包结聚合

本文主要叙述以脱胆酸(DCA)为包结体的包结聚合的研究历史。各种烯类单体、双烯、环状双烯、双炔、氯代丙烯腈等聚合单体在DCA管道中的包结聚合行为及不对称包结聚合。     

Polymerization and characterization of self‐assembled β‐cyclodextrin‐threaded chiral monomers

A helical inclusion complex polymer was fabricated through the polymerization of β‐cyclodextrin‐threaded chiral monomers. The photo induced polymerization of inclusion complex clusters caused shrinkage of the polymer and decreased the pitches, leading to the disappearance of spring‐like construction under TEM. From the results of circular dichroism of the inclusion complex polymer, the helical construction was confirmed, and an entanglement of the polymer chains is proposed. After removal of the β‐cyclodextrins from the pendant groups of the inclusion complex polymer, the helical structure was found to be maintained. The highly ordered molecular arrangement of β‐cyclodextrins removed from the inclusion complex polymer was confirmed using POM. Here we demonstrate the fabrication of helical polymer fibers composed of entangled polymers through self‐assembled β‐cyclodextrin‐threaded chiral monomers. The helical polymer construction was maintained by the entwisted polymer chains even after the removal of β‐cyclodextrins from the pendant groups of the inclusion complex polymer. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2975–2981, 2010     

Synthesis of chiral helical poly[p-(oligopinanylsiloxanyl)phenylacetylene]s and enantioselective permeability of their membranes

To develop better polymeric materials for optical-resolution membranes, we synthesized nine chiral phenylacetylenes containing pinanyl groups. We used them to investigate the effects of chemical structures, including the number and position of the chiral groups in the monomers, on the induction of chirality in the main chain during polymerization and on the degree of enantioselectivity in the permeation of the polymeric membranes. The monomers included six new chiral p-(oligomethylpinanylsiloxanyl)phenylacetylenes. The homopolymerizations of these nine monomers with a Rh complex produced high-molecular-weight polymers (molecular weight = 10⁵–10⁶). Of the five polymers with a chiral pinanyl group at the 1-position of each oligosiloxanyl group, all except for two polymers showed high molar ellipticity in the main-chain region in the circular dichroism spectra. This finding indicated that these polymers had a chiral helical main chain. The membranes fabricated from all the polymers synthesized in this study were high-quality, except for two polymers. All these membranes showed enantioselective permeabilities for two amino acids and an alcohol. The membranes from the polymers with a chiral helical backbone, a high content of pinanyl groups, no oligodimethylsiloxane moieties, or a combination of these showed good enantioselectivities (= 1.7–640) in permeation. We propose that the sense of the main-chain helicity determined the selectivity. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4502–4517, 2004     

手性氨基酸及其衍生物配体在酮不对称氢转移反应中的应用进展

前手性酮的不对称氢转移反应(ATH)是获得手性醇的重要方法.近年来氨基酸及其衍生物在金属Ru,Rh,Ir催化酮的ATH中的应用引起人们关注.就氨基酸、氨基酸酰胺、氨基酸硫代酰胺、氨基酸羟胺酸、氨基酸酰肼、氨基醇及氨基酸羟基酰胺等为配体的金属络合物在ATH中的催化性能进行了综述.     

Developments of chiral metallocenes as polymerization catalysts

This review article describes developments in chiral metallocenes as polymerization catalysts focusing on C2 symmetric ansa-zirconocene complexes. Selective synthesis of rac-isomers of ansa-zirconocenes are surveyed. Isospecific polymerizations of propylene catalyzed by chiral zirconocenes are summarized. Advanced series of polymerizations by chiral metallocenes such as asymmetric polymerization and polymerization of polar monomers are also introduced.     

