Crystalline Inclusion Compounds Derived from Derivatives of Mandelic Acid. Host Synthesis, Inclusion Formation, and X-Ray Structures of a Free Host Compound and of DMSO Inclusion Complexes in Both Racemic and Optically Resolved Forms

New chiral host compounds based on mandelic acid derivatives having methyl (6a, b and 8a, b) or bromo substituents (7a, b) attached to the phenyl ring of mandelic acid and involving additional aromatic groups were synthesized. The inclusion properties of both the racemic and the optically resolved host species are reported, including solvent co-crystallization as well as chiroselective and vapour sorptive inclusion. The structures of the free racemic host compound 6b and of the DMSO inclusion compounds of optically resolved and racemic 8 (8a and 8b, respectively) have been determined by X-ray analysis. Enantiomeric pairs of molecules in 6b form centro-symmetric dimers by mutual hydrogen bonding of one hydroxyl group while the other is involved in O-–H ... interactions. The guest molecules in the DMSO complexes of 8a and 8b are bound via hydrogen bonds to two host molecules related by translation along crystallographic axes. Parallels to previous hosts of this type are drawn.     

高效液相色谱法拆分雷喏嗪

用高效液相色谱法(HPLC)在正相条件下,用自制的涂敷直链淀粉-三(3,5-基苯基氨基甲酸酯)(ADMPC)手性固定相直接拆分了高效低毒的抗心绞痛药物雷喏嗪外消旋体(Ranolazine),并考察了二元及三元流动相体系对样品分离的影响,结果表明,三元流动相中的拆分结果远远好于二元流动相,流动相中不同种类醇改性剂及含量对样品保留时间和立体选择性有不同程度的影响．     

The first example of stereoselective self-assembly of a cryptand containing four asymmetric intracyclic phosphane groups

The rac stereoisomer of a novel cryptand containing two bridgehead nitrogen and four asymmetric phosphorus atoms in the 16-membered core cycle was obtained stereoselectively via the reaction of bis(mesitylphosphino)propane, formaldehyde, and meta-xylylenediamine in the course of a covalent self-assembly process.     

Louis Pasteur,Chemist: An Account of His Studies of Cinchona Alkaloids

Pasteur carried out pioneering work on cinchona alkaloids and their derivatives and his studies led to important discoveries. He examined crystals of cinchona alkaloids for his correlation of crystal hemihedrism with molecular chirality, studies that led Pasteur to the discovery of physicochemical differences between diastereoisomeric salts of tartaric acids with optically active cinchona bases, an important insight into fundamentals of molecular chirality. These physicochemical differences also led to Pasteur’s invention of the vital method of racemate resolution through diastereoisomeric derivatives. Pasteur clarified the confusion around the cinchona alkaloids by elucidating their identities and relations. He discovered the conversion of the major cinchona alkaloids to quinicine and cinchonicine, a finding subsequently of considerable importance in studies of the structure and synthesis of the major cinchona alkaloids. The reaction producing quinicine and cinchonicine led Pasteur to the discovery of the racemization of tartaric acid and the finding of meso‐tartaric acid, fundamental breakthroughs in the development of stereochemistry.     

(S)-(─)-α-苯乙胺萃取过程的研究

提出采用萃取法回收苯乙胺的工艺方案,考察了多种萃取剂的萃取性能,确定了氯仿作萃取剂的操作条件。根据实验和计算表明本方案苯乙胺的萃取收率可达９７％以上,苯乙胺的总回收率可达８７％以上。     

Occurrence and consequences of differences in the cation/anion ratios during classical resolution: D‐/L‐serine benzyl ester 2,3‐toluyl‐D‐tartrate

Differences in physical‐chemical properties of diaste‐reomeric salts allow the separation into the respective salts and subsequently into enantiomers by crystallization. Within this study unusual deviations in the cation‐/anion‐ratio of a diastereomeric salt pair were observed and characterized. While the n‐salt (L‐serine benzyl ester 2,3‐toluyl‐D‐tartrate) crystallizes in a ratio of two cations and one anion, the p‐salt (D‐serine benzyl ester 2,3‐toluyl‐D‐tartrate) consists of only one cation and one anion. Consequently the classical definition of a diastereomeric salt pair does not apply. In this contribution all differences in relevant thermodynamic properties of the unusual resulting diastereomeric salt pair are presented and discussed.     

