First Example of Highly Stereoselective Synthesis of 1,2,3‐Trisubstituted Cyclopropanes via Chiral Selenonium Ylides

A new strategy for the highly stereoselective synthesis of three stereoisomers of chiral 1,2,3‐trisubstituted cyclopropanes in good yields with excellent diastereoselectivities and very high enantioselectivities (up to >99 % ee) was developed via selenonium ylides (see scheme). Possible pathways for the asymmetric cyclopropanations were also proposed.

     

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.     

Optically Active Particles of Chiral Polymers

Particles constructed by chiral polymers (defined as PCPs) have emerged as a rapidly expanding research field in recent years because of their potentially wide‐ranging applications in asymmetric catalysis, enantioselective crystallization, enantioselective release, amongst many others. The particles show considerable optical activity, due to the chirality of the corresponding polymers from which the particles are derived. This review article presents an overview on PCPs with emphasis on our group's recent achievements in the preparation of PCPs derived from optically active helical polymers and their applications. PCPs can be prepared via emulsion polymerization, precipitation polymerization, and suspension polymerization by starting from monomers. Emulsification of preformed chiral polymers and self‐assembly approaches also can lead to PCPs. Chiral polymer‐based core/shell particles, hollow particles, and magnetic particles are also covered because of their remarkable properties and significant potential applications.

     

新型多氢键双功能手性酰胺类化合物的高效合成

以BINOL-3,3′-二羧酸为原料,经外消旋化合物的拆分和缩合反应,合成了7个新型的联二萘骨架手性酰胺类化合物,收率51%~70%,其结构经¹H NMR, ¹³C NMR, FT-IR, HR-MS（ESI）和元素分析表征。     

An Efficient Method for Catalytic Asymmetric Reduction of Diketones and Application of Synthesis to Chiral 2,5- Diphenylpyrrolidine and 2,5-Diphenylthiolane

Asymmetric reduction of diketones with borane reagents generated in situ using cheap and available NaBH_4 andSnCl_2 in the presence of(S)-(-)-α,α-diphenyl-2-pyrrolidinemethanol was successfully achieved to yield the corre-sponding chiral diols with excellent stereoselectivity and enantioselectivity.And the chiral diol was transformedinto optically pure C_2-symmetricl chiral amine or thioether.     

Noncovalent Chiral Functionalization of Graphene with Optically Active Helical Polymers

Optically active helical substituted (co)polyacetylenes containing pendent pyrene groups are prepared and then noncovalently immobilized on graphene via π–π interactions. The resulting graphene composite is characterized by XRD, FTIR, Raman, circular dichroism, UV‐vis absorption, TEM, TGA, and fluorescent spectroscopy techniques. The helical polyacetylene endows graphene with the desired optical activity. Also interestingly, the dispersibility of the functionalized graphene in tetrahydrofuran is remarkably improved due to the presence of the helical polymer chains. The present methodology opens new opportunities and serves as a versatile platform toward preparing novel graphene‐based materials.

     

Synthesis of Novel Chiral Ionic Liquid and Its Application in Reduction of Prochiral Ketones to the Corresponding Chiral Alcohols Using NaBH4

A novel chiral ionic liquid (CIL) based on nicotinium salt has been synthesized and used as an efficient asymmetric chiral catalyst for reduction of acetophenone derivatives with NaBH₄ in methanol at room temperature. The optically active alcohols were obtained in low to moderate enantiomeric excess in a short reaction time.     

Single-Layered Chiral Nanosheets with Dual Chiral Void Spaces for Highly Efficient Enantiomer Absorption

Although considerable effort in recent years has been devoted to the development of two-dimensional nanostructures, single-layered chiral sheet structures with a lateral assembly of discrete clusters remain elusive. Here, we report single-layered chiral 2D sheet structures with dual chiral void spaces in which discrete clusters of planar aromatic segments are arranged with in-plane AB order in aqueous methanol solution. The chirality of the sheet is induced by the slipped-cofacial stacks of rectangular plate-like aromatic segments in the discrete clusters which are arranged laterally with up and down packing, resulting in dual chiral void spaces. The chiral nanosheets function as superfast enantiomer separation nanomaterials, which rapidly absorb a single enantiomer from a racemic mixture with greater than 99 % ee.     

Attempt to Resolute Chiral Clusters by Optically Active Hydrazide

Due to the framework chirality optically active clusters can provide the proof that a cluster as a whole, and not one of its fragments, acts as a catalyst, most of the work have been directed to the synthesis of tetrahedron-type chiral clusters1-3. However, there remains another major problem to obtain the pure enantiomers. Although Vahrenkamp had obtained some pioneering results in this area before 19901, only several racemic chiral clusters have been separated into pure enantiomers until now…     

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     

Optically Active T-Butylphenylphosphinothioic Acid: Synthesis,Selected Structural Studies and Applications as a Chiral Solvating Agent

Abstract

Synthesis, structural studies and the use of the (?)-(S)- and (+)-(R) enantiomers of t-butylphenylphosphinothioic acid as a chiral solvating agent for the determination of enantiomeric purity is discussed. Systems that are the most extensively studied are emphasized.     

Single‐Layered Chiral Nanosheets with Dual Chiral Void Spaces for Highly Efficient Enantiomer Absorption

Although considerable effort in recent years has been devoted to the development of two‐dimensional nanostructures, single‐layered chiral sheet structures with a lateral assembly of discrete clusters remain elusive. Here, we report single‐layered chiral 2D sheet structures with dual chiral void spaces in which discrete clusters of planar aromatic segments are arranged with in‐plane AB order in aqueous methanol solution. The chirality of the sheet is induced by the slipped‐cofacial stacks of rectangular plate‐like aromatic segments in the discrete clusters which are arranged laterally with up and down packing, resulting in dual chiral void spaces. The chiral nanosheets function as superfast enantiomer separation nanomaterials, which rapidly absorb a single enantiomer from a racemic mixture with greater than 99 % ee.     