Long‐range effects of chirality in aromatic poly(isocyanide)s

The preparation of optically active atropoisomeric polymers which present chiral backbones, thanks to induction during their synthesis from stereogenic centers, located far away from the skeleton is possible, thanks principally to semirigid conformations of the promesogenic spacers between them. The result is that chiral “information” can be passed as far as 21 Å from the asymmetric center to the carbon atom that forms the polymeric chain in poly(isocyanide)s. The sense of chiral induction in these conformationally rigid polymers parallels the helical sense of the cholesteric phases, as well as to the helical senses of chiral smectic C phases, induced by the monomers in nematic and smectic C phases, respectively. All these phenomena obey the odd–even rules proposed for chiral sense changes in these liquid crystalline phases. Noncovalent interactions play an important part in the induction process, in which steric arguments can be used to justify the inductions observed. The methodology can be used to prepare macromolecules, which display switching behavior upon thermal or electrochemical stimulus. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3161–3174, 2006     

Synthesis and modeling of new phosphorus‐containing acrylates

New methacrylate monomers containing phosphonic acid or both phosphonic and carboxylic acids were synthesized through the reaction of t‐butyl α‐bromomethyl acrylate with triethyl phosphite followed by the selective hydrolysis of the phosphonate or t‐butyl ester groups with trimethylsilyl bromide and trifluoroacetic acid. The copolymerization of these monomers with 2‐hydroxyethylmethacrylate was investigated with photodifferential scanning calorimetry at 40 °C with 2,2′‐dimethoxy‐2‐phenyl acetophenone as a photoinitiator. Quantum mechanical tools were also used to understand the mechanistic behavior of the polymerization reactions of these synthesized monomers. The propagation and chain‐transfer reactions were considered and rationalized. A strong effect of the monomer structure on the rate of polymerization was observed. The polymerization reactivities of the monomers increased with decreasing steric hindrance and/or increasing hydrogen‐bonding capacity because of the hydrolysis of the phosphonate and the t‐butyl ester groups. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2574–2583, 2005     

Synthesis of diisocyanides with phenolic groups and their polymerization to helically chiral poly(quinoxaline‐2,3‐diyl)s

The development of synthetic routes which lead to five new diisocyanide monomers with one or two phenolic groups is described. Their polymerization behavior is studied with Pd‐ and Ni‐based initiators, as well as under microwave irradiation. The polymerizability is mainly dominated by steric effects as is concluded from experiments using different protecting groups. Chiroptical properties of these new polymers are studied by CD‐spectroscopy. After deprotection, helically chiral poly(quinoxalin‐2,3‐diyl)s are obtained which display a Brønsted function attached to a stereolabile biaryl axis whose configuration should be influenced by the chiral polymer backbone. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1320–1329     

Helicity Induction and Its Static Memory of Poly(biphenylylacetylene)s Bearing Pyridine N‐Oxide Groups and Their Use as Asymmetric Organocatalysts

Novel poly(biphenylylacetylene) derivatives carrying different types of pyridine N‐oxide units with a bulky or less‐bulky substituent at a different position as the functional pendant groups (poly‐ 2a and poly‐ 2b ) were synthesized by the rhodium‐catalyzed polymerization of the corresponding monomers. The influence of the steric environment around the catalytically active pyridine N‐oxide sites on the helicity induction and its static memory as well as the asymmetric catalytic activities of the resulting helical polymers with a macromolecular helicity memory was investigated. The polyacetylenes formed an excess one‐handed helical conformation upon noncovalent interactions with optically active alcohols and the induced macromolecular helicities of the polyacetylenes were efficiently memorized after the removal of the chiral inducers. Poly‐ 2b with the macromolecular helicity memory showed an enantioselectivity for the catalytic asymmetric allylation of benzaldehydes, producing optically active allyl alcohols, although their enantioselectivities were low. On the other hand, poly‐ 2a exhibited a negligible catalytic activity probably due to the bulky substituent at the o‐position of the pyridine N‐oxide residues, while poly‐ 2a underwent a unique helix‐inversion with the increasing concentration of chiral alcohols and the opposite helicity of poly‐ 2a was further successfully memorized. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 2481–2490     

The Challenge of Linear (E)‐Enones in the Rh‐Catalyzed,Asymmetric 1,4‐Addition Reaction of Phenylboronic Acid: A DFT Computational Analysis