Optically-active polyurethanes containing coumarin dimer component: Synthesis,characterization, and chiral recognition ability

Optically-active polyurethanes ( 2a-2c ) were prepared by polyaddition reaction of diamide ( 1a, 1b ) and diester ( 1c ) derivatives of chiral coumarin dimer with 4,4′-diphenylmethane diisocyanate (MDI) in chloroform and methyl ethyl ketone, respectively. The inherent viscosity of the polyurethanes are between 0.13 and 0.21 dL/g in N,N-dimethylacetamide (DMAc) at 30°C. Treated silica gels were absorbed with ca. 25 wt % of the polyurethanes, and packed as chiral stationary phases for direct optical resolution of 16 racemates with aromatic groups by high-performance liquid chromatography (HPLC). Polyurethanes 2a and 2b , obtained from diamide derivatives, show efficient resolution ability to some of the racemates (α = 1.06-1.79), especially the atropic ( R5 ) and trans ( R6-R9 ) isomers. The recognition ability of the polyurethanes can be attributed to the simultaneous aromatic stacking and hydrogen-bonding interactions with racemates. © 1992 John Wiley & Sons, Inc.     

THE IMMOBILIZATION OF AMINOACYLASE AND THE RESOLUTION OF D,L-PHENYLALANINE

A polymer with suitable physical characters and matched functional groups was synthesized,and used as a supporter to immobilize aminoacylase. The results showed that this supporterhad high immobilizing capacity and high selectivity for aminoacylase. Immobilized amino-acylase had high specific activity. In this paper, we determine the physical and chemicalcharacters of aminoacylase for resolution of D,L--phenylalanine, including its optimum tem-perature, pH, ion concentration, activated ion, substrate concentration, thermal stability anddenaturation. The immobilized aminoacylase was used to resolve the D,L-phenylalaninecontinuously. Thc resolved products was separated and purified with ion-exchange resins. L-phenylalanine solution was concentrated by vacuum evaporation and its hydrochloride wasformed. Checking of final product with polarimeter showed high yield and purity.     

Enantioselective and Synergistic Herbicidal Activities of Common Amino Acids Against Amaranthus tricolor and Echinochloa crus-galli

Amino acids have a wide range of biological activities, which usually rely on the stereoisomer presented. In this study, glycine and 21 common α-amino acids were investigated for their herbicidal property against Chinese amaranth (Amaranthus tricolor L.) and barnyard grass (Echinochloa crus-galli (L.) Beauv.). Both d- and l-isomers, as well as a racemic mixture, were tested and found that most compounds barely inhibited germination but moderately suppressed seedling growth. Various ratios of d:l-mixture were studied and synergy between enantiomers was found. For Chinese amaranth, the most toxic d:l-mixtures were at 3:7 (for glutamine), 8:2 (for methionine), and 5:5 (for tryptophan). For barnyard grass, rac-glutamine was more toxic than the pure forms; however, d-tryptophan exhibited greater activity than racemate and l-isomer, indicating the sign of enantioselective toxicity. The mode of action was unclear, but d-tryptophan caused bleaching of leaves, indicating pigment synthesis of the grass was inhibited. The results highlighted the enantioselective and synergistic toxicity of some amino acids, which relied upon plant species, chemical structures, and concentrations. Overall, our finding clarifies the effect of stereoisomers, and provides a chemical clue of amino acid herbicides, which may be useful in the development of herbicides from natural substances.     

以氧化锌为锌源的手性金属-有机骨架的合成及其用于联糠醛外消旋体的选择性吸附

通过使用氧化锌代替传统的金属无机盐为锌源,制备了手性金属-有机骨架（CMOF）[Zn（L-mal）（H₂O）₂]_n并对其手性分离性能进行了考察。将ZnO和L-苹果酸按物质的量之比1：1溶于水中,在室温下静置24 h即可得到[Zn（L-mal）（H₂O）₂]_n。以100 mg[Zn（L-mal）（H₂O）₂]_n为吸附剂,将250 μL 1 g/L的联糠醛外消旋体加入其中,并以4.5 mL异丙醇和1 mL甲醇为萃取剂和洗脱剂进行选择性吸附实验,最终滤液使用高效液相色谱仪（HPLC）进行分析。结果表明,[Zn（L-mal）（H₂O）₂]_n对R-联糠醛具有较好的选择性吸附,其对映体过量（ee）值为20%。该工作为CMOF的绿色制备提供了一定的方法和经验并拓展了其在手性分离领域的应用。