旋光性高分子的合成（下）

旋光性高分子的合成（下）刘引烽，华家栋（上海科技大学化学系，上海，２０１８００）４不对称聚合由外消旋手性单体制备旋光性高分子必须通过选择性聚合才能实现。选择性聚合是指外消旋的两个对映异构单体进行聚合时，由于体系中存在着某种不对称的诱导因素，其中之一比...     

手征性杂氮钛三环化合物的合成

杂氮钛三环(titatrane)(Ⅰ)是一类具有五配体特殊结构的杂环化合物,由于对其合成工作研究的不多,所以这类化合物的一些性质还鲜为人知。我们对杂氮钛三环的合成方法做了改进,将手性中心引入到这类化合物中,合成了下列结构图中(Ⅱ)所示的具有手性的杂氮钛三环。     

Direct Enantioselective Three‐Component Synthesis of Optically Active Propargylamines in Water

An enantioselective three‐component reaction of aldehydes, amines, and alkynes in water by using a bis(imidazoline)–Cu^I catalysts having a hydrophobic substituent and sodium dodecyl sulfate as a surfactant was developed. The reaction was applied to a broad range of aldehydes and alkynes to give optically active propargylamines with excellent yields (up to 99 %) and enantiomeric excesses (up to 99 % ee).     

光学活性C3合成子的不对称合成及应用

叙述了光学活性甘油醇及其衍生物等手性Ｃ３合成的合成方法,以及这些手性化合物在不对称有机合成中的应用,参考文献２４篇。     

光学活性3-(1'-羟基乙基)-4- 乙酰氧基-β-内酰胺的立体选择 性合成

(1'R,3R,4R)-N-取代-3-(1'-羟基乙基)-4-乙酰氧基-β-内酰胺(3)是合成青霉烯和碳青霉烯类β-内酰胺抗生素的关键中间体。以廉价的L-抗坏血酸为原料,制得S-缩异丙氧叉甘油醛(5),与胺反应定量转变成相应的手性亚胺(6a～6d),6与双烯酮[2+2]环加成反应,高立体选择性地合成3(S)-乙酰基-β-内酰胺(8a～8d),其非对映体过量由类似反庆的80%提高到接近100%。8a经四步反应得到目标化合物3a。     

Synthesis of Conjugated Optically Active Polymetallocenes

The development of methodology for synthesizing new materials in which metal atoms are linked by hydrocarbons whose electronic conjugation is unbroken is described. The fundamental idea is to twist the hydrocarbons into helices. By attaching bulky groups to their precursors, the helices can be made to twist mainly in one direction. The molecules synthesized are helicenes capped by five-membered rings to which metals are attached. If the size of the helix is chosen appropriately, a polymeric structure forms in which hydrocarbon rings and metal atoms alternate. An oligomer with Structure 22 is the first such material prepared. It and related structures might be precursors of molecular solenoids, examples of which are not yet known.     

Synthesis of Optically Active α-Hydroxyalkylphosphonates

Russian Journal of General Chemistry -     

First Isolation and Stereochemistry of Optically Active Telluroxides

Optically active telluroxides 1 and 2 were isolated for the first time by means of medium-pressure liquid chromatography using an optically active column. Absolute configuration of the telluroxides (+)-1 and (+)-2 was determined to be R based on their specific rotations and circular dichroism spectra. The configurational lability and mechanism for racemization via an achiral hydrate were clarified by kinetic study and isotope tracer experiment.     

Stereocontrolled Synthesis of Optically Active beta-D-glucopyranosides of 3-Hydroxy-7,8-didehydro-beta-ionol

A stereocontrolled synthesis of optically active beta-D-glucopyranosides 1-4 of 3-hydroxy-7,8-didehydro-beta-ionol utilizing an asymmetric transfer hydrogenation to alpha,beta-acetylenic ketones catalyzed by chiral ruthenium complexes as the key step is described.     

First Optically Active Heptalenes and their Absolute Configuration

It is shown that dimethyl 7-isopropyl-5, 10-dimethylheptalene-1, 2-dicarboxylate ( 1 ) and dimethyl 5, 6, 8, 10-tetramethylheptalene-1, 2-dicarboxylate ( 2 ) can be resolved via the corresponding mono-acids and with the aid of optically active primary or secondary amines such as 1-phenylethylamine or ephedrine into the (?)-(P)- and (+)-(M)-enantiomeres, respectively. Characteristic for the (P)-chirality of the heptalene π-skeleton with C₂ or pseudo-C₂ symmetry are two (?)-CE's at the long wavelength region (450–300 nm) followed by at least one intense (+)-CE at wavelengths about or below 300 nm. The absolute configuration of the heptalenes was correlated with the well-established absolute configuration of (+)-(R)- and (?)-(S)-1-phenylethanol.     