Why are linear (E)‐enones such challenging substrates in the Rh‐catalyzed asymmetric arylation with boronic acids, which is one of the most important asymmetric catalysis methods? DFT computations show that these substrates adopt a specific conformation in which the largest substituent is antiperiplanar to Rh^I π‐complexed with the C?C bond within the enantioselectivity‐determining carborhodation transition state. Additionally, for such structures, there is a strong, but not exclusive, preference for s‐cis enone conformation. This folding minimizes steric interactions between the substrate and the ligand, and hence reduces the enantioselectivity. This idea is further confirmed by investigating three computation‐only substrate “probes”, one of which is capable of double asymmetric induction, and a recent computationally designed 1,5‐diene ligand. On average, excellent agreement between predicted and experimental enantioselectivity was attained by a three‐pronged approach: 1) thorough conformational search within ligand and substrate subunits to locate the most preferred carborhodation transition state; 2) including dispersion interaction and long‐range corrections by SMD/ωB97xD/DGDZVP level of theory; and 3) full substrate and ligand modeling. Based on the results, a theory‐enhanced enantioselectivity model that is applicable to both chiral diene and diphosphane ligands is proposed.     

有机磷试剂在不对称反应中的应用

由于其结构多样性,有机磷化合物作为配体、催化剂、辅助剂、添加剂、底物以及试剂等在不对称反应中均获得了成功的应用,从而使有机磷试剂在不对称反应研究领域占有举足轻重的地位.本文全面介绍了本课题组近几年来围绕有机磷试剂在不对称反应中的应用,在醛的不对称硅氰化反应、内消旋环氧烷不对称开环反应、潜手性酮的不对称硼烷还原、不对称Friedel-Crafts烷基化、对映选择Mitsunobu、不对称aza-Morita-Baylis-Hillman、不对称aza-Henry以及硝基烯的不对称Michael加成反应等方面所取得的一些研究结果.     

Poly(pyrroles) containing chiral side chains: effect of substituents on the chiral recognition in the doped as well as in the undoped state of the polymer film

The chiral discrimination of different poly(pyrroles) grafted by chiral side chains was investigated both in the doped and undoped state of the polymer films. To verify the enantioselective properties in the doped state, cyclic voltammograms were recorded in acetonitrile in the presence of the enantiomers of camphorsulfonic acid and the potentiodynamic polymerization of the appropriate monomers was performed using the same chiral electrolytes. The enantiomericrecognition in the undoped state was investigated by the application of these modified electrode surfaces in the enantioselective electroreduction of the prochiral ketones 4-methyl benzophenone and 2,5-dimethyl benzophenone. One polymer exhibits a recognition ability in the doped state; the investigation for the undoped state is in progress. A second polymer does not show enantioselective properties either in the doped nor in the undoped state. Electronic Publication     

Chiral Ferrocenyl Amino Alcohols：Preparation and Application as Catalysts in the Enantioselective Reduction of Ketones Using NaBH4／I2

Five novel chiral ferrocenyl amino alcohols were prepared from natural amino acids and used as catalysts in the asymmetric reduction of prochiral ketones with NaBH4/I2 combination.The incorporation of the ferrocenyl moiety into the molecule of the chiral amino alcohols greatly improved their enantioselectivity in the catalysis.The optically active secondary alcohols were obt5ained in moderate to good enantiomeric excesses and high chemical yields.     

Asymmetric reduction of representative ketones with a bis-chiral oxazaborolidine system

In recent years, many optically active β-amino alcohols, mostly derived from naturally occurring α-amino acids, have been incorporated into the asymmetric synthesis as chiral auxiliaries or ligands.1 An effective asymmetric catalysts, the oxazaborolidine-borane reagents, which were originally pioneered by Itsuno and Corey,2 were generally prepared from chiral β-amino alcohols by the reaction with boric acid or formed in situ in the presence of borane. These reagents provide excellent enanti…     

Optically active dimethylsiloxane copolymers with nucleophilic chiral sulfur groups pendant to the polysiloxane chain

Polydimethylsiloxanes with part of the siloxane units bearing an optically active sulfoxide group were synthesized. These copolymers had chiral sulfur centres connected to the siloxane chain by a dimethylene bridge. They were obtained mostly by the kinetically controlled anionic ring-opening polymerization of 1-(2-organothioethyl)1,3,3,5,5-pentamethylcyclotrisiloxanes, followed by stereoselective oxidation of prochiral groups to yield partially enantiomeric sulfoxide groups. Sulfoxides bearing cyclic monomers were also used. Polymers were characterized by spectroscopy and polarimetry. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 879–888, 1997     

Enantioselective hydride abstraction in organic substrates: a novel use for chiral carbenium ions

[reaction: see text] It is surprising that chiral cations have not been used to distinguish between prochiral hydrides when converse notions, such as asymmetric addition of a hyride to a prochiral functional group or use of a chiral anion to distinguish between a pair of prochiral protons, are methods employed everyday in enantioselective synthesis. To the best of our knowledge, this Letter describes the first example of an oxidative enantioselective hydride transfer process.     

