and functions of proteins and enzymes. For our structural and biomedical investigations of β‐peptides consisting of amino acids with proteinogenic side chains, we needed to have reliable preparative access to the title compounds. The two β³‐homoamino acid derivatives were obtained by Arndt–Eistert methodology from Boc‐His(Ts)‐OH and Fmoc‐Cys(PMB)‐OH (Schemes 2–4), with the side‐chain functional groups' reactivities requiring special precautions. The β²‐homoamino acids were prepared with the help of the chiral oxazolidinone auxiliary DIOZ by diastereoselective aldol additions of suitable Ti‐enolates to formaldehyde (generated in situ from trioxane) and subsequent functional‐group manipulations. These include OH→O^tBu etherification (for β²hSer; Schemes 5 and 6), OH→STrt replacement (for β²hCys; Scheme 7), and CH₂OH→CH₂N₃→CH₂NH₂ transformations (for β²hHis; Schemes 9–11). Including protection/deprotection/re‐protection reactions, it takes up to ten steps to obtain the enantiomerically pure target compounds from commercial precursors. Unsuccessful approaches, pitfalls, and optimization procedures are also discussed. The final products and the intermediate compounds are fully characterized by retention times (t_R), melting points, optical rotations, HPLC on chiral columns, IR, ¹H‐ and ¹³C‐NMR spectroscopy, mass spectrometry, elemental analyses, and (in some cases) by X‐ray crystal‐structure analysis.