Synthesis of Optically Active beta-Amino Acid N-Carboxyanhydrides

Methodology has been developed for the general synthesis of optically active beta-amino acid N-carboxyanhydrides (beta-NCAs) through cyclization of N(beta)-Boc or N(beta)-Cbz beta-amino acids using phosphorus tribromide. The formation of beta-NCAs was confirmed by spectroscopy as well as an X-ray structural determination of beta-homoalanine-N-carboxyanhydride. The beta-NCA molecules could be polymerized in good yield to give optically active poly(beta-peptides) that adopt stable chiral conformations in solution. For example, helical oligo(L-beta-homophenylalanine) was synthesized by polymerization of L-beta-homophenylalanine-N-carboxyanhydride.     

Synthesis of Optically Active Hydroxyesters Using Biocatalysts

Optically active hydroxyesters were prepared using the fungusAspergillus nigerand the yeastSacharomyces cerevisiae.Substrate is converted highly specifically into optically active isomers with 95% purity. The R-hydroxyester was isolated by asymmetric reduction. (R,R)-Tartaric acid of 60% optical purity was used as an inductor     

The First Example of Optically Active Chlorophosphine: T-Butylphenylphosphinochlorioite

Abstract

In general, alkylthiophosphonium salts can react with nucleophiles both in the sense of the Arbusov rearrangement (a) and the exchange of alkylthio groups at the P atom (b). We have recently demonstrated¹ that in the case of highly “thiophilic” nucleophiles such as mercaptide anions or tris(N, N-dimethylamine)phosphine the reactive centre is the sulphur atom (c).     

Synthesis of Optically Active P‐Chiral and Optically Inactive Oligophosphines

A series of optically active P‐chiral oligophosphines (S,R,R,S)‐ 2 , (S,R,S,S,R,S)‐ 3 , (S,R,S,R,R,S,R,S)‐ 4 , and (S,R,S,R,S,R,R,S,R,S,R,S)‐ 5 with four, six, eight, and 12 chiral phosphorus atoms, respectively, were successfully synthesized by a step‐by‐step oxidative‐coupling reaction from (S,S)‐ 1 . The corresponding optically inactive oligophosphines 1′ – 5′ were also prepared. Their properties were characterized by DSC, XRD, and optical‐rotation analyses. While optically active bisphosphine (S,S)‐ 1 and tetraphosphine (S,R,R,S)‐ 2 behaved as small molecules, octaphosphine (S,R,S,R,R,S,R,S)‐ 4 and dodecaphosphine (S,R,S,R,S,R,R,S,R,S,R,S)‐ 5 exhibited the features of a polymer. Furthermore, DSC and XRD analyses showed that hexaphosphine (S,R,S,S,R,S)‐ 3 is an intermediate between a small molecule and a polymer. Comparison of optically active oligophosphines 1 – 5 with the corresponding optically inactive oligophosphines 1′ – 5′ revealed that the optically active phosphines have higher crystallinity than the optically inactive counterparts. It is considered that the properties of oligophosphines depend on the enantiomeric purity as well as the oligomer chain length.     

Synthesis of Optically Active Cyanohydrins Using Almond Meal

Asymmetric hydrocyanation of aldehydes was accomplished using almond meal, containing the enzyme oxynitrilase. Optically active cyanohydrins with high levels of enantiomeric purity were obtained following a simple procedure.     

Synthesis and Polymerization of Optically Active Mono-I-Menthyl Itaconate

Optically active mono-l-menthyl itaconate (MMI) was prepared from ita-conic acid and l-menthol. MMI was polymerized in bulk at 80°C to give a chiral homopolymer having -49.5° specific rotation. MMI (M₁ was copolymerized with styrene (ST, M₂), methyl methacrylate (MMA, M₂), and N-cyclohexylmaleimide (CHMI, M₂) by using 2,2′-azobisisobutyronitrile (AIBN) as the radical initiator and benzene as the polymerization solvent at 50°C. The monomer reactivity ratios (r₁, r₂) and Alfrey-Price Q, e values were determined to be r₁ = 0.28, r₂ = 0.32, Q₁ = 0.90, and e₁ = 0.75 in MMI-ST; r₁ = 0.09 and r₂ = 0.51 in MMI-MMA; and r₁ = 0.78 and r₂ = 0.39 in MMI-CHMI. The chiroptical properties of the polymers were investigated.     

手性环胍衍生物的合成

以L-天冬酰胺为原料经十步反应合成了光学纯的手性双环胍, 总收率为2.2%. 这一合成方法的优点是避免使用剧毒的硫光气和气味难闻的有机硫化物