Baker's Yeast Mediated Reduction of Optically Active Diketone

Baker's yeast (BY) mediated reduction of synthetic substrate is a useful method for preparing chiral intermediate in synthesis chemistry1,2, because it is readily available and inexpensive. The selectivity is generally predicted by Prelog rule3, that is, a hydride is transferred to the re face of the prochiral ketone.The baker's yeast mediated reduction of bicyclic diketones was previously reported by several groups4-6, but to our knowledge, no application of this reduction to sesquiter-pene-…     

Baker＇s Yeast Mediated Reduction of Optically Active Diketone

Baker‘s yeast mediated reduction of optically active diketone is described. The two keto groups are efficiently differentiated and the ee value of the recovered material is considerably raised. It affords highly optically active key intermediates efficiently for the synthesis of natural polyhydroxylated agarofuran products.     

Chiral Monolithic Absorbent Constructed by Optically Active Helical‐Substituted Polyacetylene and Graphene Oxide: Preparation and Chiral Absorption Capacity

Chiral monolithic absorbent is successfully constructed for the first time by using optically active helical‐substituted polyacetylene and graphene oxide (GO). The preparative strategy is facile and straightforward, in which chiral‐substituted acetylene monomer (Ma), cross‐linker (Mb), and alkynylated GO (Mc) undergo copolymerization to form the desired monolithic absorbent in quantitative yield. The resulting monoliths are characterized by circular dichroism, UV–vis absorption, scanning electron microscopy (SEM), FT‐IR, Raman, energy‐dispersive spectrometer (EDS), X‐ray diffraction (XRD), Brunauer–Emmett–Teller (BET), XPS, and thermogravimetric analysis (TGA) techniques. The polymer chains derived from Ma form chiral helical structures and thus provide optical activity to the monoliths, while GO sheets contribute to the formation of porous structures. The porous structure enables the monolithic absorbents to demonstrate a large swelling ratio in organic solvents, and more remarkably, the helical polymer chains provide optical activity and further enantio‐differentiating absorption ability. The present study establishes an efficient and versatile methodology for preparing novel functional materials, in particular monolithic chiral materials based on substituted polyacetylene and GO.

     

Synthesis of Optically Active 1,4-Dioxane Nucleotide Analogs

Optically active nucleotide analogs were prepared that were composed of a 1,4-dioxane ring as the sugar analog to which either uracil or adenine attached together with two carboxylic ester groups, to be used as vehicles for formation of oligomers. The chiral 1,4-dioxane moiety was constructed from dimethyl L-tartrate via the corresponding (2R,3R)-dimethyl 2-O-allyl-tartrate.     

Synthesis and Polymerization of Optically Active N‐Propargylphosphonamidates: A Novel Helical Polymer Carrying a P‐Chiral Center

Summary: A diastereomeric pair of novel N‐propargylphosphonamidates, HCCCH₂NHP(O)(CH₃)O‐L ‐menthyl was synthesized by the successive condensations of methylphosphonic dichloride with L ‐menthol and propargylamine. The (R)‐P‐isomer ( 1a ) was isolated, and the absolute configuration was determined by XRD. Polymerization of 1a , and a mixture of 1a and (S)‐P‐isomer ( 1b ) was carried out with a zwitterionic Rh complex as a catalyst. cis‐Stereoregular polymers with number‐average molecular weights of 5 600–9 800 were obtained in good yields. Poly( 1a ) and poly( 1a ₂₉‐co‐ 1b ₇₁) exhibited large specific rotations (+408 and −146°), and intense Cotton effects ([θ] = +2.25 and −0.9 × 10⁴ deg · cm² · dmol⁻¹) based on the conjugated polyacetylene backbone around 325 nm in CHCl₃, indicating that these polymers have helical structures, whose predominant helical senses are opposite.

Polymerization of N‐propargylphosphonamidate.     

Microspheres Consisting of Optically Active Helical Substituted Polyacetylenes: Preparation via Suspension Polymerization and Their Chiral Recognition/Release Properties

Cross‐linked microspheres consisting of optically active helical substituted polyacetylenes are reported. For preparing the microspheres, substituted polyacetylene copolymers with pendent polymerizable CC bonds are first prepared and then used as macromonomers to copolymerize with acrylates via suspension polymerization, providing cross‐linked microspheres. The helical polymer segments render the microspheres with optical activity, whereas the acrylate‐based polymers afford the swelling property. CD and UV‐vis spectra demonstrate the optical activity of the microspheres. The microspheres preferably adsorb (R)‐(+)‐1‐phenylethylamine, (R)‐(+)‐N‐benzyl‐1‐phenylethylamine, and Boc‐D ‐alanine, whereas released Boc‐L ‐alanine rather more rapidly than its enantiomer.     

旋光性聚酰胺的合成,表征及其手性识别能力

用天然酒石酸与不同芳香二胺成盐后,经高温缩聚反应,合成了五种新的旋光性聚酰胺,讨论了聚合条件对聚合物的[α]_D~(20)值的影响以及聚合物的旋光稳定性、热稳定性。~1H-NMR及园二色(CD)谱显示聚合物的分子链存在某种有序构象。手性拆分实验初步显示所合成的聚酰胺对苯丙氨酸有手性识别能力。