Development of a new class of C1-symmetric bisphosphine ligands for rhodium-catalyzed asymmetric hydrogenation

A new class of C₁-symmetric bisphosphine ligands with three hindered quadrants have been obtained through facile synthesis from chiral BINOL derivatives. Their rhodium complexes have exhibited high enantioselectivities (up to 98% ee) in the asymmetric hydrogenation of various unsaturated prochiral olefins, providing an efficient catalytic system for the enantioselective synthesis of chiral amino acids and amines.     

Studies on the synthesis and properties of ferroelectric side chain liquid crystalline polyoxetanes

Two series of novel ferroelectric liquid crystalline (FLC) monomers were derived from 3-(hydroxymethyl)-3-methyloxetane, used as the backbone unit, and 2-(S)-[2-(S)-methylbutoxy]propionic acid, as a chiral moiety. The corresponding polyoxetanes were prepared by ring-opening polymerization using BF₃ · OEt₂ as an initiator. In addition to the structure identification, their liquid crystal phase behavior and electrical properties are also studied. Before their connection to the chiral molecular moiety, two series of carboxylic acids, 4-(6-[(3-methyloxetan-3-yl)methoxy]alkoxy)-benzoic acids and 4,4′-[6-(3-methyloxetan-3-yl)alkoxy]biphenylcarboxylic acids, show the phase sequence K Sc I and K Sc N I, respectively. After connection, the phase behavior of the corresponding chiral monomers is changed from K Sc I to K Sc* N* I as well as from K Sc N I to K Sc* Sa I. Only the phase sequence K Sc* Sa I is observed in both series of polyoxetanes. All of the synthesized monomers exhibited enantiotropic chiral smectic C(Sc*) phase. The monomers, with the biphenyl unit linked directly with a chiral center, possessed higher spontaneous polarization (P_s) values. Polyoxetanes possess a wide temperature range for the liquid crystal phase, about 120°C, and the Sc* phase range can be up to 95°C. However, the position of the biphenyl unit will not affect the spontaneous polarization of the synthesized side chain FLC polyoxetanes. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2843–2855, 1997     

Synthesis of polymer microspheres functionalized with chiral ligand by precipitation polymerization and their application to asymmetric transfer hydrogenation

Monodisperse, crosslinked poly(divinylbenzene) and poly(methacrylic acid‐co‐ethylene glycol dimethacrylate) microspheres with (1R,2R)‐N¹‐toluenesulfonyl‐1,2‐diphenylethylene‐1,2‐diamine ((R,R)‐TsDPEN) moiety were successfully prepared by precipitation polymerization. Introduction site of the (R,R)‐TsDPEN moiety into the polymer microspheres could be controlled by changing the order of addition of the corresponding monomers. The functionalized polymer microspheres were applied to asymmetric transfer hydrogenation of ketone and imine. Polymer microsphere‐supported chiral catalysts showed good reactivity and enantioselectivity in the catalytic asymmetric transfer hydrogenations. Chiral secondary alcohol was quantitatively obtained with 94% ee in the asymmetric transfer hydrogenation of acetophenone in water. We also found that introduction site of the chiral catalyst and hydrophobicity of the microspheres, as well as degree of the crosslinking, affected the yield and enantioselectivity of chiral product in this reaction. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3340–3349, 2010     

Search for highly resolved electron spin resonance spectra of the transient radical in radical polymerization

The detection of highly resolved spectra in electron spin resonance (ESR) measurements of radical polymerization is presented. Well‐resolved ESR spectra of the propagating radical were detected in the radical polymerization of several vinyl monomers with a specially designed cavity and cell. More highly resolved ESR spectra of the propagating radicals of vinyl and diene compounds were observed with aconventional spectrometer without the specially designed cavity and cell. On the basis of the ESR spectra, propagation rate constants and dynamic behavior of propagating radicals are discussed. Moreover, the application of time‐resolved ESR spectroscopy to research on the initiation process in radical polymerization is shown. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 269–285, 2002